{ "name": "Gaugelog Calibration Interval Reference", "version": "1.0", "published": "2026-07-11", "license": { "name": "CC BY 4.0", "url": "https://creativecommons.org/licenses/by/4.0/" }, "attribution": "Gaugelog Calibration Interval Reference, v1.0 (July 2026), https://gaugelog.com/calibration/intervals. Licensed CC BY 4.0.", "disclaimer": "Calibration intervals are a risk-based decision for the instrument owner, not a fixed rule. Guidance documents such as ILAC-G24 and OIML D 10 describe how to set and adjust them from usage, criticality and calibration history. Every interval in this dataset is a typical starting recommendation, not a compliance requirement.", "homepage": "https://gaugelog.com/calibration/intervals", "counts": { "instrumentTypes": 68, "verifiedSources": 236 }, "types": [ { "id": "accelerometer", "name": "Accelerometer", "synonyms": [ "vibration transducer", "vibration sensor", "piezoelectric accelerometer", "IEPE accelerometer", "shock transducer" ], "category": "acoustic-vibration", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "intervalBasis": "No normative calendar interval exists; sensor manufacturers and calibration laboratories recommend 12 months as the standard interval for accelerometers in routine service, with shorter intervals for harsh environments or high-stakes test programs and up to 24 months for occasionally used sensors with documented stability. The choice follows the risk-based approach of ILAC-G24 / OIML D 10.", "intervalFactors": [ "Severe shock events, such as drops onto hard floors or overloads well beyond the measurement range, which warrant immediate recalibration", "Sustained high-temperature exposure, which ages the piezoelectric element and shifts sensitivity", "Harsh outdoor or high-vibration service (structural monitoring, engine testing) versus benign laboratory use", "Criticality of the test data, for example certification testing or NVH programs with contractual accuracy requirements", "Documented sensitivity drift between successive calibrations, which justifies extending or shortening the cycle", "Continuous monitoring deployments, which call for calibration before installation and verification after removal" ], "standards": [ { "designation": "ISO 16063-21:2003", "title": "Methods for the calibration of vibration and shock transducers - Part 21: Vibration calibration by comparison to a reference transducer", "relevance": "The back-to-back comparison method in this part is the most common secondary calibration method for accelerometers, covering 0.4 Hz to 10 kHz" }, { "designation": "ISO 16063-11", "title": "Methods for the calibration of vibration and shock transducers - Part 11: Primary vibration calibration by laser interferometry", "relevance": "Primary method used by national metrology institutes to calibrate the reference standard accelerometers that comparison calibrations rely on" }, { "designation": "ISO 16063-12:2002", "title": "Methods for the calibration of vibration and shock transducers - Part 12: Primary vibration calibration by the reciprocity method", "relevance": "Alternative primary calibration method within the ISO 16063 series" } ], "sources": [ { "citation": "How Often Should I Recalibrate My Accelerometer?, The Modal Shop (PCB Piezotronics)", "url": "https://www.modalshop.com/calibration/learn/accelerometer-calibration-basics/recalibration-intervals", "supports": "Interval claim: most manufacturers recommend annual accelerometer calibration, with usage and test requirements dictating shorter or longer intervals, extension to two years for occasionally used sensors with documented stability, and recalibration after drops or temperature overexposure" }, { "citation": "Accelerometer Calibration: Methods, Standards & Intervals, Micro Precision Calibration", "url": "https://microprecision.com/blog/accelerometer-calibration-guide/", "supports": "Interval guidance of roughly 6 to 24 months depending on application criticality and environmental exposure, with annual as the common standard and more frequent calibration for high-stakes applications; also the back-to-back comparison method" }, { "citation": "ISO 16063-21:2003, Methods for the calibration of vibration and shock transducers - Part 21: Vibration calibration by comparison to a reference transducer, ISO", "url": "https://www.iso.org/standard/27053.html", "supports": "The back-to-back comparison calibration method, its frequency range, and its use by metrology labs for recalibration" } ], "guideUrl": "https://gaugelog.com/calibration/accelerometer" }, { "id": "analytical-balance", "name": "Analytical Balance", "synonyms": [ "laboratory balance", "lab balance", "semi-micro balance", "microbalance", "precision balance" ], "category": "mass-volume", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Daily or before-use internal adjustment plus routine external weight checks between calibrations; USP <41>/<1251> require periodic risk-based assessment of sensitivity and repeatability (in practice often weekly sensitivity and monthly repeatability and eccentricity checks) rather than a mandated daily test.", "intervalBasis": "No standard mandates a fixed interval; USP General Chapter 41 requires the balance to be calibrated over the operating range and checked periodically at a risk-based frequency the laboratory defines. Annual external calibration by a certified provider is the typical laboratory practice reported by GMP calibration guidance, with roughly 6 month cycles common in regulated or high-precision environments.", "intervalFactors": [ "Regulatory context: USP/GMP quality control weighing demands documented risk-based check frequencies and typically annual or semi-annual external calibration", "Operation near the balance's minimum weight leaves little margin, so repeatability drift matters more and argues for tighter control", "Environment: drafts, vibration, operator traffic, and temperature or humidity swings at the bench accelerate performance drift", "Usage intensity: heavily used shared balances justify shorter external calibration cycles than lightly used dedicated units", "Relocation or maintenance: moving a balance changes local gravity and leveling, requiring recalibration regardless of the calendar", "As-found drift history from previous certificates supports extending or shortening the cycle per ILAC-G24 methodology" ], "standards": [ { "designation": "USP General Chapter <41>", "title": "Balances (United States Pharmacopeia)", "relevance": "Mandatory requirements for balances used for materials that must be accurately weighed: calibration over the operating range plus repeatability and accuracy criteria, with periodic risk-based performance checks" }, { "designation": "USP General Chapter <1251>", "title": "Weighing on an Analytical Balance (United States Pharmacopeia)", "relevance": "Informational good weighing practice chapter covering qualification, routine checks, and minimum weight" }, { "designation": "OIML R 76-1", "title": "Non-automatic weighing instruments - Part 1: Metrological and technical requirements - Tests", "relevance": "Accuracy classification and maximum permissible errors for non-automatic weighing instruments, the basis for legal metrology control of balances" }, { "designation": "ASTM E617", "title": "Standard Specification for Laboratory Weights and Precision Mass Standards", "relevance": "Specifies the weight classes (with OIML R 111) acceptable as reference weights for balance calibration" } ], "sources": [ { "citation": "GMP Insiders, \"Calibration Of Analytical Balances And Performance Checks\" (GMP Insiders)", "url": "https://gmpinsiders.com/calibration-analytical-balances-performance-checks/", "supports": "The 12 month typical interval (external calibration by certified companies is typically performed annually), daily internal calibration practice, use of OIML R 111 or ASTM E617 weights, and the procedure steps" }, { "citation": "Mettler-Toledo, \"USP Chapters 41 and 1251 on Balances\" (METTLER TOLEDO library)", "url": "https://www.mt.com/us/en/home/library/collections/laboratory-weighing/USP-chapters-41-1251-weighing.html", "supports": "USP <41> requirements: calibration over the operating range, repeatability and accuracy requirements, and periodic risk-based performance checks between calibrations" }, { "citation": "United States Pharmacopeia, \"FAQs: Balances and Weighing on an Analytical Balance\" (USP)", "url": "https://www.usp.org/frequently-asked-questions/balances-and-weighing-analytical-balance", "supports": "The usage-based framing: no daily repeatability test is mandated, check frequency is determined by the laboratory through risk analysis, and sensitivity and repeatability must be periodically assessed" }, { "citation": "OIML R 76-1:2006, Non-automatic weighing instruments - Part 1: Metrological and technical requirements - Tests (OIML)", "url": "https://www.oiml.org/en/files/pdf_r/r076-1-e06.pdf", "supports": "Existence and scope of the legal metrology recommendation covering accuracy classes and maximum permissible errors for balances" } ], "guideUrl": "https://gaugelog.com/calibration/analytical-balance" }, { "id": "anemometer", "name": "Anemometer", "synonyms": [ "wind speed sensor", "cup anemometer", "vane anemometer", "propeller anemometer", "air velocity meter" ], "category": "flow", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Field (tower) check at initial installation and roughly every 3 to 6 months for meteorological installations, per R.M. Young's recommended schedule; also after any suspected impact or icing damage.", "intervalBasis": "No standard sets a universal interval; ASTM D5096 and ISO 17713-1 define wind tunnel test methods only. Manufacturer guidance is the common anchor: R.M. Young's wind system calibration manual recommends laboratory checks every 24 months (12 months for research accuracy) and manufacturer wind tunnel calibration every 24 months for research-grade accuracy, with field checks every 3 to 12 months in between.", "intervalFactors": [ "Bearing wear from continuous rotation in the field, which raises the starting threshold and changes low-speed response", "Exposure to icing, salt spray, dust, and insects that add drag or contaminate bearings", "Accuracy class required: R.M. Young roughly halves check intervals when research accuracy (plus or minus 0.3 m/s) rather than operational accuracy (plus or minus 0.5 m/s) is needed", "Wind energy resource assessment campaigns, which typically require wind tunnel calibration before deployment and verification afterward", "Physical damage to cups, propeller blades, or vanes from handling or storms" ], "standards": [ { "designation": "ASTM D5096", "title": "Standard Test Method for Determining the Performance of a Cup Anemometer or Propeller Anemometer", "relevance": "Defines wind tunnel determination of starting threshold, distance constant, transfer function, and off-axis response" }, { "designation": "ISO 17713-1:2007", "title": "Meteorology - Wind measurements - Part 1: Wind tunnel test methods for rotating anemometer performance", "relevance": "International wind tunnel test method for rotating (cup and propeller) anemometer performance, closely related to ASTM D5096" } ], "sources": [ { "citation": "R.M. Young Company, Wind System Calibration: Recommended Calibration Interval, Procedure, and Test Equipment, Manual 18860-90", "url": "https://www.youngusa.com/wp-content/uploads/2021/01/18860-90D.pdf", "supports": "Interval claim: recommended tower check every 6 months (3 for research accuracy), trailer check every 12 months (6), laboratory check every 24 months (12), and manufacturer wind tunnel check every 24 months for research accuracy; also the procedure steps and calibration equipment" }, { "citation": "ASTM D5096-02(2017), Standard Test Method for Determining the Performance of a Cup Anemometer or Propeller Anemometer, ASTM International", "url": "https://standards.globalspec.com/std/3863911/ASTM%20D5096-02(2017)", "supports": "Wind tunnel determination of starting threshold, distance constant, transfer function, and off-axis response" }, { "citation": "ISO 17713-1:2007, Meteorology - Wind measurements - Part 1: Wind tunnel test methods for rotating anemometer performance, ISO", "url": "https://www.iso.org/standard/31497.html", "supports": "International wind tunnel test method for rotating anemometer performance characteristics" } ], "guideUrl": "https://gaugelog.com/calibration/anemometer" }, { "id": "barometer", "name": "Barometer", "synonyms": [ "aneroid barometer", "digital barometer", "barometric pressure sensor", "atmospheric pressure gauge" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Between calibrations, WMO field practice is a one-point comparison against a travelling or reference standard at ambient pressure during station inspections.", "intervalBasis": "No normative interval exists; 12 months is the interval most manufacturers recommend for digital barometers ('Most manufacturers recommend a standard calibration interval of twelve months', Techmaster). WMO practice adds periodic one-point comparisons against a travelling standard between full calibrations.", "intervalFactors": [ "Aneroid capsules drift mechanically with age and temperature cycling, so older aneroid instruments need more frequent comparison than stable digital quartz sensors", "Transport and physical shock (field relocation, shipping) can shift the zero and justify an immediate check", "Use in aviation altimetry, meteorological networks, or accredited labs (ambient condition records) raises criticality and shortens the interval", "A documented drift trend from repeated comparisons against a reference barometer supports extending toward 24 months", "Harsh environmental conditions or operation outside the calibrated temperature band shortens the defensible interval" ], "standards": [ { "designation": "WMO-No. 8", "title": "Guide to Instruments and Methods of Observation (CIMO Guide), Chapter 3, Measurement of atmospheric pressure", "relevance": "Authoritative meteorological guidance on barometer use, comparison with travelling and reference standards, calibration, and maintenance" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval from drift history and risk" } ], "sources": [ { "citation": "Digital Barometer Calibration: The Complete Metrology Guide, Techmaster Electronics", "url": "https://techmaster.us/digital-barometer-calibration-the-complete-metrology-guide/", "supports": "The 12-month typical interval ('Most manufacturers recommend a standard calibration interval of twelve months'), shortening for harsh conditions, the six-step as-found/as-left procedure, the 800 to 1100 hPa test range, and reference equipment (quartz standards, pneumatic calibrators, piston gauges)" }, { "citation": "WMO-No. 8, Guide to Meteorological Instruments and Methods of Observation, Chapter 3, Measurement of atmospheric pressure, World Meteorological Organization", "url": "https://www.starpath.com/cyc/WMO-Barometers.pdf", "supports": "Comparison and calibration practice for barometers, including one-point field comparisons with a travelling standard during inspections (usage-based checks)" }, { "citation": "General Accreditation Guidance: The in-situ calibration of barometers, NATA (National Association of Testing Authorities, Australia)", "url": "https://nata.com.au/files/2021/05/In-situ-Calibration-of-Barometers.pdf", "supports": "In-situ comparison calibration of barometers against a reference standard as an accepted accreditation practice" } ], "guideUrl": "https://gaugelog.com/calibration/barometer" }, { "id": "bore-gauge", "name": "Bore Gauge", "synonyms": [ "bore gage", "dial bore gauge", "cylinder gauge", "cylinder bore gauge", "internal bore gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Set to a calibrated setting ring or master gauge before each measurement session; recalibrate immediately after a drop, mechanism overload, or measuring head replacement", "intervalBasis": "JIS B 7515 defines cylinder gauge requirements but no recalibration interval. The 12-month starting point is common quality system practice per accredited calibration labs (Techmaster: most quality systems calibrate a bore gage every 12 months, sooner after repair, overload or heavy use), with the final interval set by the user per ILAC-G24 / OIML D 10 risk methods.", "intervalFactors": [ "Anvil and guide wear from sliding contact inside bores; thousands of sweeps cause microscopic wear that shifts readings", "Frequency of measuring-head and extension-rod changes, since accuracy is not guaranteed after a head swap until re-verified", "Calibration status of the setting rings or master gauges used for zeroing, which cap the achievable accuracy", "Usage intensity in production bore checks, for example engine cylinder measurement, versus occasional toolroom use", "Shock events such as dropping the gauge or forcing it into an undersize bore, which damage the transfer mechanism" ], "standards": [ { "designation": "JIS B 7515", "title": "Cylinder gauges", "relevance": "Japanese Industrial Standard covering dial-type cylinder (bore) gauges, defining their construction and accuracy requirements used as calibration acceptance criteria" }, { "designation": "JIS B 7503", "title": "Mechanical dial gauges", "relevance": "Governs the dial gauge mounted on the bore gauge as the reading element; the indicator is often verified separately to this standard during bore gauge calibration" } ], "sources": [ { "citation": "Techmaster Electronics, \"Bore Gage Calibration: Definition, Principle & Guide\" (ISO/IEC 17025 accredited lab service page)", "url": "https://techmaster.us/bore-gage-calibration-definition-principle-guide/", "supports": "The 12-month typical interval (most quality systems calibrate a bore gage every 12 months, sooner after repair, overload or heavy use), the comparator nature of the instrument, use of a certified setting ring gauge as zero reference, anvil wear as a calibration driver, and the as-found/as-left MPE acceptance approach" }, { "citation": "JIS B 7515:1982, Cylinder gauges, Japanese Standards Association", "url": "https://webstore.ansi.org/standards/jis/jis75151982", "supports": "Standard designation and title; the governing Japanese standard for dial-type cylinder (bore) gauges cited as acceptance basis" }, { "citation": "Mitutoyo, \"Check Points for Measuring Instruments\" (Catalog No. E12024)", "url": "https://www.mitutoyo.com/Images/E12024_Check_Points_for_Measuring_Instruments.pdf", "supports": "The usage-based practice of performing initial setting with a calibrated master gauge or setting ring before measurement, checking smooth anvil and thimble movement before use, and the caution that accuracy is no longer guaranteed after a measuring head replacement" } ], "guideUrl": "https://gaugelog.com/calibration/bore-gauge" }, { "id": "calibration-weights", "name": "Calibration Weights", "synonyms": [ "test weights", "calibration masses", "mass standards", "weight sets", "check weights", "reference weights" ], "category": "mass-volume", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Recalibrate immediately after suspected damage, visible corrosion or contamination, bare-hand contact on high-class weights, or a drop; many labs also run interim intercomparisons against a higher-class check standard between calibrations.", "intervalBasis": "No standard or regulation specifically mandates a recalibration interval for weights; Troemner, a leading weight manufacturer, states that annual recalibration is the industry norm for infrequent to moderate use and recommends every 6 months for weights used very frequently. Intervals for carefully stored, rarely used reference sets can be extended based on documented as-found history per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Accuracy class: E1 and E2 weights have very tight maximum permissible errors, so small mass changes from handling consume tolerance quickly", "Frequency of use: weights used several times a day warrant a 6 month cycle versus annual for occasional use, per manufacturer guidance", "Handling discipline: use of gloves, tweezers, and forks versus bare hands strongly affects mass stability between calibrations", "Storage environment: humidity, corrosive atmospheres, and dust exposure accelerate mass change, especially for lower-grade materials", "Role in the traceability chain: weights used to calibrate other weights or high-resolution balances carry more risk when out of tolerance", "As-found results relative to class MPE on previous certificates justify extending or shortening the cycle per ILAC-G24 methods" ], "standards": [ { "designation": "OIML R 111-1:2004", "title": "Weights of classes E1, E2, F1, F2, M1, M1-2, M2, M2-3 and M3 - Part 1: Metrological and technical requirements", "relevance": "Defines the accuracy classes, maximum permissible errors, material and surface requirements, and test procedures for weights from 1 mg to 5 000 kg" }, { "designation": "ASTM E617", "title": "Standard Specification for Laboratory Weights and Precision Mass Standards", "relevance": "US specification for laboratory weight classes (000 through 7) including tolerance, magnetic property, density, and surface requirements" }, { "designation": "NISTIR 6969", "title": "Selected Laboratory and Measurement Practices and Procedures to Support Basic Mass Calibrations (NIST)", "relevance": "NIST good measurement practices and standard operating procedures used by state and industrial labs for calibrating weights" } ], "sources": [ { "citation": "Troemner, \"OIML Weights Class E1, E2, F1, and F2\" reference center article (Troemner)", "url": "https://www.troemner.com/reference-center/weights-reference-center/oiml-weights-class-e1-to-f2", "supports": "The interval claim: recalibrate once a year for infrequent to moderate use and every 6 months for very frequent use, and the statement that no standard or regulation specifically mandates a recalibration interval, annual being industry practice; also the class hierarchy where higher classes calibrate the next lower class" }, { "citation": "OIML R 111-1:2004, Weights of classes E1, E2, F1, F2, M1, M1-2, M2, M2-3 and M3 - Part 1: Metrological and technical requirements (OIML)", "url": "https://www.oiml.org/en/files/pdf_r/r111-1-e04.pdf", "supports": "The accuracy classes, scope (1 mg to 5 000 kg), maximum permissible errors, and test requirements referenced in the standards list and acceptance criteria" }, { "citation": "ASTM E617-23, Standard Specification for Laboratory Weights and Precision Mass Standards (ASTM International)", "url": "https://store.astm.org/e0617-23.html", "supports": "The US weight classification (classes 000 through 7) and requirements for maximum permissible error, magnetic properties, density, and surface finish" }, { "citation": "NISTIR 6969, Selected Laboratory and Measurement Practices and Procedures to Support Basic Mass Calibrations, 2019 Edition (NIST)", "url": "https://nvlpubs.nist.gov/nistpubs/ir/2019/NIST.IR.6969-2019.pdf", "supports": "Procedure details: 24 hour thermal and environmental equilibration of weights near the balance before calibration, and the SOP-based comparison approach with buoyancy and sensitivity corrections" } ], "guideUrl": "https://gaugelog.com/calibration/calibration-weights" }, { "id": "caliper", "name": "Caliper", "synonyms": [ "vernier caliper", "digital caliper", "dial caliper", "slide caliper", "caliper gage" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Zero check at the closed jaw position before use; immediate recalibration after a drop, jaw damage, or inconsistent readings", "intervalBasis": "No standard mandates a fixed caliper interval; ISO 13385-1 defines design and maximum permissible errors only. The 12-month starting point is the interval most quality systems use per calibration lab guidance (Techmaster), and the final interval is a risk-based user decision per the ILAC-G24 / OIML D 10 methodology, tightened or extended from as-found history.", "intervalFactors": [ "Usage intensity: a caliper used every shift wears its jaws and slide far faster than a drawer-stored tool, pushing intervals toward 3 to 6 months", "Exposure to coolant, chips, dust, and abrasive workpiece surfaces on the shop floor", "Handling risk: calipers are handheld and frequently dropped; any drop or visible jaw damage should trigger immediate recalibration", "Criticality of the toleranced features measured; safety-critical or customer-mandated inspections justify shorter intervals", "As-found calibration history: tools repeatedly found well within tolerance can be extended toward 18 to 24 months with documented justification", "Number of operators sharing the tool, which raises misuse and wear risk" ], "standards": [ { "designation": "ISO 13385-1:2019", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Design and metrological characteristics of callipers", "relevance": "Primary international standard defining design requirements and maximum permissible errors (MPE) used as calibration acceptance criteria for vernier, dial, and digital calipers" }, { "designation": "ASME B89.1.14", "title": "Calipers", "relevance": "American National Standard for digital, dial, and vernier calipers; used as the basis for caliper calibration test point selection in US practice" }, { "designation": "JIS B 7507", "title": "Vernier, dial and digital callipers", "relevance": "Japanese Industrial Standard specifying design, metrological characteristics, and accuracy classes for calipers; widely referenced by Japanese instrument makers such as Mitutoyo" } ], "sources": [ { "citation": "Techmaster Electronics, \"Caliper Calibration\" (ISO/IEC 17025 accredited lab service page)", "url": "https://techmaster.us/caliper-calibration/", "supports": "The 12-month typical interval (most quality systems calibrate a caliper every 12 months, sooner after repair, overload, or heavy use), the references to ISO 13385-1 and ASME B89.1.14, certified gauge blocks as reference equipment, and the as-found/as-left MPE acceptance approach" }, { "citation": "ISO 13385-1:2019, Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Design and metrological characteristics of callipers, International Organization for Standardization", "url": "https://www.iso.org/standard/71149.html", "supports": "Standard designation and title; MPE-based design and metrological characteristics used as calibration acceptance criteria" }, { "citation": "Mitutoyo America, \"Caliper Calibration Procedure - How to Calibrate a Caliper\" (educational resource)", "url": "https://www.mitutoyo.com/educational-resource/caliper-calibration-how-to-calibrate-a-caliper/", "supports": "ASME B89.1.14 as the American National Standard governing calibration of digital, dial, and vernier calipers and the error-hunting purpose of the procedure" }, { "citation": "Houston Precision Instruments, \"How Often Should Calipers and Micrometers Be Calibrated?\"", "url": "https://houstonprecision.com/how-often-should-calipers-and-micrometers-be-calibrated/", "supports": "The interval range: 12 months as the common standard interval, 3 to 6 months for heavy use or harsh conditions, and 18 to 24 months for lightly used tools with a documented history of staying in tolerance" } ], "guideUrl": "https://gaugelog.com/calibration/caliper" }, { "id": "clamp-meter", "name": "Clamp Meter", "synonyms": [ "clamp-on ammeter", "current clamp", "tong tester", "amp clamp", "clamp multimeter" ], "category": "electrical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Calibrate before planned critical measurements and after any drop or visible jaw damage, in addition to the routine yearly cycle.", "intervalBasis": "No standard sets a normative interval; Fluke's clamp meter calibration guidance states that clamp meters typically require yearly calibration to stay within manufacturer specifications, with earlier calibration after a drop or before critical measurements. The interval is a risk-based user decision per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Mechanical wear and contamination of the jaw mating surfaces, which directly degrades current transformer accuracy", "Drops and impacts in field service, which can shift the magnetic circuit and call for immediate recalibration", "Criticality of measurements, for example verifying loads for safety or billing versus rough troubleshooting", "Proportion of DC (Hall effect) measurements, since Hall sensors need regular zeroing and drift more than current transformers", "As-found history at low, mid, and full-scale current points from previous certificates" ], "standards": [ { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and reviewing the recalibration interval, since no instrument-specific normative interval exists for clamp meters" }, { "designation": "EURAMET cg-15", "title": "Guidelines on the Calibration of Digital Multimeters", "relevance": "Applicable calibration guidance for the voltage, resistance, and direct current functions that clamp multimeters share with DMMs" } ], "sources": [ { "citation": "Fluke Calibration, How To Calibrate a Clamp Meter: A Step-By-Step Guide (fluke.com learn blog)", "url": "https://www.fluke.com/en-us/learn/blog/calibration/how-to-calibrate-a-clamp-meter-guide", "supports": "Interval claim: states clamp meters typically require yearly calibration, with earlier calibration after a drop or before critical measurements; also multiproduct calibrator plus 50-turn coil setup, 1000 A example, alignment, and as-found/as-left sequence" }, { "citation": "Fluke Calibration, 5500A/COIL 50-Turn Current Coil (product page and instruction sheet)", "url": "https://www.fluke.com/en-us/product/accessories/calibration-accessories/5500a-coil", "supports": "Current multiplication by 50 turns, support for current transformer (AC) and Hall effect (AC/DC) clamps, and the centering/alignment requirement for guaranteed accuracy" }, { "citation": "ILAC-G24 / OIML D 10, Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Risk-based interval determination methodology cited in intervalBasis" } ], "guideUrl": "https://gaugelog.com/calibration/clamp-meter" }, { "id": "coating-thickness-gauge", "name": "Coating Thickness Gauge", "synonyms": [ "coating thickness gage", "dry film thickness gauge", "DFT gauge", "paint thickness gauge", "mil gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Verify gauge accuracy against certified coated thickness standards or certified shims before each use (at minimum each work shift) and check zero, or a known shim value, on the uncoated substrate before measuring, per ASTM D7091 practice and manufacturer guidance.", "intervalBasis": "No standard mandates a fixed recalibration interval for these gauges. Manufacturer DeFelsko advises starting with a one year calibration interval from the date of calibration, purchase, or receipt, then adjusting from experience; ASTM D7091 separately requires frequent in-use accuracy verification against certified standards.", "intervalFactors": [ "Frequency of use: gauges measured daily on production or blast-cleaned steel wear probes faster than occasionally used units", "Probe wear from abrasive or rough-profile surfaces, which shifts readings especially at low thicknesses", "Level of care in handling and storage; field gauges carried on site drift faster than lab-kept units", "Criticality of the coating specification, for example contractual DFT acceptance under inspection regimes", "As-found history from shift verifications on certified shims: repeated adjustment needs justify a shorter interval" ], "standards": [ { "designation": "ISO 2178:2016", "title": "Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method", "relevance": "Governs magnetic-method coating thickness measurement on ferrous substrates, the primary use case for these gauges." }, { "designation": "ISO 2360:2017", "title": "Non-conductive coatings on non-magnetic electrically conductive base metals - Measurement of coating thickness - Amplitude-sensitive eddy-current method", "relevance": "Governs eddy-current coating thickness measurement on non-ferrous conductive substrates." }, { "designation": "ASTM D7091", "title": "Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals", "relevance": "Defines the three-step regime of calibration, verification, and adjustment of coating thickness gauges and the recommended verification frequency." }, { "designation": "ASTM E376", "title": "Standard Practice for Measuring Coating Thickness by Magnetic-Field or Eddy Current (Electromagnetic) Testing Methods", "relevance": "Related practice covering electromagnetic coating thickness measurement methods." } ], "sources": [ { "citation": "DeFelsko Corporation, \"Looking After Your Coating Thickness Gage\" (manufacturer resource)", "url": "https://www.defelsko.com/resources/looking-after-your-coating-thickness-gage", "supports": "Backs the interval claim: DeFelsko advises starting with a one year calibration interval and adjusting for usage frequency, application, and handling care; also backs verification against certified standards." }, { "citation": "ASTM D7091-22, Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals, ASTM International", "url": "https://store.astm.org/d7091-22.html", "supports": "Backs the calibration, verification, and adjustment regime, the per-use/per-shift verification trigger, and the use of certified standards and shims." }, { "citation": "ISO 2178:2016, Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method, ISO", "url": "https://standards.iteh.ai/catalog/standards/iso/eca08554-1165-44be-8b45-c352e1ca63ae/iso-2178-2016", "supports": "Backs the governing method standard for magnetic-induction coating thickness measurement on ferrous substrates." }, { "citation": "ILAC-G24 / OIML D 10, Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories, Edition 2022, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Backs the framing that the recalibration interval is a user-determined, risk-based decision reviewed against as-found data." } ], "guideUrl": "https://gaugelog.com/calibration/coating-thickness-gauge" }, { "id": "conductivity-meter", "name": "Conductivity Meter", "synonyms": [ "conductivity gage", "EC meter", "conductivity analyzer", "TDS meter", "conductivity/resistivity meter" ], "category": "chemical-analytical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Verify/redetermine the cell constant with a certified KCl standard regularly (daily for critical measurements), and recalibrate after cell cleaning, replacement, or any suspected fouling/polarization.", "intervalBasis": "ASTM D1125 specifies standard KCl reference solutions and cell-constant determination but does not fix a recalibration interval; frequency is a user decision. Labs commonly verify the cell constant against KCl standards frequently (daily to weekly for critical work) with full calibration typically every 6 to 12 months.", "intervalFactors": [ "Frequency of cell-constant verification already performed against KCl standards", "Cell fouling: scaling, oil, or biofilm changes the effective cell constant and shortens the interval", "Measurement range: high-purity water resistivity measurement is more sensitive and needs tighter control than bulk-water conductivity", "Temperature compensation accuracy and stability of the operating temperature", "Electrode/cell material wear and polarization at higher conductivities", "As-found drift of the measured cell constant over time" ], "standards": [ { "designation": "ASTM D1125", "title": "Standard Test Methods for Electrical Conductivity and Resistivity of Water", "relevance": "Defines conductivity/resistivity measurement of water, standard KCl reference solutions, and cell-constant determination." } ], "sources": [ { "citation": "ASTM D1125, Standard Test Methods for Electrical Conductivity and Resistivity of Water, ASTM International", "url": "https://store.astm.org/d1125-23.html", "supports": "Standard KCl reference solutions, their certified conductivity values, and cell-constant determination method." }, { "citation": "CalibrationOS, Conductivity Meter Calibration guide", "url": "https://calibrationos.com/guides/calibrate-conductivity-meter", "supports": "Cell-constant determination from a certified KCl standard per ASTM D1125, verification at a minimum of three standards spanning the range, and the 6 to 12 month interval with weekly verification for pharmaceutical water." }, { "citation": "Pharmaguideline, SOP for Calibration of Conductivity Meter", "url": "https://www.pharmaguideline.com/2011/10/sop-for-calibration-of-conductivity.html", "supports": "Routine KCl-standard verification procedure (daily calibration with KCl solution) and calibration frequency practice in regulated labs, supporting frequent verification between full calibrations." } ], "guideUrl": "https://gaugelog.com/calibration/conductivity-meter" }, { "id": "cmm", "name": "Coordinate Measuring Machine (CMM)", "synonyms": [ "coordinate measuring machine", "bridge CMM", "CNC CMM", "coordinate measurement machine", "3D measuring machine" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Interim checks with a calibrated artifact (machine checking gauge, ball bar, step gauge, or ring gauge) between annual verifications, typically weekly to monthly, and immediately after collisions, probe crashes, relocation, or unexpected measurement variation.", "intervalBasis": "ISO 10360-2 defines the reverification tests but does not fix their frequency. Most CMM manufacturers and calibration providers recommend a full calibration and verification at least once every 12 months as the starting point, shortened for multi-shift use, unstable environments, or tight-tolerance work.", "intervalFactors": [ "Machine utilization: continuous multi-shift operation versus occasional use in a metrology room", "Environmental stability, since shop-floor temperature swings and vibration degrade volumetric accuracy faster than a controlled lab", "Tolerance criticality of the parts measured (aerospace and medical features consume more of the error budget)", "Collision history, since probe crashes can shift machine geometry and probing performance immediately", "Machine age and wear of bearings, scales, and drive systems", "Results of interim artifact checks, which can justify extending or force shortening the full verification cycle" ], "standards": [ { "designation": "ISO 10360-2", "title": "Geometrical product specifications (GPS) - Acceptance and reverification tests for coordinate measuring machines (CMM) - Part 2: CMMs used for measuring linear dimensions", "relevance": "Defines the acceptance and periodic reverification tests, including the length measurement error E0 compared against the manufacturer's stated maximum permissible error E0,MPE; 2009 edition." } ], "sources": [ { "citation": "CMMXYZ, \"How to Determine Proper CMM Calibration Frequency\" (CMM sales and calibration provider guide)", "url": "https://www.cmmxyz.com/blog/when-does-your-cmm-need-calibration-a-complete-frequency-guide/", "supports": "Interval claim: most manufacturers and standards organizations recommend full CMM calibration at least once every twelve months as a starting point, with high utilization, tight tolerances, environmental instability, machine age, and warning signs shortening the interval, supplemented by interim verification." }, { "citation": "ISO 10360-2:2009, Geometrical product specifications (GPS) - Acceptance and reverification tests for coordinate measuring machines (CMM) - Part 2: CMMs used for measuring linear dimensions, International Organization for Standardization", "url": "https://www.iso.org/standard/40954.html", "supports": "Standard confirmation: specifies acceptance tests and periodic reverification tests for CMMs measuring linear dimensions, including the E0 length measurement error against E0,MPE." }, { "citation": "Flack, D., Measurement Good Practice Guide No. 42: CMM Verification, National Physical Laboratory (NPL), Issue 2", "url": "https://eprintspublications.npl.co.uk/2045/1/mgpg42.pdf", "supports": "Procedure grounding: NPL good practice for CMM verification testing and the use of calibrated artifacts for periodic and interim verification." }, { "citation": "Renishaw, \"MCG machine checking gauge\" product and knowledge base page", "url": "https://www.renishaw.com/cmmsupport/knowledgebase/en/mcg-machine-checking-gauge--22188", "supports": "Usage-based interim check claim: a 10 to 20 minute interim verification of volumetric accuracy to ISO 10360-2 that shows whether servicing or recalibration is needed between full calibrations." } ], "guideUrl": "https://gaugelog.com/calibration/cmm" }, { "id": "depth-gauge", "name": "Depth Gauge", "synonyms": [ "depth gage", "depth micrometer", "vernier depth gauge", "digital depth gauge", "dial depth gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Zero check on a surface plate or reference flat before use; immediate recalibration after a drop or when changing to an unverified measuring rod", "intervalBasis": "No instrument standard sets a normative interval; JIS B 7518 and JIS B 7544 define accuracy requirements only. The 12-month starting point mirrors common quality system practice for the caliper and micrometer instrument family as stated by calibration providers (Houston Precision Instruments), adjusted by the user per ILAC-G24 / OIML D 10 risk methods.", "intervalFactors": [ "Wear of the base reference face from sliding on rough castings or machined edges, which shifts the zero plane", "Use of interchangeable measuring rods on depth micrometers; each rod change risks seating error and each rod needs verification", "Usage intensity: daily production depth checks push intervals toward 3 to 6 months, occasional toolroom use supports longer intervals", "Criticality of depth tolerances such as counterbore and seal groove depths on safety-relevant parts", "Handling risk from drops onto the base or rods; recalibrate immediately after impact or if zero will not hold" ], "standards": [ { "designation": "JIS B 7518", "title": "Vernier, dial and digital depth gauges", "relevance": "Japanese Industrial Standard specifying maximum permissible errors for caliper-type depth gauges by measuring depth range, used as calibration acceptance criteria" }, { "designation": "JIS B 7544", "title": "Depth micrometers", "relevance": "Japanese Industrial Standard for micrometer-screw depth gauges (depth micrometers) up to 300 mm maximum measuring length, defining their accuracy requirements" } ], "sources": [ { "citation": "Houston Precision Instruments, \"How Often Should Calipers and Micrometers Be Calibrated?\"", "url": "https://houstonprecision.com/how-often-should-calipers-and-micrometers-be-calibrated/", "supports": "The 12-month common starting interval for the caliper and micrometer instrument family that depth gauges belong to, the 3 to 6 month shortening for heavy use, and the 18 to 24 month extension for lightly used tools with documented in-tolerance history" }, { "citation": "APE Software, \"Free Depth Micrometer Calibration Procedure\" (Calibration Control help library)", "url": "https://www.apesoftware.com/help/calibration-procedures/depth-micrometer", "supports": "The procedure outline: gauge block set and surface plate as standards, zero verification on the surface plate, test points at zero, midway, and full length including intermediate thimble positions, and graduation-based acceptance tolerances" }, { "citation": "JIS B 7518, Vernier, dial and digital depth gauges, Japanese Standards Association", "url": "https://webstore.ansi.org/standards/jis/jis75182018", "supports": "Standard designation and title, and the depth-range-dependent maximum permissible errors used as acceptance criteria for caliper-type depth gauges" }, { "citation": "JIS B 7544:1994, Depth micrometers, Japanese Standards Association", "url": "https://webstore.ansi.org/standards/jis/jis75441994", "supports": "Standard designation and title for micrometer-screw depth gauges (depth micrometers) up to 300 mm maximum measuring length" } ], "guideUrl": "https://gaugelog.com/calibration/depth-gauge" }, { "id": "dial-indicator", "name": "Dial Indicator", "synonyms": [ "dial gauge", "dial gage", "plunger indicator", "digital indicator", "drop indicator" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 1, "max": 24 }, "usageBasedInterval": "Function and zero check against a reference before critical use; immediate recalibration after a drop, overtravel shock, or repair", "intervalBasis": "ISO 463 and ASME B89.1.10M define metrological characteristics and test methods, not a mandatory interval. The 12-month starting point is common quality system practice per calibration labs (Techmaster), while repair specialists note the honest range is usage driven: a gage used monthly can be calibrated yearly, and one used hourly may warrant monthly checks (Long Island Indicator).", "intervalFactors": [ "Hours of use per day: an indicator on a production checking fixture accumulates travel cycles far faster than a toolroom instrument", "Shock and overtravel events, such as slamming the plunger or dropping the indicator, which damage the gear train", "Contact point wear and loosening, which directly offsets readings", "Dust, coolant mist, and chips entering the stem or rack in shop environments", "Criticality of the checks performed, for example runout limits on safety-related rotating parts", "As-found repeatability and hysteresis trends from previous calibrations" ], "standards": [ { "designation": "ISO 463:2006", "title": "Geometrical Product Specifications (GPS) - Dimensional measuring equipment - Design and metrological characteristics of mechanical dial gauges", "relevance": "Primary international standard for mechanical dial gauges defining MPE and metrological characteristics verified at calibration" }, { "designation": "ASME B89.1.10M-2001", "title": "Dial Indicators (for Linear Measurements)", "relevance": "US standard providing essential requirements and calibration basis for dial indicators" }, { "designation": "JIS B 7503", "title": "Mechanical dial gauges", "relevance": "Japanese Industrial Standard specifying accuracy classes and test methods for dial gauges, cited on manufacturer inspection certificates" } ], "sources": [ { "citation": "Techmaster Electronics, \"Dial Indicator Calibration\" (ISO/IEC 17025 accredited lab service page)", "url": "https://techmaster.us/dial-indicator-calibration/", "supports": "The 12-month typical interval (most quality systems calibrate a dial indicator every 12 months, sooner after repair, overload or heavy use), ASME B89.1.10M as the primary US standard, test points at 25/50/75/100 percent with Grade 0 or AS-1 gauge blocks, hysteresis and repeatability checks, and the plus or minus one graduation acceptance practice" }, { "citation": "Long Island Indicator Service, \"Calibration Procedures\"", "url": "https://www.longislandindicator.com/calibration/", "supports": "The usage-based interval range (a gage used once a month can be calibrated once a year; a gage used hourly should have about a one-month calibration), the mechanical calibrator and gauge block methods, the accuracy rule of not more than one graduation over the first 2-1/3 revolutions, and repeatability within half a graduation" }, { "citation": "ISO 463:2006, Geometrical Product Specifications (GPS) - Dimensional measuring equipment - Design and metrological characteristics of mechanical dial gauges, International Organization for Standardization", "url": "https://www.iso.org/standard/42802.html", "supports": "Standard designation, title, and the MPE-based metrological characteristics verified during calibration" } ], "guideUrl": "https://gaugelog.com/calibration/dial-indicator" }, { "id": "dial-test-indicator", "name": "Dial Test Indicator", "synonyms": [ "test indicator", "lever indicator", "lever-type dial indicator", "finger indicator", "DTI" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 1, "max": 24 }, "usageBasedInterval": "Function check through the full stylus arc before use; immediate recalibration after a crash, drop, or stylus replacement", "intervalBasis": "No instrument standard sets a recalibration interval for lever-type test indicators: ISO 9493 defines their design and metrological characteristics, while JIS B 7533 and DIN 2270 give maximum permissible errors. Annual calibration is the common compliance practice, and indicator repair specialists advise scaling frequency with use, from yearly for a gage used monthly down to about monthly for a gage used hourly (Long Island Indicator), consistent with ILAC-G24 / OIML D 10.", "intervalFactors": [ "Usage intensity on machine setup and inspection work; daily spindle-alignment use argues for intervals well under 12 months", "Stylus wear and bent styli from crashes; a bent or replaced stylus changes effective length and requires recalibration", "Shock sensitivity of the jeweled lever movement, including drops from magnetic base setups", "Criticality of runout and alignment tolerances being verified, for example on machine tool spindles", "As-found repeatability history across calibrations, which supports extending or shortening the interval" ], "standards": [ { "designation": "ISO 9493:2010", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment: Dial test indicators (lever type) - Design and metrological characteristics", "relevance": "International standard for lever-type dial test indicators, defining the design and metrological characteristics verified at calibration" }, { "designation": "JIS B 7533", "title": "Dial test indicators (lever type)", "relevance": "Japanese Industrial Standard specifying accuracy across the indicating range, repeatability, and dial requirements for lever-type test indicators; corresponds to ISO 9493:2010" }, { "designation": "DIN 2270", "title": "Geometrical product specifications (GPS) - Dial test indicators (lever type) - Maximum permissible errors", "relevance": "German standard giving maximum permissible error values for lever-type dial test indicators complying with DIN EN ISO 9493, widely referenced as numeric acceptance criteria" } ], "sources": [ { "citation": "Long Island Indicator Service, \"Calibration Procedures\"", "url": "https://www.longislandindicator.com/calibration/", "supports": "The interval guidance applied to indicators including test indicators: usage-based scaling from yearly (monthly use) down to about monthly (hourly use), calibration with a dial indicator calibrator and test indicator attachment or with certified gauge blocks on a surface plate, and repeatability within half a graduation" }, { "citation": "Techmaster Electronics JSC, \"Dial - Digital - Dial Test Indicator Calibration\" (calibration service procedure page)", "url": "https://techmaster.com.vn/en/dial-digital-dial-test-indicator-calibration/", "supports": "The procedure for lever-type indicators: positioning the stylus close to parallel with the calibrator anvil surface to minimize cosine error, test points at about 25/50/75/100 percent of full scale, use of Grade 0, 1, or 2 gauge blocks and Mitutoyo UDT-type calibrators, and acceptance to customer or manufacturer tolerances" }, { "citation": "ISO 9493:2010, Geometrical product specifications (GPS) - Dimensional measuring equipment: Dial test indicators (lever type) - Design and metrological characteristics, International Organization for Standardization", "url": "https://www.iso.org/standard/44708.html", "supports": "Standard designation and title; the international standard covering design and metrological characteristics of lever-type dial test indicators" }, { "citation": "DIN 2270, Geometrical product specifications (GPS) - Dial test indicators (lever type) - Maximum permissible errors, DIN (German Institute for Standardization)", "url": "https://webstore.ansi.org/standards/din/din22702017", "supports": "Standard designation and title defining the MPE acceptance criteria for lever-type dial test indicators" }, { "citation": "JIS B 7533:2015, Dial test indicators (lever type), Japanese Standards Association", "url": "https://webstore.ansi.org/Standards/JIS/JIS75332015", "supports": "Standard designation and title; accuracy and repeatability requirements for lever-type test indicators used as calibration acceptance criteria" } ], "guideUrl": "https://gaugelog.com/calibration/dial-test-indicator" }, { "id": "differential-pressure-gauge", "name": "Differential Pressure Gauge", "synonyms": [ "differential pressure gage", "DP gauge", "Magnehelic gauge", "low differential pressure gauge" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Re-zero with both ports vented to atmosphere whenever the pointer is off zero (Dwyer recommends occasionally venting and re-zeroing in service), and recalibrate or replace after any overpressure event beyond the rated limit.", "intervalBasis": "No standard or manufacturer document fixes an interval for DP gauges; Dwyer's Magnehelic manual requires only re-zeroing and factory recalibration when needed. The 12-month starting point follows general gauge practice, for example Ashcroft's guidance that the typically suggested time to check gauge calibration is once every 12 months, adjusted by risk per ILAC-G24/OIML D 10.", "intervalFactors": [ "Regulated environments: cleanroom and pharma facilities typically hold DP gauges to fixed annual (or stricter) calibration schedules for compliance", "Zero drift observed between checks is the clearest signal to shorten the checking interval", "Diaphragm overpressure events beyond the rated limit can permanently damage the gauge and require replacement or factory recalibration", "Dirty or dusty vented ports contaminate the gauge interior and degrade accuracy faster", "Mounting position changes matter: standard Magnehelic gauges are calibrated diaphragm-vertical and must be re-zeroed (or factory-calibrated) for other orientations", "Criticality of the point, for example patient-area isolation room monitoring versus a simple filter-clog indicator" ], "standards": [ { "designation": "ASME B40.100-2022", "title": "Pressure Gauges and Gauge Attachments", "relevance": "US standard for dial-type pressure gauges including accuracy grades applied to differential and duplex gauge products" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting the calibration interval, since neither the gauge standards nor Dwyer specify one" } ], "sources": [ { "citation": "Dwyer Instruments, Bulletin A-27, Magnehelic Differential Pressure Gage installation and operating instructions", "url": "https://assets.dwyeromega.com/manuals-do/A_27_rev6.pdf", "supports": "Accuracy of plus/minus 2 percent of full scale, calibration in the vertical diaphragm position, external zero adjustment with both ports vented, no periodic servicing required, and that user recalibration is not recommended (factory recalibration)" }, { "citation": "Ashcroft blog, \"How Often Should I Check the Calibration of My Pressure Gauge?\"", "url": "https://blog.ashcroft.com/pressure-gauge-calibration-interval", "supports": "The 12-month interval baseline: typically suggested calibration check for pressure gauges is once every 12 months, with the user responsible for adjusting it to conditions" }, { "citation": "ILAC-G24 / OIML D 10:2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "The risk-based interval-setting methodology used because no DP-gauge-specific normative interval exists" } ], "guideUrl": "https://gaugelog.com/calibration/differential-pressure-gauge" }, { "id": "digital-multimeter", "name": "Digital Multimeter", "synonyms": [ "DMM", "multimeter", "digital volt-ohm meter", "handheld multimeter", "bench multimeter" ], "category": "electrical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Recalibrate after overload events, input protection damage, or mechanical shock, and calibrate before and after major critical measurement projects.", "intervalBasis": "Manufacturer accuracy specifications are the anchor: Fluke specifies handheld DMM accuracy (e.g. the 87V) for one year after calibration, and Fluke's calibration guidance states the most common DMM calibration interval is yearly. It is a risk-based user decision per ILAC-G24 / OIML D 10, shortened for critical use and sometimes extended for stable, lightly used meters.", "intervalFactors": [ "The manufacturer accuracy specification period, typically one year, which the interval should not silently exceed", "Frequency and criticality of measurements: frequent critical work justifies quarterly or semiannual calibration, infrequent use can support longer cycles", "Electrical overload events, blown input fuses, or drops, which call for immediate recalibration regardless of schedule", "Environment: temperature and humidity outside roughly 18 to 28 C and 90 percent RH limits invalidate the accuracy spec conditions", "As-found history: consistently in-tolerance results across all functions support interval extension via ILAC-G24 methods" ], "standards": [ { "designation": "EURAMET cg-15", "title": "Guidelines on the Calibration of Digital Multimeters", "relevance": "European calibration guide defining calibration of DMM functions (DC/AC voltage, DC/AC current, resistance) and uncertainty evaluation for calibration laboratories" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and reviewing the DMM recalibration interval from usage and as-found data" } ], "sources": [ { "citation": "Fluke Calibration, Multimeter Calibrator Selection / How to Calibrate a Digital Multimeter (fluke.com learn blog)", "url": "https://www.fluke.com/en-us/learn/blog/calibration/how-calibrate-digital-multimeter", "supports": "Interval claim: states the most common DMM calibration interval is yearly; also 5522A calibrator use, 4:1 precision ratio, function/range coverage, and the verify-adjust-verify sequence" }, { "citation": "Fluke 87V Industrial Multimeter product specifications, Fluke Corporation", "url": "https://www.fluke.com/en-us/product/electrical-testing/digital-multimeters/fluke-87v", "supports": "Interval anchor: accuracy is specified for a period of one year after calibration at 18 to 28 C, which underpins the 12-month starting interval" }, { "citation": "EURAMET cg-15, Guidelines on the Calibration of Digital Multimeters, EURAMET (Calibration Guide, Version 3.0, 2015)", "supports": "Calibration procedure coverage of DC/AC voltage, DC/AC current, and resistance functions and lab practice for DMM calibration" }, { "citation": "ILAC-G24 / OIML D 10, Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Risk-based interval adjustment methodology cited in intervalBasis and intervalFactors" } ], "guideUrl": "https://gaugelog.com/calibration/digital-multimeter" }, { "id": "digital-thermometer", "name": "Digital Thermometer", "synonyms": [ "digital contact thermometer", "electronic thermometer", "digital probe thermometer", "handheld thermometer", "DCT" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "A single-point ice point (0 C) or known-reference check between calibrations is a common quick verification, especially after suspected probe damage.", "intervalBasis": "No normative interval exists; 12 months for standard laboratory or indoor use and 6 months for field, HVAC, or industrial environments is the recommendation published by calibration labs (Techmaster). Extension beyond 12 months should be justified by stable as-found history per ILAC-G24 methods.", "intervalFactors": [ "Field and HVAC use with temperature cycling and vibration roughly halves the defensible interval versus benchtop laboratory use (6 versus 12 months)", "Thermocouple-based probes drift faster than platinum resistance or thermistor probes, pushing toward the shorter end of the range", "Probe damage risk from handling, immersion in aggressive media, or use near range limits shortens the interval", "Regulated applications (food safety, pharma, medical) often fix the interval in SOPs regardless of drift history", "Consistent in-tolerance as-found results across cycles support extending toward 24 months" ], "standards": [ { "designation": "ASTM E2877", "title": "Standard Guide for Digital Contact Thermometers", "relevance": "Defines digital contact thermometers, their sensor types (PRT, thermistor, thermocouple), and nine accuracy classes over -200 C to 500 C" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval from as-found data and risk" } ], "sources": [ { "citation": "Digital Thermometer Calibration: From Setup to Certificate, Techmaster Electronics", "url": "https://techmaster.us/digital-thermometer-calibration/", "supports": "The interval claim (every 12 months for standard laboratory or indoor applications, every 6 months for field/HVAC/industrial), the test points (0/25/50/100 C), and the use of dry-block calibrators or liquid baths with NIST-traceable references" }, { "citation": "ASTM E2877, Standard Guide for Digital Contact Thermometers, ASTM International", "url": "https://www.astm.org/Standards/E2877.htm", "supports": "Definition of digital contact thermometers, covered sensor types, and the accuracy class framework used as acceptance criteria" }, { "citation": "SOP 25, Calibration of Liquid-in-Glass and Digital Thermometers, North Carolina Standards Laboratory (published via NIST Office of Weights and Measures)", "url": "https://www.nist.gov/system/files/documents/2021/07/26/NC%20SOP%2025%20Calibration%20of%20Liquid%20in%20Glass%20and%20Digital%20Thermometers.pdf", "supports": "Comparison calibration of digital thermometers against a reference thermometer with as-found recording" }, { "citation": "How to Calibrate a Digital Thermometer, Fluke Calibration", "url": "https://www.fluke.com/en-us/learn/blog/calibration/calibrate-digital-thermometer", "supports": "System calibration of probe plus readout by comparison in baths or dry-block calibrators" } ], "guideUrl": "https://gaugelog.com/calibration/digital-thermometer" }, { "id": "durometer", "name": "Durometer", "synonyms": [ "Shore durometer", "Shore hardness tester", "durometer hardness gage", "Shore A durometer", "Shore D durometer" ], "category": "hardness", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Spot-check readings on certified reference blocks before critical measurement campaigns, and recalibrate immediately after any drop, impact, or repair or when readings become inconsistent.", "intervalBasis": "No interval is mandated in the test method standards, so this is a manufacturer recommendation: Rex Gauge, a major durometer manufacturer, states the recommended calibration interval for all its durometers and test block kits is 1 year. Heavily used instruments are commonly calibrated more often.", "intervalFactors": [ "Frequency of use: production-line durometers used many times per day drift faster than lab units used occasionally", "Drops and impacts: a dropped handheld durometer can bend the indenter or shift the spring and needs immediate recalibration", "Deviations observed during routine checks on certified reference blocks justify shortening the cycle", "Indenter wear from testing abrasive or filled compounds changes geometry and readings", "Test block kits used for routine checks also age and need their own annual recalibration" ], "standards": [ { "designation": "ASTM D2240", "title": "Standard Test Method for Rubber Property - Durometer Hardness", "relevance": "Primary test method defining durometer types (A, D, and others), apparatus requirements, and spring force calibration requirements" }, { "designation": "ISO 48-4:2018", "title": "Rubber, vulcanized or thermoplastic - Determination of hardness - Part 4: Indentation hardness by durometer method (Shore hardness)", "relevance": "International Shore hardness method for A, D, AO, and AM scales, defining the instrument requirements the calibration must satisfy" }, { "designation": "ISO 18898:2016", "title": "Rubber - Calibration and verification of hardness testers", "relevance": "Dedicated calibration and verification procedure for durometers of types A, D, AO, and AM and IRHD instruments" } ], "sources": [ { "citation": "Rex Gauge Company, \"Service / Calibration\" (manufacturer calibration page)", "url": "https://www.durometer.com/repair-calibration/", "supports": "The interval: 'The recommended calibration interval for all Rex Gauge durometers and durometer test block kits is 1 year.'" }, { "citation": "ISO 18898:2016, Rubber - Calibration and verification of hardness testers, International Organization for Standardization", "url": "https://www.iso.org/standard/65920.html", "supports": "Existence of a dedicated calibration and verification procedure covering type A, D, AO, and AM durometers" }, { "citation": "ISO 48-4:2018, Rubber, vulcanized or thermoplastic - Determination of hardness - Part 4: Indentation hardness by durometer method (Shore hardness), International Organization for Standardization", "url": "https://www.iso.org/standard/74969.html", "supports": "Shore hardness scales covered (A, D, AO, AM) and instrument requirements" }, { "citation": "ASTM D2240, Standard Test Method for Rubber Property - Durometer Hardness, ASTM International", "url": "https://store.astm.org/d2240-15r21.html", "supports": "The governing US test method for durometer hardness and its apparatus requirements" } ], "guideUrl": "https://gaugelog.com/calibration/durometer" }, { "id": "extensometer", "name": "Extensometer", "synonyms": [ "extensometer system", "clip-on extensometer", "video extensometer", "COD gage", "strain extensometer" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 18 }, "usageBasedInterval": "Calibrate before and after any single test expected to last longer than 18 months (ISO 9513), and reverify after repair, overextension, or relocation of the test system; verification should cover the gauge length and measuring range actually used, as installed.", "intervalBasis": "ISO 9513:2012 states that under normal conditions calibration is recommended at intervals of approximately 12 months and that the interval shall not exceed 18 months, except for tests running longer than 18 months, where the system is calibrated before and after the test.", "intervalFactors": [ "Number of tests run and frequency of mounting/demounting, since clip-on knife edges and arms wear and shift with use", "Type of extensometer system: contacting clip-on units drift differently from video or laser non-contacting systems", "Class required by the test standards in use; tighter classes (ISO Class 0.2/0.5, ASTM Class A/B-1) warrant more frequent verification", "Long-term creep and stress relaxation programs, where ISO 9513 notes a three year interval based on practical experience with ISO 204 testing", "Any suspected mechanical damage, overextension beyond travel, or repair, which triggers immediate recalibration" ], "standards": [ { "designation": "ISO 9513:2012", "title": "Metallic materials - Calibration of extensometer systems used in uniaxial testing", "relevance": "Primary calibration method and classification standard; it sets the recommended 12 month and maximum 18 month calibration interval." }, { "designation": "ASTM E83", "title": "Standard Practice for Calibration, Verification, and Classification of Extensometer Systems", "relevance": "US practice for calibration, verification, and class assignment (Class A, B-1, B-2, C, D, E) of extensometer systems." } ], "sources": [ { "citation": "ISO 9513:2012, Metallic materials - Calibration of extensometer systems used in uniaxial testing, ISO", "url": "https://cdn.standards.iteh.ai/samples/41619/08d513e1f44e4ffbbefa326b7a70b21d/ISO-9513-2012.pdf", "supports": "Backs the interval claim directly: recommends calibration at intervals of approximately 12 months, not to exceed 18 months, with the before/after rule for longer tests and the three year note for long-term creep testing." }, { "citation": "ASTM E83, Standard Practice for Calibration, Verification, and Classification of Extensometer Systems, ASTM International", "url": "https://store.astm.org/standards/e83", "supports": "Backs the ASTM classification scheme and the calibration/verification procedure elements." }, { "citation": "NextGen Material Testing, \"Understanding ASTM E83 and ISO 9513 Standards for Extensometers and COD Gages\"", "url": "https://www.nextgentest.com/blog/understanding-astm-e83-and-iso-9513-standards-for-extensometers-and-cod-gages/", "supports": "Backs the class systems (ISO number classes vs ASTM letter classes), relative and fixed error limits, and the requirement to verify as installed at the gauge length and range of interest." } ], "guideUrl": "https://gaugelog.com/calibration/extensometer" }, { "id": "feeler-gauge", "name": "Feeler Gauge", "synonyms": [ "feeler gage", "thickness gauge", "blade gauge", "feeler stock", "gap gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "intervalBasis": "No standard sets a normative calibration interval for feeler gauges. Calibration providers commonly recommend recalibrating every 6 to 12 months; Cross Precision Measurement states that calibrating a feeler gage every 6-12 months is often recommended, with the final interval a risk-based user decision per the ILAC-G24 / OIML D 10 methodology.", "intervalFactors": [ "Frequency of blade insertion into tight gaps, which wears and thins the working end of each blade", "Use on abrasive or dirty surfaces (engine work, shop-floor setup) versus clean inspection-room use", "Criticality of the clearances checked, for example valve lash or safety-relevant machine clearances", "Physical condition history: kinked, bent, or corroded blades need replacement rather than interval extension", "As-found results from previous calibrations showing whether blades stay within their DIN 2275 tolerance class" ], "standards": [ { "designation": "DIN 2275:2014", "title": "Feeler gauges", "relevance": "Product standard for steel feeler gauges: dimensions, thickness tolerances (tolerance classes TC1 and TC2), minimum hardness of (420 +/- 50) HV 5, and marking requirements used as acceptance criteria at calibration." }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories", "relevance": "Provides the risk-based methodology for setting and adjusting the recalibration interval, since no feeler gauge standard prescribes one." } ], "sources": [ { "citation": "Cross Precision Measurement (Cross Company), \"Feeler Gauge Calibration With Certificate\", ISO/IEC 17025 accredited calibration service page", "url": "https://www.crossco.com/services/calibration/dimensional/feeler-gauge-calibration/", "supports": "Backs the interval claim: states it is often recommended to calibrate a feeler gage every 6-12 months. Also backs the procedure: measurements at multiple test points throughout the range of the feeler gage set, readings at a minimum of four test points, and NIST-traceable standards." }, { "citation": "DIN 2275:2014-03, Feeler gauges, DIN (Deutsches Institut fuer Normung)", "url": "https://webstore.ansi.org/standards/din/din22752014", "supports": "Backs the product standard listing: dimensions, tolerance classes TC1 and TC2, minimum Vickers hardness of (420 +/- 50) HV 5, and marking requirements used as acceptance criteria." }, { "citation": "ILAC-G24 / OIML D 10, Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories, ILAC and OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Backs the intervalBasis framing that calibration intervals are risk-based user decisions, initially set from manufacturer recommendations and adjusted using the methods described in the guide." } ], "guideUrl": "https://gaugelog.com/calibration/feeler-gauge" }, { "id": "flow-meter", "name": "Flow Meter", "synonyms": [ "flowmeter", "flow gauge", "turbine flow meter", "electromagnetic flow meter", "ultrasonic flow meter", "mag meter" ], "category": "flow", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Many operators schedule by totalized throughput or operating hours rather than calendar time, and trigger recalibration after fluid changes, process upsets, or suspected damage or coating.", "intervalBasis": "No instrument-wide normative interval exists; 12 months is the interval commonly recommended by calibration providers and manufacturers across meter types (for example electromagnetic, turbine, and positive displacement meters are typically calibrated every 12 months, extendable to 18 to 24 months in stable service). The manufacturer's stated minimum takes precedence where given.", "intervalFactors": [ "Dirty, abrasive, or corrosive fluids wear turbine rotors and coat electrodes or transducers, shortening the interval versus clean stable liquids", "Custody transfer, billing, or dosing applications carry financial and regulatory risk that justifies tighter intervals than trend-only indication", "Stable fluid composition, temperature, and pressure allow extension to 18 to 24 months for electromagnetic, turbine, and positive displacement types", "Meters with moving parts (turbine, positive displacement) drift faster mechanically than no-moving-part designs (electromagnetic, ultrasonic)", "As-found meter factor shifts between calibrations are the primary data for lengthening or shortening the cycle per ILAC-G24 methods" ], "standards": [ { "designation": "ISO 4185:1980", "title": "Measurement of liquid flow in closed conduits - Weighing method", "relevance": "Primary gravimetric calibration method: mass of liquid collected in a weighing tank over a known time interval" }, { "designation": "ISO 8316:1987", "title": "Measurement of liquid flow in closed conduits - Method by collection of the liquid in a volumetric tank", "relevance": "Primary volumetric calibration method for liquid flow meters" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for adjusting recalibration intervals from as-found data and risk" } ], "sources": [ { "citation": "Calibration Cycles of Different Flow Meters: An Overview, Just Measure It (zeroinstrument.com)", "url": "https://zeroinstrument.com/calibration-cycles-of-different-flow-meters-an-overview/", "supports": "The 12-month typical interval for electromagnetic, turbine, and positive displacement flow meters, with extension to 18 to 24 months in stable service (interval, range, and interval factors)" }, { "citation": "How Often Should Ultrasonic Flowmeters Be Calibrated?, Integrated Process Solutions (ips-us.com)", "url": "https://ips-us.com/how-often-should-ultrasonic-flowmeters-be-calibrated-for-optimal-performance/", "supports": "12-month calibration under standard operating conditions for ultrasonic flow meters (interval claim)" }, { "citation": "Related Metrology Standards, Fluid Metrology Group, NIST", "url": "https://www.nist.gov/pml/sensor-science/fluid-metrology/related-metrology-standards", "supports": "Existence and role of ISO 4185 (weighing method) and ISO 8316 (volumetric tank method) as primary liquid flow calibration standards" }, { "citation": "Guidelines on Calibration of Flow Meters, UNIDO", "url": "https://hub.unido.org/sites/default/files/publications/Guidelines%20on%20Calibration%20of%20Flow%20meters.pdf", "supports": "Calibration procedure elements: gravimetric and volumetric reference methods and master meter comparison" } ], "guideUrl": "https://gaugelog.com/calibration/flow-meter" }, { "id": "force-gauge", "name": "Force Gauge", "synonyms": [ "force gage", "push-pull gauge", "digital force gauge", "tension and compression gauge", "dynamometer" ], "category": "force-torque", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 12 }, "usageBasedInterval": "Recalibrate immediately after overload, drops, or repair; high-frequency daily use commonly moves the interval to 6 months, and many quality systems add periodic in-house checks with a known weight or reference load cell between calibrations.", "intervalBasis": "No standard sets a normative interval for handheld force gauges; annual calibration is the baseline recommended by manufacturers and calibration laboratories such as MRM Metrology, with 6 month or quarterly intervals recommended for high-use, harsh, or regulated applications.", "intervalFactors": [ "Usage intensity: gauges in daily production testing drift faster and may need 6 month or quarterly intervals", "Overload events: exceeding rated capacity in tension or compression can permanently shift the sensor and requires immediate recalibration", "Operating environment: temperature extremes, humidity, and contamination on portable field gauges shorten the interval", "Regulatory context such as pharmaceutical or medical device testing, which often mandates quarterly or semiannual checks", "Historical as-found drift from prior certificates, which supports lengthening or shortening the interval" ], "standards": [ { "designation": "ASTM E4", "title": "Standard Practices for Force Calibration and Verification of Testing Machines", "relevance": "Applied when a force gauge serves as the force-measuring system of a test stand or testing machine; verification at intervals of no more than 12 months is the recommended norm." }, { "designation": "ASTM E74", "title": "Standard Practices for Calibration and Verification for Force-Measuring Instruments", "relevance": "Governs the calibration of the reference force-measuring instruments (reference load cells) used to calibrate force gauges." } ], "sources": [ { "citation": "MRM Metrology, \"Force Gauge Calibration Frequency Guide\"", "url": "https://mrmmetrology.com/force-gauge-calibration-frequency/", "supports": "Backs the interval claim: annual calibration as the most common baseline, semiannual for high use or harsh environments, quarterly for critical or regulated applications, plus the factors that shift the interval." }, { "citation": "ASTM E4, Standard Practices for Force Calibration and Verification of Testing Machines, ASTM International", "url": "https://store.astm.org/e0004-21.html", "supports": "Backs the related standard for force verification when the gauge operates as a testing machine force system." }, { "citation": "ZwickRoell, \"ISO 7500-1, ASTM E4 Load Cell Calibration\" (calibration service page)", "url": "https://www.zwickroell.com/services/calibration/iso-7500-1-astm-e4-load-cell-calibration/", "supports": "Backs the statement that ASTM E4 and ISO 7500-1 recommend a verification interval of no more than 12 months for force-measuring systems on testing machines." } ], "guideUrl": "https://gaugelog.com/calibration/force-gauge" }, { "id": "gas-detector", "name": "Gas Detector", "synonyms": [ "gas monitor", "portable gas monitor", "multi-gas detector", "4-gas meter", "confined space monitor" ], "category": "chemical-analytical", "typicalIntervalMonths": 6, "intervalRangeMonths": { "min": 3, "max": 12 }, "usageBasedInterval": "Bump test (function check) or calibration check before each day's use per the ISEA position statement and OSHA guidance; a failed bump test triggers a full calibration before the instrument may be used.", "intervalBasis": "No standard sets a universal calendar interval; OSHA and ISEA guidance defers to manufacturer instructions, and most manufacturers recommend full calibration every 3 to 6 months, with Honeywell for example specifying every 180 days for most models under normal conditions. The daily verification burden sits in bump testing rather than in the calibration calendar.", "intervalFactors": [ "Exposure to sensor poisons and inhibitors such as silicones and sulfur compounds, which degrade catalytic and electrochemical sensors", "Over-range gas exposures or alarm events, after which a full calibration is required before further use", "Failed bump tests or calibration checks, which mandate an immediate full calibration", "Environmental stress from temperature extremes, high humidity, dust, and vibration in field service", "Life-safety criticality: monitors protecting confined space entry warrant conservative intervals and documented records", "Sensor age and remaining life, since electrochemical cells lose sensitivity as they deplete" ], "standards": [ { "designation": "IEC 60079-29-2:2015", "title": "Explosive atmospheres - Part 29-2: Gas detectors - Selection, installation, use and maintenance of detectors for flammable gases and oxygen", "relevance": "Gives recommended practice for use and maintenance of flammable gas and oxygen detectors, including how and how often verification and maintenance should be carried out and recorded" }, { "designation": "IEC 60079-29-1", "title": "Explosive atmospheres - Part 29-1: Gas detectors - Performance requirements of detectors for flammable gases", "relevance": "Performance requirements the detectors themselves must meet, referenced by the maintenance guidance in Part 29-2" } ], "sources": [ { "citation": "OSHA Safety and Health Information Bulletin SHIB 09-30-2013, Calibrating and Testing Direct-Reading Portable Gas Monitors, U.S. Occupational Safety and Health Administration", "url": "https://www.osha.gov/publications/shib093013", "supports": "Bump test or calibration check before each day's use, full calibration after a failed bump test, and removal from service after failed calibration; guidance defers interval specifics to manufacturer instructions" }, { "citation": "Recommended Calibration Timelines for Gas Detectors by Manufacturer, Ideal Calibrations", "url": "https://idealcalibrations.com/blog/recommended-calibration-timelines-for-gas-detectors-by-manufacturer/", "supports": "Interval claim: most manufacturers recommend full calibration every 3 to 6 months, with Honeywell specifying 180 days (6 months) for most models under normal conditions" }, { "citation": "ISEA Statement on Validation of Operation for Direct Reading Portable Gas Monitors, International Safety Equipment Association (summary by CAC Gas & Instrumentation)", "url": "https://cacgas.com.au/blog/isea-statement-on-validation-of-operation-for-direct-reading-portable-gas-monitors/", "supports": "ISEA position (updated 2010) that a bump test or calibration check should be conducted before each day's use in accordance with manufacturer instructions, and definitions of bump test versus calibration check versus full calibration" }, { "citation": "IEC 60079-29-2:2015, Explosive atmospheres - Part 29-2: Gas detectors - Selection, installation, use and maintenance of detectors for flammable gases and oxygen, IEC", "url": "https://webstore.ansi.org/standards/iec/iec6007929eden2015", "supports": "Standardized guidance on maintenance, verification frequency, and record keeping for flammable gas and oxygen detectors" } ], "guideUrl": "https://gaugelog.com/calibration/gas-detector" }, { "id": "gauge-block", "name": "Gauge Block", "synonyms": [ "gage block", "slip gauge", "Jo block", "block gauge", "Johansson gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Recalibrate outside the normal cycle after any drop or impact, visible scratches, corrosion, or wringing problems on the gauging surfaces, since surface damage invalidates the certified length.", "intervalBasis": "ISO 3650 and ASME B89.1.9 define grades and tolerances but no normative recalibration interval. Calibration providers commonly recommend 1-2 years: Accredited Labs states gage blocks should typically be calibrated every 1-2 years depending on usage frequency, environmental conditions, industry requirements, and historical performance, with heavily used working sets kept at the short end of that range and stable reference sets extended per ILAC-G24 / OIML D 10 methods.", "intervalFactors": [ "Usage frequency: working sets wrung daily wear at the gauging faces far faster than reference or master sets used only to calibrate other blocks", "Grade and role: calibration grade K / grade 00 masters kept in the lab typically run longer intervals than grade 1-2 shop working sets", "Handling and wringing practice, since each wringing cycle and any burr or scratch changes effective length at the sub-micrometer level", "Environment: temperature variation, humidity, and corrosive atmospheres degrade steel blocks; ceramic and carbide blocks are more stable", "As-found drift history at the previous calibrations, the primary input for extending or shortening the interval under ILAC-G24 / OIML D 10 methods" ], "standards": [ { "designation": "ISO 3650:1998", "title": "Geometrical Product Specifications (GPS) - Length standards - Gauge blocks", "relevance": "International standard defining gauge block design and metrological characteristics with limit deviations for calibration grade K and grades 0, 1, and 2; the acceptance criteria for calibration." }, { "designation": "ASME B89.1.9", "title": "Gage Blocks", "relevance": "US standard for precision gage blocks, defining grades (including 00, 0, AS-1, and AS-2) and tolerances used as calibration acceptance criteria in North America." } ], "sources": [ { "citation": "Accredited Labs, \"Why NIST Traceable Standards Matter for Gage Block Calibration\", accredited calibration laboratory blog", "url": "https://www.accreditedlabs.com/blog/why-nist-traceable-standards-matter-in-gage-block-calibration", "supports": "Backs the interval claim that gage blocks should typically be calibrated every 1-2 years depending on usage frequency, environmental conditions, industry requirements, and historical performance, and the traceability chain and comparison procedure description including cleaning, 20 degrees C stabilization, and calibration to ASME B89.1.9 and ISO 3650." }, { "citation": "Ted Doiron and John Beers, The Gauge Block Handbook, NIST Monograph 180 with Corrections, National Institute of Standards and Technology", "url": "https://emtoolbox.nist.gov/Publications/NISTMonograph180.pdf", "supports": "Backs the procedure outline: calibration by interferometry for master blocks and by mechanical comparison for transfer, wringing behavior, thermal handling, and measurement assurance practice." }, { "citation": "ISO 3650:1998, Geometrical Product Specifications (GPS) - Length standards - Gauge blocks, International Organization for Standardization", "url": "https://www.iso.org/standard/1241.html", "supports": "Backs the standards listing and acceptance criteria: grades K, 0, 1, 2 with limit deviations for nominal lengths 0.5 mm to 1000 mm." }, { "citation": "ANSI/ASME B89.1.9-2002, Gage Blocks, The American Society of Mechanical Engineers", "url": "https://webstore.ansi.org/standards/asme/ansiasmeb892002", "supports": "Backs the standards listing: the US gage block standard defining grades and tolerances used as calibration acceptance criteria." } ], "guideUrl": "https://gaugelog.com/calibration/gauge-block" }, { "id": "hardness-tester", "name": "Hardness Tester", "synonyms": [ "Rockwell hardness tester", "Brinell hardness tester", "Vickers hardness tester", "microhardness tester", "hardness testing machine" ], "category": "hardness", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 12, "max": 18 }, "usageBasedInterval": "Daily verification on a certified reference block each day the tester is used, and again whenever the anvil, test force, or indenter is changed (ASTM E18); direct verification after any repair, adjustment, or relocation.", "intervalBasis": "The verification schedule here is normative in the method standards: ISO 6508-2, ISO 6506-2, ISO 6507-2, and ASTM E18 require periodic indirect verification with calibrated reference blocks, which industry guidance for ASTM E18 and Nadcap describes as typically performed annually, with ASTM allowing up to 18 months between indirect verifications.", "intervalFactors": [ "Each hardness scale and test force in use must be verified separately, so multi-scale machines need broader (and often more frequent) verification work", "Failed daily verifications or drifting results on reference blocks trigger an immediate new indirect verification", "Any adjustment, modification, repair, or relocation of the machine requires direct verification before further use", "Heavy production use (continuous shifts) shortens the practical cycle; some aerospace suppliers verify far more often than annually", "Change of indenter, anvil, or test force always requires at least a daily verification before testing resumes", "Customer or accreditation requirements such as Nadcap heat-treatment audits may impose stricter schedules than the standard minimum" ], "standards": [ { "designation": "ISO 6508-2:2023", "title": "Metallic materials - Rockwell hardness test - Part 2: Verification and calibration of testing machines and indenters", "relevance": "Defines direct and indirect verification of Rockwell testers, including force, depth measurement, and cycle timing tolerances" }, { "designation": "ISO 6506-2:2017", "title": "Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines", "relevance": "Defines direct and indirect verification for Brinell testers and specifies when each verification type is required" }, { "designation": "ISO 6507-2:2018", "title": "Metallic materials - Vickers hardness test - Part 2: Verification and calibration of testing machines", "relevance": "Defines verification and calibration of Vickers machines, indenters, and the diagonal measuring system" }, { "designation": "ASTM E18", "title": "Standard Test Methods for Rockwell Hardness of Metallic Materials", "relevance": "Specifies direct, indirect, and daily verification of Rockwell hardness machines including verification timing" } ], "sources": [ { "citation": "Thermal Processing Magazine, \"ASTM E18 and Nadcap: Rockwell hardness testing\"", "url": "https://thermalprocessing.com/astm-e18-and-nadcap-rockwell-hardness-testing/", "supports": "The interval: indirect verification is typically performed annually; daily verification is performed each day before use and when anvil, test force, or indenter changes; direct verification triggers (new machine, failed indirect test, repairs or adjustments)" }, { "citation": "ISO 6508-2:2023, Metallic materials - Rockwell hardness test - Part 2: Verification and calibration of testing machines and indenters, International Organization for Standardization", "url": "https://www.iso.org/standard/83888.html", "supports": "Direct and indirect verification methods, force/depth/timing tolerances, and use of calibrated reference blocks" }, { "citation": "ASTM E18, Standard Test Methods for Rockwell Hardness of Metallic Materials, ASTM International", "url": "https://www.astm.org/Standards/E18.htm", "supports": "Three-tier verification scheme (direct, indirect, daily) for Rockwell machines, with indirect verification recommended every 12 months and required at intervals no longer than 18 months" }, { "citation": "EMCO-TEST, \"What is an indirect verification\" (hardness testing knowledge base)", "url": "https://www.emcotest.com/en/the-world-of-hardness-testing/hardness-know-how/calibration-standards/calibration/what-is-an-indirect-verification/", "supports": "Indirect verification determines machine accuracy through a series of measurements on calibrated test blocks" } ], "guideUrl": "https://gaugelog.com/calibration/hardness-tester" }, { "id": "height-gauge", "name": "Height Gauge", "synonyms": [ "height gage", "vernier height gauge", "digital height gauge", "dial height gauge", "electronic height gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Zero check on the surface plate before each measuring session; recalibrate immediately after tipping over, impact, or erratic slider movement", "intervalBasis": "ISO 13225 defines design and metrological characteristics but not a mandatory recalibration interval. The 12-month starting point is the typical interval cited by accredited calibration labs for standard industrial use (Techmaster), with 6 months for heavy-duty environments and 3 to 6 months in regulated industries; the final interval is a user decision per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Frequency of use for scribing and layout work, which wears the scriber tip and slider more than pure inspection use", "Condition and calibration status of the granite surface plate the gauge is used on, since plate flatness errors add directly to height results", "Transport between benches or plants; column instruments are vulnerable to shock and misalignment in transit", "Criticality of the measured features; regulated industries such as aerospace and medical typically shorten intervals to 3 to 6 months", "As-found history from previous calibrations, which supports extending or shortening the interval per ILAC-G24 methods" ], "standards": [ { "designation": "ISO 13225:2012", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Height gauges - Design and metrological characteristics", "relevance": "Primary international standard specifying design and metrological characteristics of analog and digital height gauges measured perpendicular to a surface plate" }, { "designation": "JIS B 7517:2018", "title": "Vernier, dial and digital height gauges", "relevance": "Japanese Industrial Standard based on ISO 13225:2012 (modified), specifying design and accuracy requirements for vernier, dial, and digital height gauges" } ], "sources": [ { "citation": "Techmaster Electronics, \"Height Gauge Calibration in Quality Management\" (ISO/IEC 17025 accredited lab service page)", "url": "https://techmaster.us/height-gauge-calibration/", "supports": "The 12-month typical interval for standard industrial use, 6 months for heavy-duty environments and 3 to 6 months for regulated industries, the reference to ISO 13225, and the use of certified Grade 0 gauge blocks under controlled conditions" }, { "citation": "ISO 13225:2012, Geometrical product specifications (GPS) - Dimensional measuring equipment - Height gauges - Design and metrological characteristics, International Organization for Standardization", "url": "https://www.iso.org/standard/42893.html", "supports": "Standard designation, title, and scope covering height gauges with analog or digital indication for measurements perpendicular to a surface plate" }, { "citation": "JIS B 7517:2018, Vernier, dial and digital height gauges, Japanese Standards Association", "url": "https://webstore.ansi.org/standards/jis/jis75172018", "supports": "Standard designation and title, and its correspondence to ISO 13225:2012 as the Japanese height gauge standard" } ], "guideUrl": "https://gaugelog.com/calibration/height-gauge" }, { "id": "hydrometer", "name": "Hydrometer", "synonyms": [ "hydrometer gage", "density hydrometer", "specific gravity hydrometer", "thermohydrometer", "areometer" ], "category": "mass-volume", "typicalIntervalMonths": 24, "intervalRangeMonths": { "min": 12, "max": 36 }, "usageBasedInterval": "Recalibrate after any suspected damage, chipping, or contamination of the glass, and immediately if a reading is questioned in a dispute or fiscal measurement.", "intervalBasis": "No international standard sets a fixed hydrometer recalibration interval; the decision rests with the user. Specialist density calibration labs recommend calibrating hydrometers when new, again after one year of regular ambient use, then every two to three years; hydrometers used above or below ambient temperature should be calibrated annually.", "intervalFactors": [ "Operating temperature: hydrometers used above or below ambient should be calibrated annually rather than every 2-3 years", "Fiscal or custody-transfer use: measurements with financial consequence justify tighter intervals", "Scale precision: high-resolution instruments that read to more decimal places show drift sooner and need closer control", "Handling risk: glass instruments subject to breakage, chipping, or scale-paper shift require reverification", "Liquid aggressiveness: corrosive or staining liquids can attack the glass or scale and shorten the interval", "Frequency of use and cleaning cycles that can dislodge ballast or the internal scale" ], "standards": [ { "designation": "ASTM E100", "title": "Standard Specification for ASTM Hydrometers", "relevance": "Specifies scale ranges, graduations, and tolerances for glass hydrometers of the constant-mass, variable-displacement type." }, { "designation": "NIST SP 250-78", "title": "NIST Calibration Services for Hydrometers", "relevance": "Describes NIST's traceable hydrometer calibration service and the Cuckow (hydrostatic weighing) reference method." } ], "sources": [ { "citation": "ASTM E100, Standard Specification for ASTM Hydrometers, ASTM International", "url": "https://store.astm.org/standards/e100", "supports": "Scale ranges, graduation, tolerances, and constant-mass variable-displacement construction of glass hydrometers." }, { "citation": "NIST Special Publication 250-78r1, NIST Calibration Services for Hydrometers, National Institute of Standards and Technology", "url": "https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.250-78r1.pdf", "supports": "Cuckow hydrostatic weighing and comparison calibration methods and traceability." }, { "citation": "H&D Fitzgerald, How Often Should I Calibrate? (density metrology calibration lab guidance)", "url": "https://www.density.co.uk/papers/how-often-should-i-calibrate", "supports": "Interval guidance: calibrate hydrometers when new, after one year of regular ambient use, then every two to three years; annually for hydrometers used above or below ambient temperature; no international standard fixes the interval." } ], "guideUrl": "https://gaugelog.com/calibration/hydrometer" }, { "id": "hygrometer", "name": "Hygrometer", "synonyms": [ "humidity meter", "RH meter", "thermohygrometer", "humidity probe", "dew point meter", "relative humidity sensor" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Recalibrate after known chemical exposure, condensation events, or sensor element replacement, in addition to the time-based schedule.", "intervalBasis": "No standard mandates a fixed interval. Vaisala, a leading humidity instrument manufacturer, states that the long term stability of its HUMICAP sensors usually requires only an annual calibration, and that operating conditions can shorten this, so 12 months is the common manufacturer-recommended starting point, adjusted per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Continuous operation at high humidity or near condensation, which accelerates capacitive sensor drift", "Exposure to chemical vapors and outgassing (e.g. in test chambers or cleanrooms) that causes humidity drift, slower response, and hysteresis", "Criticality of the application: stability chambers, calibration labs, and GxP storage areas typically require 6 to 12 months", "As-found drift history at low, mid, and high RH points from previous certificates", "Temperature extremes at the installation point, since RH accuracy is temperature dependent" ], "standards": [ { "designation": "ASTM E104", "title": "Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions", "relevance": "Defines the saturated salt solution method for generating constant relative humidity environments from dryness to near saturation at temperatures from 0 to 50 C, explicitly applicable to hygrometer calibration" }, { "designation": "NIST SP 250-83", "title": "Calibration of Hygrometers with the Hybrid Humidity Generator", "relevance": "NIST measurement service documentation describing traceable hygrometer calibration with a two-pressure/hybrid humidity generator" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and reviewing the recalibration interval, since no instrument-specific normative interval exists" } ], "sources": [ { "citation": "ASTM E104-20a, Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions, ASTM International", "url": "https://store.astm.org/e0104-20a.html", "supports": "Saturated salt solution method for hygrometer calibration, applicable range (dryness to near saturation, 0 to 50 C), and closed-container requirement in the procedure" }, { "citation": "NIST Special Publication 250-83, Calibration of Hygrometers with the Hybrid Humidity Generator, National Institute of Standards and Technology", "url": "https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication250-83.pdf", "supports": "Traceable humidity generator calibration method (two-pressure operation for dew/frost points at or above -10 C) referenced in the procedure and equipment list" }, { "citation": "Vaisala, Humidity measurement in test chambers - questions and answers (application note)", "url": "https://www.vaisala.com/en/application-note/humidity-measurement-test-chambers-questions-and-answers", "supports": "Interval claim: states HUMICAP sensor long term stability usually requires only an annual calibration; also chemical contamination effects (drift, response time, hysteresis) used in interval factors" } ], "guideUrl": "https://gaugelog.com/calibration/hygrometer" }, { "id": "industrial-scale", "name": "Industrial Scale", "synonyms": [ "floor scale", "platform scale", "bench scale", "pallet scale", "industrial weighing scale" ], "category": "mass-volume", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 1, "max": 12 }, "usageBasedInterval": "Daily or per-shift zero check and a quick span check with a known test weight are common practice; recalibrate after relocation, overload events, load cell or indicator repair, or a failed routine check.", "intervalBasis": "No single normative interval exists; Mettler-Toledo states floor scales are typically calibrated once a year with the actual frequency set by the site's SOP, while industry guidance tiers the cycle down to 6 months for busy warehouse scales, quarterly for production batching, and monthly for high-precision pharmaceutical use. Legal-for-trade devices are additionally verified under the state weights and measures program per NIST Handbook 44.", "intervalFactors": [ "Legal-for-trade status: scales used in commerce must hold NTEP certification and stay within NIST Handbook 44 tolerances, with verification schedules set by the state weights and measures authority", "Process criticality: batching, ingredient dosing, and quality control weighing justify quarterly cycles versus annual for occasional-use scales", "Environment: temperature swings, moisture and washdown, dust, and shock loading from forklifts and pallet jacks accelerate load cell drift", "Usage intensity: heavy daily loading near capacity shortens the defensible interval compared to light occasional use", "Installation changes: relocating the scale or disturbing its foundation or leveling invalidates the previous calibration", "As-found history: repeated out-of-tolerance findings at annual calibration require a shorter cycle per ILAC-G24 methods" ], "standards": [ { "designation": "NIST Handbook 44", "title": "Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices (NIST, published annually)", "relevance": "The legal metrology requirements and tolerances applied to commercial weighing devices in the United States, adopted by state weights and measures authorities" }, { "designation": "OIML R 76-1", "title": "Non-automatic weighing instruments - Part 1: Metrological and technical requirements - Tests", "relevance": "International accuracy classification and maximum permissible errors for non-automatic weighing instruments, used for type approval and verification outside the US" }, { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Framework for accredited on-site scale calibration with traceable test weights and reported uncertainty" } ], "sources": [ { "citation": "Mettler-Toledo, \"Calibration and Certificates\" for floor scales and heavy-duty industrial scales (METTLER TOLEDO)", "url": "https://www.mt.com/us/en/home/products/Industrial_Weighing_Solutions/floor-scales-heavy-duty/service/compliance/calibration-and-certificates.html", "supports": "The 12 month typical interval: floor scales are typically calibrated once a year, with frequency depending on the user's SOP and process requirements" }, { "citation": "Scale Blog, \"How often should industrial scales be calibrated?\" (Scale Blog, industrial weighing guidance site)", "url": "https://scaleblog.com/how-often-should-industrial-scales-be-calibrated/", "supports": "The interval range and tiering: annual only for infrequently used scales, 6 months for warehouse/shipping scales, quarterly for production batching and QC, monthly for high-precision pharmaceutical use, plus the usage and environment factors" }, { "citation": "NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, 2026 Edition (NIST)", "url": "https://www.nist.gov/publications/nist-handbook-44-specifications-tolerances-and-other-technical-requirements-weighing-18", "supports": "Legal metrology tolerances and technical requirements for commercial weighing devices, adopted by state weights and measures authorities, used as acceptance criteria for legal-for-trade scales" }, { "citation": "Cross Company, \"Are Your Scales Legal-for-Trade? Here's Why It Matters\" (Cross Company)", "url": "https://www.crossco.com/resources/articles/are-your-scales-legal-for-trade/", "supports": "That legal-for-trade scales must comply with NIST Handbook 44, are NTEP certified, and are tested by state inspectors, which drives the additional verification layer described" } ], "guideUrl": "https://gaugelog.com/calibration/industrial-scale" }, { "id": "infrared-thermometer", "name": "Infrared Thermometer", "synonyms": [ "IR thermometer", "non-contact thermometer", "radiation thermometer", "spot pyrometer", "laser thermometer" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Verify against a reference source or IR comparator after any drop or lens contamination and before critical measurement campaigns, in addition to the time-based schedule.", "intervalBasis": "No standard mandates a fixed interval; ASTM E2847 defines the calibration method, not the frequency. Calibration providers report that manufacturers such as Fluke recommend recalibration at least once a year, with more frequent calibration for heavy use or harsh service, so 12 months is the usual starting point, adjusted using the risk-based interval methodology of ILAC-G24 / OIML D 10.", "intervalFactors": [ "Frequency of use and whether readings feed critical process or safety decisions (food safety, electrical inspection)", "Exposure to dust, smoke, or vapor that contaminates the lens and shifts the radiometric response", "Mechanical or thermal shock from drops and rapid ambient swings in field service", "As-found drift history at the low, mid, and high points of the calibrated range", "Regulatory or QA program requirements (e.g. HACCP or pharma programs often force 6 to 12 months)" ], "standards": [ { "designation": "ASTM E2847", "title": "Standard Test Method for Calibration and Accuracy Verification of Wideband Infrared Thermometers", "relevance": "Primary method standard: defines test setup, blackbody source use, measurement geometry, and uncertainty calculation for calibrating wideband IR thermometers below 1000 C" }, { "designation": "ASTM E2758", "title": "Standard Guide for Selection and Use of Wideband, Low Temperature Infrared Thermometers", "relevance": "Companion guide covering correct use, field-of-view, emissivity, and error sources that the calibration must account for" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval, since no normative interval exists for IR thermometers" } ], "sources": [ { "citation": "ASTM E2847-21, Standard Test Method for Calibration and Accuracy Verification of Wideband Infrared Thermometers, ASTM International", "url": "https://store.astm.org/e2847-21.html", "supports": "Governing method standard; blackbody source selection, measurement geometry, and uncertainty evaluation steps in the procedure outline" }, { "citation": "Applied Technical Services, Fluke IR Thermometer Calibration (calibration service page)", "url": "https://atslab.com/calibration/environmental-equipment/fluke-ir-thermometer-calibration/", "supports": "Interval claim: states manufacturers like Fluke recommend IR thermometers be recalibrated at least once a year; also 24 hour acclimation, calibration at five or more points across roughly -30 C to 500 C, and as-found/as-left certificate practice" }, { "citation": "Fluke Calibration, Guide to IR Thermometer Calibration (fluke.com learn blog)", "url": "https://www.fluke.com/en-us/learn/blog/temperature-calibration/ir-thermometer-calibration", "supports": "Cavity vs flat-plate source selection, radiometric vs contact transfer, emissivity uncertainty (difficulty of controlling emissivity to within 0.01), and field-of-view/distance guidance (source diameter at least 3 times the spot size) in the procedure" }, { "citation": "ILAC-G24 / OIML D 10, Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Interval basis framing: recalibration intervals are risk-based user decisions reviewed by methods such as staircase adjustment and control charts" } ], "guideUrl": "https://gaugelog.com/calibration/infrared-thermometer" }, { "id": "insulation-resistance-tester", "name": "Insulation Resistance Tester", "synonyms": [ "megohmmeter", "insulation tester", "megger", "IR tester", "insulation multimeter" ], "category": "electrical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Recalibrate immediately after a drop or impact, after repair or firmware update, or after any failed pre-use check of leads and battery, regardless of the calendar interval.", "intervalBasis": "No standard mandates an interval for insulation testers. Twelve months is the cycle leading manufacturers such as Fluke and Megger recommend and that accredited labs like Techmaster Electronics apply as the default, shortened to about 6 months for heavy field use; the final interval is a risk-based user decision per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Heavy portable field use with frequent transport, drops, and lead wear pushes the interval toward 6 months", "Safety criticality: results are used to declare installations and machines electrically safe, so out-of-tolerance risk is high consequence", "Test voltage drift has leveraged effect: a small error in generated voltage produces a much larger error in indicated insulation resistance", "Regular use of the highest voltage ranges (5 kV and 10 kV testers) stresses internal HV components and supports shorter intervals", "As-found history: repeated in-tolerance results at 12 months can justify extension, out-of-tolerance results require shortening per ILAC-G24 methods" ], "standards": [ { "designation": "IEC 61557-2", "title": "Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC - Equipment for testing, measuring or monitoring of protective measures - Part 2: Insulation resistance", "relevance": "Defines performance and accuracy requirements for insulation resistance measuring equipment; calibration verifies the instrument still meets these requirements" }, { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Framework under which accredited calibration of insulation testers is performed and traceability is demonstrated" }, { "designation": "ILAC-G24 / OIML D 10", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval, since no instrument-specific normative interval exists" } ], "sources": [ { "citation": "Techmaster Electronics, \"Megohmmeter Calibration: Ensuring Reliable Insulation Resistance Testing\" (ISO/IEC 17025 accredited calibration laboratory)", "url": "https://techmaster.us/megohmmeter-calibration/", "supports": "The 12 month typical interval (manufacturers Fluke and Megger recommend a 12-month cycle), the 6 month interval for heavy field use, recalibration after impact or firmware update, the reference resistance standards from 10 MOhm to 10 TOhm, and the as-found/as-left procedure steps" }, { "citation": "IEC 61557-2, Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC - Equipment for testing, measuring or monitoring of protective measures - Part 2: Insulation resistance (IEC)", "url": "https://standards.globalspec.com/std/13390227/iec-61557-2", "supports": "Existence, designation, and scope of the product standard governing insulation resistance measuring equipment" }, { "citation": "Fluke Calibration, 5320A Multifunction Electrical Tester Calibrator product page (Fluke)", "url": "https://www.fluke.com/en-us/product/calibration-tools/electrical-calibration/electrical-calibrators/5320a", "supports": "Reference equipment used: variable resistance 10 kOhm to 10 GOhm for testers up to 1 kV, extension to 10 TOhm via 10 kV adapter, and measurement of the tester's high-voltage output" }, { "citation": "ILAC-G24 / OIML D 10:2022, Guidelines for the determination of recalibration intervals of measuring equipment (ILAC and OIML)", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "The statement that the calibration interval is a risk-based user decision and the methods for adjusting it from as-found history" } ], "guideUrl": "https://gaugelog.com/calibration/insulation-resistance-tester" }, { "id": "lcr-meter", "name": "LCR Meter", "synonyms": [ "impedance meter", "LCR bridge", "RLC meter", "capacitance meter", "impedance analyzer" ], "category": "electrical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Perform open/short (and load, where supported) fixture compensation before measurement sessions and whenever the fixture, cable length, or test frequency setup changes.", "intervalBasis": "No standard sets a normative interval for LCR meters. Annual calibration is the standard recommendation from accredited calibration labs such as Techmaster Electronics, shortened to about 6 months for harsh environments or heavy use, and Keysight publishes model-specific recommended intervals of 6 to 36 months for its test instruments; the working interval is a risk-based user decision per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Component tolerance grading: meters used to grade tight-tolerance capacitors or inductors for production need shorter cycles than general troubleshooting units", "Test frequency coverage: instruments used across wide frequency ranges (e.g. up to 1 MHz or 2 MHz) have more accuracy terms that can drift than single-frequency use at 1 kHz", "Fixture and cabling wear: heavy use of Kelvin clips and test fixtures degrades contact repeatability and increases residual impedance errors", "Harsh environment or heavy daily use supports a 6 month cycle per calibration lab guidance", "As-found history against the manufacturer accuracy specification, evaluated per ILAC-G24 methods, drives extension or reduction" ], "standards": [ { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Accredited LCR meter calibration with traceable impedance standards and reported uncertainty is performed under this standard" }, { "designation": "ILAC-G24 / OIML D 10", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting the recalibration interval, since no LCR-meter-specific normative interval exists" } ], "sources": [ { "citation": "Techmaster Electronics, \"LCR Meter Calibration For ISO 17025 Compliance\" (ISO/IEC 17025 accredited calibration laboratory)", "url": "https://techmaster.us/lcr-meter-calibration/", "supports": "The 12 month typical interval (annual is the standard recommendation), the 6 month interval for harsh environments or heavy use, and the as-found/as-left procedure structure" }, { "citation": "IET Labs, Application Note 035119: Calibration of 7000 Series Precision LCR Meters (IET Labs)", "url": "https://www.ietlabs.com/pdf/application_notes/035119%207000-09%20Calibration%20Kit%20A1.pdf", "supports": "Procedure and equipment claims: resistance standards as the primary calibration references (four resistance standards suffice for all measurement ranges), standard capacitors used to check for non-linearity and noise, and the need to match test frequency to the standard's certified frequency" }, { "citation": "Keysight Technologies, Technical Support Knowledge Center: \"What is the recommended calibration interval for my Keysight instrument?\" (Keysight)", "url": "https://docs.keysight.com/kkbopen/what-is-the-recommended-calibration-interval-for-my-keysight-instrument-678073287.html", "supports": "Manufacturer interval guidance: Keysight recommends model-specific calibration intervals of 6, 12, 24, or 36 months for its instruments, which brackets the interval range given" } ], "guideUrl": "https://gaugelog.com/calibration/lcr-meter" }, { "id": "liquid-in-glass-thermometer", "name": "Liquid-in-Glass Thermometer", "synonyms": [ "glass thermometer", "mercury-in-glass thermometer", "spirit thermometer", "LiG thermometer", "ASTM thermometer" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Single-point ice point (0 C) checks between full calibrations: as often as monthly for new thermometers, extending to every two months and then annually as stability is demonstrated (NIST SP 1088).", "intervalBasis": "Based on NIST SP 1088: routine ice-point checks start as often as monthly for new thermometers, and once stability is demonstrated the recalibration check interval extends, with once or twice a year recommended as the minimum between calibration checks. This is NIST guidance rather than a normative standard requirement.", "intervalFactors": [ "New thermometers and those with large bulbs show the greatest bulb changes and need frequent ice-point checks at first (NIST SP 1088)", "Use above roughly 200 C accelerates permanent bulb changes and shortens the interval", "A stable ice-point history over successive checks justifies extending the interval per NIST SP 1088", "Mechanical shock or thermal cycling can separate the liquid column, requiring inspection and revalidation regardless of schedule", "Use as a reference or in regulated test methods (ASTM test methods specifying E1 thermometers) raises criticality" ], "standards": [ { "designation": "ASTM E1", "title": "Standard Specification for ASTM Liquid-in-Glass Thermometers", "relevance": "Defines construction, ranges, and maximum scale errors for ASTM liquid-in-glass thermometers" }, { "designation": "ASTM E77", "title": "Standard Test Method for Inspection and Verification of Thermometers", "relevance": "The test method for visual/dimensional inspection and scale accuracy verification of liquid-in-glass thermometers specified in E1" }, { "designation": "NIST SP 1088", "title": "Maintenance, Validation, and Recalibration of Liquid-in-Glass Thermometers", "relevance": "NIST guidance on ice-point checks, recalibration intervals, and handling of liquid-in-glass thermometers" } ], "sources": [ { "citation": "NIST Special Publication 1088, Maintenance, Validation, and Recalibration of Liquid-in-Glass Thermometers, NIST", "url": "https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=900914", "supports": "The interval guidance (ice point checks monthly for new thermometers, extending to once or twice a year as the minimum between calibration checks) and the factors that drive recalibration frequency (bulb size, use above 200 C, thermometer age)" }, { "citation": "ASTM E77, Standard Test Method for Inspection and Verification of Thermometers, ASTM International", "url": "https://www.astm.org/Standards/E77.htm", "supports": "The verification procedure (visual and dimensional inspection, scale accuracy testing) and its link to the E1 maximum scale errors used as acceptance criteria" }, { "citation": "SOP 25, Calibration of Liquid-in-Glass and Digital Thermometers, North Carolina Standards Laboratory (published via NIST Office of Weights and Measures)", "url": "https://www.nist.gov/system/files/documents/2021/07/26/NC%20SOP%2025%20Calibration%20of%20Liquid%20in%20Glass%20and%20Digital%20Thermometers.pdf", "supports": "The comparison calibration procedure in stirred baths against a reference thermometer with as-found recording" } ], "guideUrl": "https://gaugelog.com/calibration/liquid-in-glass-thermometer" }, { "id": "load-cell", "name": "Load Cell", "synonyms": [ "force transducer", "load sensor", "strain gauge load cell", "force-proving instrument", "weighing cell" ], "category": "force-torque", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 26 }, "usageBasedInterval": "Recalibrate immediately after overload beyond rated capacity, shock damage, or repair; reference cells should also be checked after transport, and new instruments are typically recalibrated after the first year to establish stability before any interval extension.", "intervalBasis": "For load cells used as force-proving instruments, ISO 376 caps the validity of the calibration certificate at 26 months, and ASTM E74 permits a two year recalibration interval only when stability of 0.032% (Class AA range) or 0.16% (Class A range) is demonstrated between calibrations; 12 months is the common starting interval until that drift history exists.", "intervalFactors": [ "Demonstrated stability between successive calibrations: ASTM E74 explicitly conditions the two year interval on meeting its stability criteria", "Role of the cell: a reference (force-proving) transducer used to calibrate other equipment needs a tighter, standards-capped interval than a process weighing cell", "Overloads, shock loads, or side loading in service, which can shift zero and span and require immediate recalibration", "Creep and temperature sensitivity of the specific cell design and its compensation quality", "Frequency of transport and reinstallation, since mounting conditions and cabling changes affect output" ], "standards": [ { "designation": "ISO 376", "title": "Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines", "relevance": "Governs calibration and classification of load cells used as force-proving instruments and caps certificate validity at 26 months." }, { "designation": "ASTM E74", "title": "Standard Practices for Calibration and Verification for Force-Measuring Instruments", "relevance": "US practice for calibrating force-measuring instruments, defining the lower limit factor, Class A/AA verified ranges, and the stability-conditioned recalibration interval of up to two years." }, { "designation": "ISO 7500-1", "title": "Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines", "relevance": "The testing machine verification standard whose force checks rely on load cells calibrated per ISO 376." } ], "sources": [ { "citation": "Morehouse Instrument Company, \"ASTM E74 is Not the Same as ISO 376\"", "url": "https://mhforce.com/astm-e74-is-not-the-same-as-iso-376/", "supports": "Backs the interval claims: ISO 376 section 8.3.2 caps calibration certificate validity at 26 months, and ASTM E74 section 11 assigns a two year interval only when 0.032% (Class AA) or 0.16% (Class A) stability is demonstrated." }, { "citation": "ASTM E74, Standard Practices for Calibration and Verification for Force-Measuring Instruments, ASTM International", "url": "https://store.astm.org/e0074-18e01.html", "supports": "Backs the standard designation and its role in calibrating force-measuring instruments, including recalibration interval provisions." }, { "citation": "Morehouse Instrument Company, \"Understanding ISO 376\"", "url": "https://mhforce.com/understanding-iso-376/", "supports": "Backs the ISO 376 scope (force-proving instruments for verification of uniaxial testing machines) and its calibration and classification approach." } ], "guideUrl": "https://gaugelog.com/calibration/load-cell" }, { "id": "lux-meter", "name": "Lux Meter", "synonyms": [ "light meter", "illuminance meter", "luxmeter", "illumination meter", "photometric light meter" ], "category": "optical-light", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "intervalBasis": "No standard mandates a fixed interval; ISO/CIE 19476 and DIN 5032-7 define performance classes and test methods but leave recalibration frequency to the user. Most light meter suppliers recommend annual calibration as a starting point, with an allowable tolerance for change over the cycle; the interval is then shortened or extended from drift history, per the ILAC-G24 approach.", "intervalFactors": [ "Photodetector and V(lambda) filter aging, which causes gradual sensitivity drift that accumulates from year to year", "Exposure to UV, heat, and humidity, which accelerates degradation of the photometric correction filter", "Use for regulatory compliance measurements such as workplace or emergency lighting surveys, where results must be defensible", "Portable field use with frequent handling and transport versus stationary laboratory use", "As-found calibration history: units repeatedly found in tolerance can justify extending the interval, per ILAC-G24 methodology" ], "standards": [ { "designation": "ISO/CIE 19476:2014", "title": "Characterization of the performance of illuminance meters and luminance meters", "relevance": "Defines quality indices (such as spectral mismatch f1'), measurement procedures, and standard calibration conditions for illuminance meters" }, { "designation": "DIN 5032-7", "title": "Photometry - Part 7: Classification of illuminance meters and luminance meters", "relevance": "German standard defining accuracy classes and performance requirements for illuminance and luminance meters, commonly referenced on lux meter datasheets and calibration certificates" } ], "sources": [ { "citation": "ISO/CIE 19476:2014, Characterization of the performance of illuminance meters and luminance meters, ISO/CIE", "url": "https://www.iso.org/standard/65048.html", "supports": "Existence and scope of the performance characterization standard, quality indices, and standard calibration conditions" }, { "citation": "Why Calibrate Your Light Meter, International Light Technologies", "url": "https://internationallight.com/blog/why-calibrate-your-light-meter", "supports": "Backs the interval claim: most light meter suppliers start with a recommendation for an annual calibration and provide an allowable tolerance for change during the cycle, with the interval then adjusted from drift history" } ], "guideUrl": "https://gaugelog.com/calibration/lux-meter" }, { "id": "manometer", "name": "Manometer", "synonyms": [ "pressure gauge", "pressure gage", "U-tube manometer", "digital manometer", "pressure indicator" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Recalibrate immediately after overload/overpressure events, repair, or unusually heavy use rather than waiting for the calendar interval.", "intervalBasis": "No governing standard mandates a fixed interval; 12 months is the interval calibration labs commonly apply (Techmaster: 'Most quality systems calibrate a Pressure Gauge every 12 months'). ILAC-G24 / OIML D 10 describes how users should adjust that starting point from as-found drift data and risk.", "intervalFactors": [ "Exposure to overpressure spikes, pressure pulsation, or water hammer accelerates elastic element drift and justifies shorter intervals", "Continuous vibration (pumps, compressors) wears the movement of mechanical gauges and shortens the defensible interval", "Corrosive, clogging, or high-temperature process media degrade the sensing element faster than clean dry gas service", "Safety-critical or custody-relevant pressure readings warrant tighter intervals than indication-only gauges", "A stable as-found history within tolerance over several cycles supports extending beyond 12 months per ILAC-G24 methods" ], "standards": [ { "designation": "ASME B40.100", "title": "Pressure Gauges and Gauge Attachments", "relevance": "Defines accuracy grades, tolerances, and testing considerations for dial and digital pressure gauges" }, { "designation": "EURAMET Calibration Guide No. 17 (cg-17)", "title": "Guidelines on the Calibration of Electromechanical and Mechanical Manometers", "relevance": "The reference calibration procedure for electromechanical manometers and Bourdon tube gauges measuring absolute, gauge, and differential pressure" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval; no fixed interval is imposed" } ], "sources": [ { "citation": "Pressure Gauge Calibration: A Complete Guide, Techmaster Electronics", "url": "https://techmaster.us/pressure-gauge-calibration-a-complete-guide/", "supports": "The 12-month typical interval ('Most quality systems calibrate a Pressure Gauge every 12 months', sooner after repair, overload or heavy use), the 5-point rising/falling test procedure, reference standard accuracy of 0.1 percent or better, and as-found/as-left recording" }, { "citation": "EURAMET Calibration Guide No. 17, Guidelines on the Calibration of Electromechanical and Mechanical Manometers, EURAMET e.V.", "url": "https://www.euramet.org/publications-media-centre/calibration-guidelines", "supports": "The calibration procedure for electromechanical and mechanical manometers, including scope (absolute, gauge, differential pressure) and exercising the instrument before measurement" }, { "citation": "ILAC-G24 / OIML D 10:2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "The framing that no standard imposes a fixed interval and that intervals are adjusted from drift history and risk (interval basis and interval factors)" }, { "citation": "How often should instruments be calibrated?, Beamex blog", "url": "https://blog.beamex.com/how-often-to-calibrate-update", "supports": "Interval adjustment factors: criticality, drift/stability history, environmental conditions, and usage intensity; manufacturer recommendation as the starting point" } ], "guideUrl": "https://gaugelog.com/calibration/manometer" }, { "id": "micrometer", "name": "Micrometer", "synonyms": [ "outside micrometer", "external micrometer", "micrometer caliper", "digital micrometer", "mic" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Zero check at the closed position or against the setting standard before use; immediate recalibration after a drop, overload, or spindle damage", "intervalBasis": "Neither ISO 3611 nor ASME B89.1.13 sets a normative recalibration interval; both define design and error limits. The 12-month starting point is common calibration lab practice (Techmaster: most quality systems calibrate an outside micrometer every 12 months), refined by the user under the ILAC-G24 / OIML D 10 risk-based methodology.", "intervalFactors": [ "Measuring face wear: heavy use degrades anvil and spindle flatness and parallelism, which optical flat checks reveal", "Overtightening without using the ratchet or friction stop stresses the screw and shifts zero", "Exposure to coolant, grinding dust, and temperature swings at the point of use", "Handling risk from drops; a dropped micrometer frame can spring and should be recalibrated immediately", "Criticality of tolerances measured; micrometers guarding tight GD&T features warrant 3 to 6 month intervals", "As-found drift history; consistently in-tolerance results support extension toward 18 to 24 months" ], "standards": [ { "designation": "ISO 3611", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Design and metrological characteristics of micrometers for external measurements", "relevance": "International standard for external micrometers defining design and metrological characteristics used as calibration acceptance criteria" }, { "designation": "ASME B89.1.13-2013", "title": "Micrometers", "relevance": "US standard for outside, inside, and depth micrometers; the 2013 revision brought it into closer harmonization with ISO 3611" }, { "designation": "JIS B 7502", "title": "Micrometers", "relevance": "Japanese Industrial Standard specifying design and accuracy requirements for micrometers, widely cited on manufacturer inspection certificates" } ], "sources": [ { "citation": "Techmaster Electronics, \"Outside Micrometer Calibration\" (ISO/IEC 17025 accredited lab service page)", "url": "https://techmaster.us/outside-micrometer-calibration/", "supports": "The 12-month typical interval (most quality systems calibrate an outside micrometer every 12 months, sooner after repair, overload or heavy use), the references to ISO 3611, ASME B89.1.13 and DIN 863, and the procedure using gauge blocks, optical flat checks, repeatability testing, and MPE acceptance bands" }, { "citation": "ASME B89.1.13-2013, Micrometers, The American Society of Mechanical Engineers", "url": "https://webstore.ansi.org/standards/asme/asmeb89132013", "supports": "Standard designation, title, and its role as the US micrometer standard, revised in 2013 to bring closer harmonization with ISO 3611" }, { "citation": "Houston Precision Instruments, \"How Often Should Calipers and Micrometers Be Calibrated?\"", "url": "https://houstonprecision.com/how-often-should-calipers-and-micrometers-be-calibrated/", "supports": "Interval range and factors: 12 months as common standard, 3 to 6 months under heavy use or harsh conditions, and 18 to 24 months for lightly used tools with documented in-tolerance history" }, { "citation": "ILAC-G24 / OIML D 10:2022, Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories, ILAC and OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "The framing that recalibration intervals are determined by the user with risk-based methods (staircase, control chart, in-use time) rather than fixed by instrument standards, which underlies the interval basis statement" } ], "guideUrl": "https://gaugelog.com/calibration/micrometer" }, { "id": "moisture-meter", "name": "Moisture Meter", "synonyms": [ "wood moisture meter", "pin moisture meter", "pinless moisture meter", "damp meter", "moisture tester" ], "category": "chemical-analytical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Verify against the manufacturer check block, calibration check plate, or moisture content standard (MCS) before each survey or documented inspection; return the meter for full calibration if the check reads outside tolerance.", "intervalBasis": "ASTM D4444 defines the laboratory calibration method but not a calendar interval. Manufacturers rely primarily on user verification with check standards before use; Protimeter states that meters used under ISO-certified quality systems need independent calibration annually, and annual factory or laboratory calibration is the common recommendation for professional documented work.", "intervalFactors": [ "Use of readings in insurance claims, flooring warranty documentation, or certified inspections, which requires defensible calibration records", "Pin wear, corrosion, and contact resistance changes on pin-type meters", "Service in wet or contaminated environments such as flood restoration sites", "Frequency of drops and rough site handling of handheld units", "Results of routine checks against the manufacturer check block or moisture content standard; failures trigger immediate factory recalibration", "Battery condition and electronics drift affecting low-level resistance measurements" ], "standards": [ { "designation": "ASTM D4444", "title": "Standard Test Method for Laboratory Standardization and Calibration of Hand-Held Moisture Meters", "relevance": "Defines how hand-held wood moisture meters are standardized and calibrated in the laboratory against specimens whose moisture content is established by oven drying per ASTM D4442" }, { "designation": "ASTM D4442", "title": "Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials", "relevance": "Oven-drying reference method that provides the true moisture content values meters are calibrated against" } ], "sources": [ { "citation": "ASTM D4444-25, Standard Test Method for Laboratory Standardization and Calibration of Hand-Held Moisture Meters, ASTM International", "url": "https://www.en-standard.eu/astm-d4444-25-standard-test-method-for-laboratory-standardization-and-calibration-of-hand-held-moisture-meters/", "supports": "Existence and scope of the laboratory standardization and calibration method for hand-held moisture meters, with meters calibrated with respect to moisture content determined by ASTM D4442 oven drying" }, { "citation": "Digital Moisture Meter Calibration to Ensure Accurate Testing, Protimeter blog", "url": "https://blog.protimeter.com/blog/digital-moisture-meter-calibration-to-ensure-accurate-testing", "supports": "Interval claim: meters used to maintain ISO certification must be sent out for independent calibration annually, while routine user checks with built-in devices and moisture content standards cover day-to-day verification" }, { "citation": "Check Your Moisture Meter's Calibration in 3 Easy Steps, Delmhorst Instrument Co. blog", "url": "https://www.delmhorst.com/blog/moisture-meters-calibration", "supports": "Usage-based verification with built-in calibration checks, sensor blocks, and moisture content standards before use" } ], "guideUrl": "https://gaugelog.com/calibration/moisture-meter" }, { "id": "optical-comparator", "name": "Optical Comparator", "synonyms": [ "profile projector", "shadowgraph", "optical projector", "contour projector" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 36 }, "usageBasedInterval": "Recalibrate immediately after lamp/optics replacement, lens mount damage, relocation of the machine, or a failed interim check with a glass scale or certified gauge block.", "intervalBasis": "No ISO or ASME standard sets an interval; the interval is a user decision per ILAC-G24 methodology. Calibration providers commonly recommend about 6 months for high-use production inspection, 12 months for standard quality lab use, and up to 3 years for low-utilization toolroom installations.", "intervalFactors": [ "Utilization level: continuous production inspection versus occasional toolroom use shifts the interval strongly", "Stage wear and encoder drift from heavy X-Y travel under loaded fixtures", "Shop environment: temperature swings, vibration, and airborne coolant or dust degrade optics and stage accuracy", "Lens changes and handling: frequently swapped magnification lenses risk mount wear and magnification shift", "Criticality of screen-based measurements, for example first-article or final acceptance inspection of tight-tolerance profiles" ], "standards": [ { "designation": "JIS B 7184", "title": "Profile projectors (Japanese Industrial Standard)", "relevance": "The primary accuracy specification standard for profile projectors, defining magnification accuracy under contour and surface illumination, X/Y length accuracy, and axis squareness; no equivalent ISO or ASME standard exists." }, { "designation": "ILAC-G24 / OIML D 10", "title": "Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories", "relevance": "Provides the risk-based methodology for setting and reviewing the calibration interval, since no instrument standard mandates one." } ], "sources": [ { "citation": "AIMS Industrial Supplies, \"Profile Projector & Optical Comparator Guide\"", "url": "https://aimsindustrial.com.au/blogs/product-guides/profile-projector-optical-comparator-guide", "supports": "Backs the interval claim: 6 months for high-use production, 12 months for standard quality lab use, up to 3 years for low-utilization toolroom installations; also backs JIS B 7184:2021 as the accuracy reference and the verified characteristics." }, { "citation": "Cross Company, \"Optical Comparator Calibration Services | ISO 17025\"", "url": "https://www.crossco.com/services/calibration/inspection-equipment/optical-comparator-calibration/", "supports": "Confirms that ISO/IEC 17025 accredited laboratories offer optical comparator calibration with NIST-traceable standards, supporting the practice of periodic verification." }, { "citation": "Mitutoyo America Corporation, \"Profile Projectors - Accuracy and Calibration\" (educational resource EDU-15002)", "url": "https://www.mitutoyo.com/educational-resource/profile-projectors-accuracy-and-calibration/", "supports": "Backs the magnification verification method of projecting a master glass scale and measuring the image with a second calibrated glass reading scale, checked at multiple screen positions." } ], "guideUrl": "https://gaugelog.com/calibration/optical-comparator" }, { "id": "oscilloscope", "name": "Oscilloscope", "synonyms": [ "scope", "digital storage oscilloscope", "DSO", "mixed signal oscilloscope", "MSO", "o-scope" ], "category": "electrical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Run the instrument's built-in self-calibration or signal path compensation after significant ambient temperature changes and before critical measurements; recalibrate externally after repair or suspected overload of an input channel.", "intervalBasis": "There is no normative standard interval for oscilloscopes; the number comes from manufacturer recommendations. Tektronix states that calibration is recommended on a yearly basis, and Keysight guidance recommends annual calibration for digital and mixed signal scopes and every 1 to 2 years for analog scopes, with 12 months the most common Keysight factory recommendation and some instruments carrying 24 or 36 month recommended intervals.", "intervalFactors": [ "Measurement criticality: scopes used for pass/fail compliance or production test justify annual or shorter cycles, hobby or qualitative debugging use can tolerate longer", "Usage intensity and environment: portable use, temperature swings, and harsh industrial environments accelerate drift versus a bench in a controlled lab", "Bandwidth class: high-bandwidth models with fine timing specifications leave less margin for drift than basic 100 MHz bench scopes", "As-found calibration history: consistently in-tolerance results support extending toward the 2 year factory interval some models ship with", "Probe and input handling: frequent probe swapping, ESD exposure, and overdriven inputs increase the risk of channel gain errors between calibrations" ], "standards": [ { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Accredited oscilloscope calibration with documented traceability and uncertainty is performed under this standard" }, { "designation": "ILAC-G24 / OIML D 10", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Provides the risk-based methodology for setting and adjusting the oscilloscope's recalibration interval, since no instrument-specific normative interval exists" } ], "sources": [ { "citation": "Tektronix, FAQ \"How often should I calibrate the instrument?\" (Tektronix)", "url": "https://www.tek.com/en/support/faqs/how-often-should-i-calibrate-instrument", "supports": "The 12 month typical interval: Tektronix states calibration is recommended on a yearly basis" }, { "citation": "Keysight Technologies, \"Oscilloscope Calibration: Your Essential Guide\" (Used Keysight Equipment knowledge base)", "url": "https://www.keysight.com/used/us/en/knowledge/guides/oscilloscope-calibration-guide", "supports": "The interval range: annually for digital and mixed signal scopes, every 1 to 2 years for analog scopes depending on usage and environment, plus the parameters checked (vertical scaling, timebase, probe compensation, timing alignment)" }, { "citation": "Keysight Technologies, Technical Support Knowledge Center: \"What is the recommended calibration interval for my Keysight instrument?\" (Keysight)", "url": "https://docs.keysight.com/kkbopen/what-is-the-recommended-calibration-interval-for-my-keysight-instrument-678073287.html", "supports": "Factory interval guidance: 12 months is the most common recommended interval for Keysight instruments including oscilloscopes, with an increasing percentage of instruments at 24 or 36 months, which backs the extension toward 2 year cycles" }, { "citation": "Fluke Calibration, 9500B Oscilloscope Calibrator product page (Fluke)", "url": "https://www.fluke.com/en-us/product/calibration-tools/electrical-calibration/electrical-calibrators/9500b", "supports": "Reference equipment and capability claims: 6 GHz leveled sine, 70 ps pulse edges, five-channel active head output used to calibrate 4-channel scopes" } ], "guideUrl": "https://gaugelog.com/calibration/oscilloscope" }, { "id": "ph-meter", "name": "pH Meter", "synonyms": [ "pH tester", "pH electrode meter", "potentiometric pH meter", "pH probe", "electrometric pH analyzer" ], "category": "chemical-analytical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Standardize with at least two bracketing NIST-traceable buffers daily or before each measurement session; recalibrate immediately after electrode replacement or if slope/offset falls out of the acceptable range.", "intervalBasis": "ASTM D1293 requires standardizing the meter/electrode against at least two NIST-traceable buffers bracketing the sample pH, but treats this as routine standardization rather than a fixed calibration interval. Full instrument calibration/verification is a user decision, commonly 6 to 12 months, while buffer standardization is performed daily or per use.", "intervalFactors": [ "Frequency of buffer standardization already performed (daily standardization reduces reliance on long intervals)", "Electrode age and condition: aging glass and reference junctions drift and lose slope", "Sample matrix: dirty, proteinaceous, high-ionic-strength, or extreme-pH samples foul electrodes faster", "Temperature variation and whether automatic temperature compensation is used", "Criticality/regulatory status of the measurement (for example pharmaceutical water testing)", "As-found electrode slope and offset history" ], "standards": [ { "designation": "ASTM D1293", "title": "Standard Test Methods for pH of Water", "relevance": "Defines electrometric pH measurement with glass electrodes, standardization against at least two NIST-traceable buffers bracketing the sample, and Method A (precise lab) vs Method B (routine)." } ], "sources": [ { "citation": "ASTM D1293, Standard Test Methods for pH of Water, ASTM International", "url": "https://www.astm.org/Standards/D1293.htm", "supports": "Electrometric method, standardization against at least two NIST-traceable buffers bracketing the sample, and Method A/B distinction; basis that routine standardization is required while the full-calibration interval is a user decision." }, { "citation": "ASTM D1293 test standard overview, MaTestLabs", "url": "https://matestlabs.com/test-standards/astm-d1293/", "supports": "Two-buffer standardization and NIST-traceable buffer requirement; supports the daily-standardization / periodic-calibration interval framing." } ], "guideUrl": "https://gaugelog.com/calibration/ph-meter" }, { "id": "pipette", "name": "Pipette", "synonyms": [ "micropipette", "piston pipette", "air-displacement pipette", "POVA", "pipettor" ], "category": "mass-volume", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 12 }, "usageBasedInterval": "Many labs perform an intermediate user check (as-found volume verification at nominal volume) monthly or quarterly between full calibrations, and after any drop, repair, or piston/seal service.", "intervalBasis": "ISO 8655-1 does not set a fixed calibration interval; it places responsibility on the user to define a routine testing schedule based on risk and use. Calibration labs and manufacturers commonly recommend 6 to 12 months for general use, tightening to 3 to 6 months for daily high-throughput or regulated (GLP/GMP) work.", "intervalFactors": [ "Usage intensity: pipettes used many times per day in high-throughput labs need shorter intervals than occasionally used units", "Criticality of the measurement: clinical, pharmaceutical, and forensic dosing justify tighter intervals than non-critical prep work", "Liquid class handled: viscous, volatile, or corrosive liquids accelerate seal wear and drift", "As-found history: a unit that repeatedly fails or drifts near tolerance limits warrants more frequent calibration", "Handling and mechanical risk: units subject to drops, autoclaving, or heavy multichannel use degrade faster", "Regulatory regime: GLP/GMP and ISO 17025 environments often mandate documented shorter intervals" ], "standards": [ { "designation": "ISO 8655-1:2022", "title": "Piston-operated volumetric apparatus - Part 1: Terminology, general requirements and user recommendations", "relevance": "Defines general metrological requirements and places responsibility on the user to establish routine testing and calibration schedules." }, { "designation": "ISO 8655-2:2022", "title": "Piston-operated volumetric apparatus - Part 2: Pipettes", "relevance": "Specifies maximum permissible errors (systematic and random) and metrological requirements for pipettes." }, { "designation": "ISO 8655-6:2022", "title": "Piston-operated volumetric apparatus - Part 6: Gravimetric reference measurement procedure for the determination of volume", "relevance": "Defines the gravimetric reference method used to calibrate pipettes, including test volumes, replicate counts, and balance requirements." } ], "sources": [ { "citation": "ISO 8655-1:2022, Piston-operated volumetric apparatus - Part 1: Terminology, general requirements and user recommendations, International Organization for Standardization", "url": "https://www.iso.org/obp/ui/en/#!iso:std:68796:en", "supports": "General requirement that users define their own routine testing/calibration schedule; ISO 8655 does not mandate a fixed interval, so the 6-12 month typical interval derives from user risk assessment and lab practice." }, { "citation": "ISO 8655-6:2022, Piston-operated volumetric apparatus - Part 6: Gravimetric reference measurement procedure for the determination of volume, International Organization for Standardization", "url": "https://www.iso.org/standard/75211.html", "supports": "Gravimetric procedure, test volumes (100/50/10 percent), minimum 10 replicates, and balance requirements in the procedure outline." }, { "citation": "Labtain, How Often Should Pipettes Be Calibrated? ISO 8655 Explained Clearly and Practically", "url": "https://www.labtain.com/blog/75267-how-often-should-pipettes-be-calibrated-iso-8655-explained-clearly-and-practically", "supports": "Common 6-12 month calibration interval for standard use and 3-6 months for daily high-throughput, clinical, or production environments; confirms ISO 8655 does not mandate a fixed interval and expects a risk-based lab schedule." } ], "guideUrl": "https://gaugelog.com/calibration/pipette" }, { "id": "plain-plug-gauge", "name": "Plug Gauge", "synonyms": [ "plug gage", "plain plug gauge", "go/no-go plug gauge", "cylindrical plug gauge", "pin gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "High-use gauges warrant quarterly or even monthly verification; recalibrate immediately after drops, overload, or visible damage, and test new hardened gauges after the first year to evaluate hardened steel growth.", "intervalBasis": "No standard mandates a recalibration interval for hardened fixed-limit gauges; gauge makers state that frequency must be set per gauge from usage and wear history. Calibration providers such as Techmaster commonly recommend every 6 to 12 months as a starting point, with quarterly or even monthly checks for high-use environments.", "intervalFactors": [ "Number of parts gauged per day, since every insertion of the go member abrades its surface", "Hardness and abrasiveness of the workpiece material (soft plastic wears the gauge far more slowly than hardened steel or abrasive castings)", "Criticality of the toleranced holes, because a worn undersized go member produces false-pass results", "As-found drift and wear trend documented on previous calibration certificates", "Cleanliness of the gauging environment, since grit and chips accelerate wear", "Handling risk such as drops and corrosion from skin contact without preservation oil" ], "standards": [ { "designation": "ISO 1938-1", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size", "relevance": "Defines plain limit gauge types including full form cylindrical plug gauges, their design and metrological characteristics, and the new and wear limit maximum permissible limits (MPLs) used as calibration acceptance criteria; second edition published 2026 replacing ISO 1938-1:2015." }, { "designation": "ASME B89.1.5", "title": "Measurement of Plain External Diameters for use as Master Discs or Cylindrical Plug Gages", "relevance": "Establishes uniform practices and tolerances for measuring plain external diameters of cylindrical plug gauges; 1998 edition reaffirmed 2024." } ], "sources": [ { "citation": "Techmaster Electronics, \"Plug Gage Calibration That Stands Up to Audits\" (calibration provider guide)", "url": "https://techmaster.us/plug-gage-calibration/", "supports": "Interval claim: recommends calibration every 6 to 12 months as the most common interval, with quarterly or even monthly checks for high-use environments and recalibration after any damage; also supports the as-found/as-left procedure flow." }, { "citation": "Ring & Plug Thread Gages (Westport Gage), \"Calibration Frequency for Hardened Tooling\" technical note", "url": "https://www.ring-plug-thread-gages.com/ti-Calibration-Frequency.htm", "supports": "Interval basis honesty: states no specified recalibration frequency exists for hard gauges or GO/NOGO gauges, recommends testing after the first year for hardened steel growth, and bases frequency on usage volume, workpiece material, and environment." }, { "citation": "ISO 1938-1:2026, Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size, International Organization for Standardization", "url": "https://www.iso.org/standard/87858.html", "supports": "Standard confirmation: gauge types, design and metrological characteristics, and new/wear limit MPLs used as acceptance criteria." }, { "citation": "ASME B89.1.5-1998 (R2024), Measurement of Plain External Diameters for use as Master Discs or Cylindrical Plug Gages, The American Society of Mechanical Engineers", "url": "https://webstore.ansi.org/standards/asme/asmeb891998r2024", "supports": "Standard confirmation: measurement methods and tolerances for plain cylindrical plug gauge diameters." } ], "guideUrl": "https://gaugelog.com/calibration/plain-plug-gauge" }, { "id": "pressure-gauge", "name": "Pressure Gauge", "synonyms": [ "pressure gage", "dial pressure gauge", "analog pressure gauge", "Bourdon tube gauge", "test gauge" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Recalibrate immediately if the pointer does not return to zero, after any overpressure event, and after repair; many sites also perform an in-place zero check at routine inspections.", "intervalBasis": "No standard mandates a fixed interval; the interval is a user decision per ILAC-G24/OIML D 10 methodology. Gauge manufacturer Ashcroft states the typically suggested time to check instrument calibration is once every 12 months for stable industrial service, shortened for harsh conditions such as vibration, pulsation, or rapid cycling.", "intervalFactors": [ "Vibration and pressure pulsation cause mechanical wear of the Bourdon tube movement and accelerate drift", "Overpressure events or water hammer can permanently deform the elastic element and require immediate recalibration", "A pointer that does not return to zero (or sits outside the zero box) is a trigger for immediate recalibration", "Higher accuracy grades (test gauges per ASME B40.100 Grade 2A/3A or EN 837-1 class 0.6 and better) warrant tighter, more frequent checking than process-grade gauges", "Criticality of the reading, for example safety-related or custody transfer measurements versus simple local indication", "Corrosive media or extreme process and ambient temperatures degrade the element and movement faster" ], "standards": [ { "designation": "ASME B40.100-2022", "title": "Pressure Gauges and Gauge Attachments", "relevance": "US standard covering dial-type elastic element and digital pressure gauges, their accuracy grades, and gauge attachments" }, { "designation": "EN 837-1", "title": "Pressure gauges - Part 1: Bourdon tube pressure gauges - Dimensions, metrology, requirements and testing", "relevance": "European standard defining accuracy classes, metrological requirements, and test methods for Bourdon tube pressure and vacuum gauges" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and adjusting the recalibration interval, since no gauge standard fixes one" } ], "sources": [ { "citation": "Ashcroft blog, \"How Often Should I Check the Calibration of My Pressure Gauge?\"", "url": "https://blog.ashcroft.com/pressure-gauge-calibration-interval", "supports": "The interval: typically suggested calibration check is once every 12 months, shortened for harsh conditions (vibration, pulsation, rapid cycling), plus the immediate-recalibration trigger when the pointer is off zero" }, { "citation": "Beamex white paper, \"How to calibrate pressure gauges - 20 things you should consider\"", "url": "https://resources.beamex.com/pressure-gauge-calibration", "supports": "Procedure details: exercising the gauge, number of calibration points, hysteresis (rising/falling), tapping, documentation, and traceability" }, { "citation": "ASME B40.100-2022, Pressure Gauges and Gauge Attachments, American Society of Mechanical Engineers", "url": "https://www.asme.org/codes-standards/find-codes-standards/b40-100-pressure-gauges-gauge-attachments", "supports": "Existence and scope of the US gauge standard consolidating dial and digital pressure gauge requirements" }, { "citation": "BS EN 837-1:1998, Pressure gauges - Bourdon tube pressure gauges - Dimensions, metrology, requirements and testing, CEN/BSI", "url": "https://www.en-standard.eu/bs-en-837-1-1998-pressure-gauges-bourdon-tube-pressure-gauges-dimensions-metrology-requirements-and-testing/", "supports": "Scope and metrological requirements for Bourdon tube pressure and vacuum gauges up to 1600 bar" } ], "guideUrl": "https://gaugelog.com/calibration/pressure-gauge" }, { "id": "pressure-transmitter", "name": "Pressure Transmitter", "synonyms": [ "pressure transducer", "pressure sensor", "DP transmitter", "differential pressure transmitter", "smart transmitter" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 60 }, "usageBasedInterval": "Recalibrate after process excursions such as overpressure or diaphragm seal damage, after loop repairs, and perform a zero trim whenever mounting position or static line pressure conditions change.", "intervalBasis": "There is no normative interval; Emerson's technical note on calculating transmitter calibration intervals reports that US 40 CFR Part 98 greenhouse gas rules suggest annual recalibration of DP transmitters in flow service, and shows how to compute a device-specific interval from required performance, total probable error, and the stability specification, yielding 20 to 104 months depending on transmitter performance class.", "intervalFactors": [ "Transmitter performance class and published stability specification (for example 5-, 10-, or 15-year stability ratings) largely set the achievable interval", "Required installed performance: safety and custody applications at 0.5 percent of span need much shorter intervals than 2 percent monitoring points", "Ambient temperature swings and high static line pressure on DP transmitters add installation error and shrink the interval margin", "Regulatory obligations, for example annual recalibration suggested for DP flow transmitters under 40 CFR Part 98 reporting", "As-found history from documenting calibrators: repeated in-tolerance results support extending the interval, drift near limits supports shortening it", "Process events such as overpressure, slugging, or diaphragm seal damage warrant immediate recalibration" ], "standards": [ { "designation": "IEC 60770-1", "title": "Transmitters for use in industrial-process control systems - Part 1: Methods for performance evaluation", "relevance": "Defines uniform test methods for evaluating transmitter performance, used to establish the specifications interval calculations rely on" }, { "designation": "IEC 60770-2", "title": "Transmitters for use in industrial-process control systems - Part 2: Methods for inspection and routine testing", "relevance": "Methods for inspection and routine testing of transmitters, for example at acceptance or after repair" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Recognized methodology (drift data, control charts, in-use time) for setting and adjusting transmitter calibration intervals" } ], "sources": [ { "citation": "Emerson Technical Note 00840-1900-4801 Rev AA, \"How to Calculate Pressure Transmitter Calibration Intervals\" (March 2021)", "url": "https://www.emerson.com/documents/automation/technical-note-how-to-calculate-pressure-transmitter-calibration-intervals-en-7432098.pdf", "supports": "The interval claims: 40 CFR Part 98 suggests annual recalibration of DP transmitters in flow applications; manufacturers generally do not publish intervals; the five-step total-probable-error and stability method; calculated intervals of 20 to 104 months by performance class" }, { "citation": "IEC 60770-1, Transmitters for use in industrial-process control systems - Part 1: Methods for performance evaluation, International Electrotechnical Commission", "url": "https://www.document-center.com/standards/show/IEC-60770-1", "supports": "Standardized performance evaluation methods for process transmitters" }, { "citation": "ILAC-G24 / OIML D 10:2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Risk-based methodology (automatic adjustment, control charts, in-use time) behind treating the transmitter interval as a user decision refined from drift data" } ], "guideUrl": "https://gaugelog.com/calibration/pressure-transmitter" }, { "id": "radius-gauge", "name": "Radius Gauge", "synonyms": [ "radius gage", "fillet gauge", "fillet gage", "radius gauge set" ], "category": "dimensional", "typicalIntervalMonths": 24, "intervalRangeMonths": { "min": 12, "max": 60 }, "usageBasedInterval": "Inspect blades for nicks, burrs, and edge wear before use; re-verify any blade that has been dropped, filed against a part, or shows visible edge damage.", "intervalBasis": "No standard or manufacturer sets a normative interval. Ape Software's published radius gage calibration procedure treats the gauge as an inherently stable device that does not require routine recalibration unless the user requests it; in practice quality systems assign a 12 to 60 month verification cycle using the general recalibration-interval methodology of ILAC-G24 / OIML D 10, adjusted for wear observed at each check.", "intervalFactors": [ "Frequency of contact use against hard or abrasive workpieces, which rounds and wears the template edge", "Whether the gauge is used for acceptance decisions on toleranced radii or only for rough shop reference", "Nicks and burrs from contact with machined edges, which create false light gaps", "Corrosion risk from handling thin unprotected steel blades without oiling", "As-found condition history from previous verifications, since undamaged blades are dimensionally stable" ], "standards": [ { "designation": "OIML D 10 / ILAC-G24", "title": "Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories", "relevance": "Provides the interval-setting methodology used for radius gauges, since no instrument-specific standard prescribes an interval; 2022 edition." } ], "sources": [ { "citation": "Ape Software, \"Free Radius Gage Calibration Procedure\" (published calibration procedure)", "url": "https://www.apesoftware.com/help/calibration-procedures/radius-gage", "supports": "Interval claim: states the radius gauge is considered an inherently stable device that will not require recalibration unless specially requested; also supports the optical comparator method, comparator accuracy requirement, and the size-banded acceptance tolerances." }, { "citation": "ILAC-G24 / OIML D 10 Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment used in testing laboratories, ILAC and OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Interval basis: documents that no standard imposes a fixed interval and describes the methods (automatic adjustment, control chart, in-use time, in-service checking) used to set and adjust intervals for equipment like radius gauges." }, { "citation": "ACS Calibration, \"Radius Gage Calibration\" accredited service description", "url": "https://acscalibration.com/calibration-services/radius-gage-calibration/", "supports": "Confirms that ISO/IEC 17025 accredited laboratories offer radius gauge calibration as routine service, supporting the practice of periodic verification." } ], "guideUrl": "https://gaugelog.com/calibration/radius-gauge" }, { "id": "refractometer", "name": "Refractometer", "synonyms": [ "Brix refractometer", "digital refractometer", "Abbe refractometer", "refractive index meter", "Brix meter" ], "category": "chemical-analytical", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Verify the zero point with distilled water at the start of each measurement session and periodically during extended use; verify against a certified sucrose standard regularly for critical quantitative work.", "intervalBasis": "There is no instrument-specific normative recalibration interval; frequency is a user/lab decision. Manufacturers instruct users to perform a distilled-water zero calibration daily or before each measurement session, periodic verification against certified sucrose or refractive-index standards is common practice, and calibration providers recommend a certified traceable calibration at minimum yearly.", "intervalFactors": [ "Accuracy requirement: quantitative concentration measurement needs tighter verification than a pass/fail field check", "Temperature control: instruments without automatic temperature compensation drift with ambient temperature and need more frequent zeroing", "Sample aggressiveness: acidic, sugary, or staining samples that leave residue on the prism shift readings between cleanings", "Usage frequency and environment (production floor vs controlled lab)", "As-found drift history against the sucrose standards", "Handling risk to the prism surface (scratching, film buildup)" ], "standards": [ { "designation": "ICUMSA SPS-3 (2000)", "title": "ICUMSA Specification and Standard SPS-3: Refractometry and Tables - Official", "relevance": "Defines the relationship between refractive index and sucrose concentration and the reference tables used to verify Brix refractometers." } ], "sources": [ { "citation": "Cargille Labs, About Brix Liquids (Brix/refractive-index reference standards)", "url": "https://www.cargille.com/about-brix-liquids/", "supports": "Definition of Brix from refractive index based on the ICUMSA tables, water zero point, and use of certified Brix/refractive-index standards." }, { "citation": "Refractometer Shop, Brix Sucrose Solution for refractometer calibration", "url": "https://refractometershop.com/products/brix-sucrose-solution", "supports": "Certified sucrose calibration solutions supplied with UKAS ISO/IEC 17025 calibration certificates and traceability to ICUMSA and NIST." }, { "citation": "Hanna Instruments, Digital Sucrose Refractometer instruction manual", "url": "https://www.documentation.hannainst.com/manuals/preview/1853", "supports": "Manufacturer instruction to perform zero calibration with distilled or deionized water daily, before measurements are made, and after battery changes or environmental changes." }, { "citation": "MISCO, Importance of Refractometer Calibration", "url": "https://www.misco.com/importance-of-refractometer-calibration/", "supports": "Recommendation that a certified traceable calibration be performed at minimum on a yearly basis, establishing the baseline for subsequent field checks; supports the 12 month typical interval." } ], "guideUrl": "https://gaugelog.com/calibration/refractometer" }, { "id": "rtd", "name": "Resistance Temperature Detector (RTD)", "synonyms": [ "resistance thermometer", "Pt100", "Pt1000", "platinum resistance thermometer", "PRT" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "A single-point ice point (0 C) resistance check is a common quick verification between full calibrations and after suspected mechanical shock.", "intervalBasis": "No normative interval exists for industrial RTDs; annual or semi-annual calibration is what industry practice and internal quality systems commonly dictate ('Industry standards and internal quality systems often dictate annual or semi-annual calibration for an rtd pt100', DXM guidance). Extension beyond 12 months should be justified by stable as-found history per ILAC-G24 methods.", "intervalFactors": [ "Mechanical shock and vibration strain the platinum element and shift resistance, shortening the interval in pump, compressor, or mobile installations", "Repeated thermal cycling near the sensor's range limits accelerates drift compared with steady mid-range service", "Moisture ingress past the sheath seal degrades insulation resistance and causes reading errors, a known failure mode checked at calibration", "Tight tolerance classes (IEC 60751 Class AA or A) leave less drift margin than Class B, so high-accuracy applications need more frequent verification", "Stable as-found results at the ice point across cycles support extending the interval toward 24 months" ], "standards": [ { "designation": "IEC 60751", "title": "Industrial platinum resistance thermometers and platinum temperature sensors", "relevance": "Defines the Pt100 resistance-temperature relationship (3850 ppm/K) and tolerance Classes AA, A, and B used as acceptance criteria" }, { "designation": "ASTM E1137/E1137M", "title": "Standard Specification for Industrial Platinum Resistance Thermometers", "relevance": "The North American specification for industrial platinum RTDs, closely aligned with IEC 60751 and based on ITS-90" }, { "designation": "ASTM E644", "title": "Standard Test Methods for Testing Industrial Resistance Thermometers", "relevance": "Test methods for calibration, insulation resistance, self-heating, immersion error, stability, and hysteresis of industrial resistance thermometers" } ], "sources": [ { "citation": "RTD PT100 Calibration: Boost Accuracy and Performance, DXM (dxmht.com)", "url": "https://www.dxmht.com/article/how-to-calibrate-rtd-pt100.html", "supports": "The interval claim: 'Industry standards and internal quality systems often dictate annual or semi-annual calibration for an rtd pt100', plus event-based triggers (mechanical shock, extreme temperatures, questionable readings)" }, { "citation": "Resistance Thermometer Basics + RTD Calibration in 5 Steps, Fluke Calibration", "url": "https://www.fluke.com/en-us/learn/blog/calibration/5-steps-calibrate-rtd", "supports": "The comparison/characterization procedure: co-locating DUTs with the reference probe in the temperature source, measuring resistance, and fitting calibration coefficients" }, { "citation": "ASTM E644, Standard Test Methods for Testing Industrial Resistance Thermometers, ASTM International", "url": "https://www.astm.org/Standards/E644.htm", "supports": "Test methods for calibration, insulation resistance, self-heating, stability, and hysteresis referenced in the procedure outline" }, { "citation": "RTD Accuracy Classes - Class AA, A, B, Pt100 and Pt1000, Thermometrics", "url": "https://thermometricscorp.com/rtd-accuracy-classes.html", "supports": "IEC 60751 tolerance classes (AA, A, B) and their formulas used as acceptance criteria, and the tightest tolerance being at 0 C" } ], "guideUrl": "https://gaugelog.com/calibration/rtd" }, { "id": "ring-gauge", "name": "Ring Gauge", "synonyms": [ "ring gage", "master ring", "setting ring", "plain ring gauge", "go/no-go ring gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Recalibrate immediately after any impact, drop, suspected damage, or exposure to extreme conditions, and verify before first use after procurement.", "intervalBasis": "ASME B89.1.6 defines how to measure master rings but does not mandate an interval. Materials testing and calibration provider Infinita Lab recommends calibrating ring gauges before first use and every 6-12 months for production gauges depending on frequency of use, with immediate recalibration after impact or suspected damage; the final interval is a risk-based user decision per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Frequency of use on the production line versus occasional use as a lab master for setting bore and air gauges", "Wear of the bore from repeated engagement with parts or gauge contacts, which shows up as size growth and form error (taper, lobing, bell-mouth)", "Tolerance class of the ring: tighter classes (X, XX) have less allowance between as-found wear and the acceptance limit", "Handling events: drops and impacts can distort a ring even without visible damage, so incident-triggered recalibration matters more than calendar time", "Criticality of downstream measurements, since a drifted master ring offsets every instrument that is set with it" ], "standards": [ { "designation": "ASME B89.1.6", "title": "Measurement of Qualified Plain Internal Diameters for Use as Master Rings and Ring Gages", "relevance": "Establishes uniform practices for measuring master rings and ring gauges, including geometric requirements, comparison equipment characteristics, environmental conditions, and accuracy assurance." }, { "designation": "ISO 1938-1:2015", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size", "relevance": "Defines plain limit gauges including go/no-go ring gauges, with design characteristics and new/wear maximum permissible limits applied at recalibration." } ], "sources": [ { "citation": "Infinita Lab, \"Ring Gauge Maintenance & Calibration\", materials testing laboratory technical article", "url": "https://infinitalab.com/blog/ring-gauge-maintenance-calibration/", "supports": "Backs the interval claim (calibrate before first use, every 6-12 months for production gauges based on frequency of use, and after any impact, suspected damage, or exposure to extreme conditions) and the procedure: measurement at multiple axial planes and angular positions to detect lobing, taper, and barrel shape, using air gauges, bore gauges with electronic amplifiers, or CMM with ruby probe, with NIST-traceable documentation." }, { "citation": "ASME B89.1.6, Measurement of Qualified Plain Internal Diameters for Use as Master Rings and Ring Gages, The American Society of Mechanical Engineers", "url": "https://standards.globalspec.com/std/933383/ASME%20B89.1.6", "supports": "Backs the standards listing and measurement methodology: uniform practices for measuring master rings including geometric requirements, comparison equipment, and environmental conditions." }, { "citation": "ISO 1938-1:2015, Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size, International Organization for Standardization", "url": "https://www.iso.org/standard/41132.html", "supports": "Backs the standards listing: limit gauge definitions and new/wear maximum permissible limits used as acceptance criteria for go/no-go ring gauges." } ], "guideUrl": "https://gaugelog.com/calibration/ring-gauge" }, { "id": "snap-gauge", "name": "Snap Gauge", "synonyms": [ "snap gage", "gap gauge", "adjustable snap gauge", "go/no-go snap gauge", "indicating snap gage" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Adjustable and indicating snap gauges are mastered (zeroed) against gauge block stacks or a master disc at each setup or shift; anvil wear and parallelism should be checked regularly in production, with the periodic full calibration verifying the gauge against its tolerance and wear limits.", "intervalBasis": "No product standard sets a normative interval. Calibration practice guides state that snap gauges are typically calibrated at least annually, with more frequent checks in demanding production environments; the interval is a user decision driven by usage intensity and wear history.", "intervalFactors": [ "Parts gauged per day and abrasiveness of the workpiece surface sliding past the anvils", "Anvil material, since tungsten carbide anvils resist wear far longer than hardened steel", "Repeated gauging of narrow parts on broad anvils, which wears local grooves that mastering at one point may not detect", "Drop and impact risk to the C-frame, which can spring the frame and shift both limits at once", "Criticality of the external diameters inspected and the cost of a false accept", "As-found wear and parallelism trend from previous calibrations" ], "standards": [ { "designation": "ASME B47.1", "title": "Gage Blanks", "relevance": "Covers standard designs for adjustable snap gauge blanks up to 12 inches; 2007 edition reaffirmed 2022." }, { "designation": "ISO 1938-1", "title": "Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size", "relevance": "Defines plain limit gauges of linear size including gap gauges for external dimensions, with design characteristics and new/wear limit MPLs; the 2026 second edition explicitly adds the gap gauge." } ], "sources": [ { "citation": "Shyam Research Academy, \"Snap Gauge Calibration Calculate / IS 3455\" technical article", "url": "https://shyamresearch.com/snap-gauge-calibration-calculate-is-3455/", "supports": "Interval claim: states snap gauges are typically calibrated at least annually, with more frequent checks in demanding environments; also supports environmental conditioning and wear-limit acceptance criteria." }, { "citation": "The Gage Site, Metrology Toolbox, \"Using Adjustable Snap Gages\" (Section M, hand tools guide)", "url": "https://www.gagesite.com/documents/Metrology%20Toolbox/HandTools.PDF", "supports": "Procedure details: mastering with gauge block stacks or master discs, checking anvil parallelism with a precision wire or ball at four anvil edges, regular anvil wear inspection, and locking/re-check practice for adjustable snap gauges." }, { "citation": "Applied Technical Services (ATS), \"Snap Gauge Calibration\" service description", "url": "https://atslab.com/calibration/mechanical-equipment/snap-gauge-calibration/", "supports": "Procedure details: 24-hour thermal conditioning at 68 degrees F plus or minus 2, damage inspection, and comparison against NIST-traceable standards on a Pratt & Whitney Labmaster Universal." }, { "citation": "ASME B47.1-2007 (R2022), Gage Blanks, The American Society of Mechanical Engineers", "url": "https://webstore.ansi.org/standards/asme/asmeb472007r2022", "supports": "Standard confirmation: covers adjustable snap gauge blanks up to 12 inches." } ], "guideUrl": "https://gaugelog.com/calibration/snap-gauge" }, { "id": "sound-level-meter", "name": "Sound Level Meter", "synonyms": [ "SLM", "noise meter", "decibel meter", "noise level meter", "sound meter" ], "category": "acoustic-vibration", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 12, "max": 24 }, "usageBasedInterval": "Field check with an IEC 60942 acoustic calibrator (typically 94 dB at 1 kHz) before and after each measurement session; investigate and recalibrate if the levels disagree beyond the allowed tolerance.", "intervalBasis": "IEC 61672-3 defines the periodic test procedure but not the interval; the interval is set by the regulations being followed. Guidance for UK and EU noise-at-work regulations calls for laboratory verification at least every two years, while annual calibration is commonly recommended for heavy use, legal work, or harsh environments.", "intervalFactors": [ "Applicable regulation: some noise measurement regulations require verification every year, others every two years", "Use of results for legal or enforcement purposes, which demands current accredited periodic test evidence", "Microphone exposure to humidity, dust, wind, and temperature extremes in outdoor environmental monitoring", "Intensity of field use and transport, which increases risk of microphone and preamplifier damage", "Discrepancies observed during before and after field checks with the acoustic calibrator, which indicate drift between laboratory tests" ], "standards": [ { "designation": "IEC 61672-1", "title": "Electroacoustics - Sound level meters - Part 1: Specifications", "relevance": "Defines class 1 and class 2 performance requirements that the meter must meet" }, { "designation": "IEC 61672-3", "title": "Electroacoustics - Sound level meters - Part 3: Periodic tests", "relevance": "Defines the periodic test procedure used by laboratories to verify continued conformance to IEC 61672-1 for a limited period" }, { "designation": "IEC 60942", "title": "Electroacoustics - Sound calibrators", "relevance": "Specifies requirements for the acoustic calibrators used for field checks and for the acoustical test in periodic testing" } ], "sources": [ { "citation": "IEC 61672-3:2013, Electroacoustics - Sound level meters - Part 3: Periodic tests, IEC", "url": "https://webstore.iec.ch/en/publication/5710", "supports": "Existence and scope of the periodic test procedure that verifies conformance to IEC 61672-1 for a limited period; basis for the procedure outline" }, { "citation": "Sound Level Meter Calibration and Verification (FAQ), NoiseMeters Inc.", "url": "https://www.noisemeters.com/help/faq/calibration/", "supports": "Interval claim: the applicable noise regulations set the period between laboratory calibrations, some requiring 1 year and some 2 years (UK and EU noise-at-work at least every two years), annual calibration recommended for legal or heavy use, plus the practice of field checks with a sound calibrator before and after measurements" }, { "citation": "IEC 61672 - A Standard for Sound Level Meters Explained, Cirrus Research plc", "url": "https://cirrusresearch.com/iec-61672-a-standard-for-sound-level-meters-in-three-parts/", "supports": "The three-part structure of IEC 61672 and the role of Part 1 specifications and Part 3 periodic testing" } ], "guideUrl": "https://gaugelog.com/calibration/sound-level-meter" }, { "id": "steel-rule", "name": "Steel Rule", "synonyms": [ "machinist rule", "steel ruler", "engineer's rule", "rigid steel scale", "metal rule" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "intervalBasis": "The ITTC recommended procedure 7.6-02-01 (Calibration of Steel Rulers, based on Chinese verification regulation JJG 1-1999) states that the calibration period of a steel ruler in service can be determined from its service condition and is usually one year. Calibration provider Techmaster likewise reports that most quality systems calibrate a steel ruler every 12 months, sooner after repair, overload, or heavy use; shorter or longer intervals are risk-based user adjustments.", "intervalFactors": [ "Heavy shop-floor use as a marking and scribing tool, which wears the end edge that graduations are referenced from", "Mechanical events such as drops, bending beyond elastic limit, or use as a scraper or pry, which damage edge linearity", "Corrosive or dirty environments (coolant, cutting fluids) that degrade the engraved lines and edges", "Whether the rule is used for toleranced product measurements or only for rough layout, which changes measurement criticality", "As-found history: rules that repeatedly pass with large margin can justify extending toward 24 months under ILAC-G24 methods" ], "standards": [ { "designation": "JIS B 7516:2005", "title": "Metal rules", "relevance": "Japanese product standard specifying graduation tolerances for metal rules by length, widely used internationally as the acceptance specification when calibrating steel rules." }, { "designation": "BS 4372:1968", "title": "Specification for engineers' steel measuring rules", "relevance": "British product standard for engineers' steel rules up to 1 meter, defining requirements the rule is verified against." } ], "sources": [ { "citation": "ITTC Recommended Procedures and Guidelines 7.6-02-01, Sample Work Instructions: Calibration of Steel Rulers, International Towing Tank Conference, 2002 (based on JJG 1-1999)", "url": "https://ittc.info/media/4228/76-02-01.pdf", "supports": "Backs the interval claim (calibration period of a steel ruler in service is usually one year, determined from service condition) and the full procedure: exterior, flatness, edge linearity/verticality, line width, indication error against a third-grade standard metal line ruler, temperature conditions, and acceptance tables." }, { "citation": "Techmaster Electronics, \"Steel Ruler Calibration\", accredited calibration service guide", "url": "https://techmaster.us/steel-ruler-calibration/", "supports": "Backs the interval claim that most quality systems calibrate a steel ruler every 12 months and sooner after repair, overload, or heavy use, and the ISO/IEC 17025 / NIST-traceable framing of the calibration." }, { "citation": "JIS B 7516:2005, Metal rules, Japanese Standards Association", "url": "https://webstore.ansi.org/standards/jis/jis75162005", "supports": "Backs the standards listing: JIS B 7516 exists as the product standard specifying graduation tolerances for metal rules used as calibration acceptance criteria." }, { "citation": "BS 4372:1968, Specification for engineers' steel measuring rules, British Standards Institution", "url": "https://knowledge.bsigroup.com/products/specification-for-engineers-steel-measuring-rules", "supports": "Backs the standards listing: BS 4372 exists and covers engineers' steel measuring rules up to 1 meter for engineering use." } ], "guideUrl": "https://gaugelog.com/calibration/steel-rule" }, { "id": "stopwatch", "name": "Stopwatch", "synonyms": [ "timer", "digital stopwatch", "stop watch", "electronic timer", "lab timer" ], "category": "time-frequency", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 12, "max": 24 }, "usageBasedInterval": "Verify against a known time reference (for example a traceable time-of-day source) before critical timed procedures; recalibrate after battery replacement on quartz units if accuracy is questioned.", "intervalBasis": "No standard mandates a fixed stopwatch interval; NIST SP 960-12 describes the calibration methods and traceability but leaves interval selection to the user based on tolerance and criticality. Annual calibration is the most common requirement for general test equipment, with looser intervals for non-critical use.", "intervalFactors": [ "Required tolerance: a tight test tolerance (for example seconds per hour) demands tighter interval control", "Criticality of the timed measurement to product or safety outcomes", "Quartz aging and temperature exposure, which shift the oscillator rate over time", "As-found drift history relative to the applied tolerance", "Whether the device is used as the sole timing reference or cross-checked against another clock" ], "standards": [ { "designation": "NIST SP 960-12", "title": "NIST Recommended Practice Guide: Stopwatch and Timer Calibrations (2009 edition)", "relevance": "Describes stopwatch/timer types, tolerances, calibration methods (direct comparison, totalize, time base), and measurement uncertainties, and traceability to national time/frequency standards." } ], "sources": [ { "citation": "NIST Special Publication 960-12, Stopwatch and Timer Calibrations (2009 edition), Gust, Graham, Lombardi, NIST", "url": "https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication960-12e2.pdf", "supports": "Stopwatch/timer types, tolerances, calibration methods (direct comparison, totalize, time base), test-interval accumulation, uncertainties, and traceability." }, { "citation": "Fluke Corporation, How Often Should You Calibrate? Key Factors and Best Practices", "url": "https://www.fluke.com/en-us/learn/blog/calibration/how-often-should-you-calibrate", "supports": "Annual calibration as the most common requirement for test equipment, adjusted by application, regulation, and QA requirements; supports the 12 month typical interval as user/lab practice rather than a mandated value." } ], "guideUrl": "https://gaugelog.com/calibration/stopwatch" }, { "id": "stroboscope", "name": "Stroboscope", "synonyms": [ "strobe", "stroboscopic tachometer", "strobe light", "flash-rate meter", "stroboscope light" ], "category": "time-frequency", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 12, "max": 24 }, "usageBasedInterval": "Recalibrate after repair, and verify at a known flash rate before measurements feeding critical speed or acceptance decisions.", "intervalBasis": "No instrument-specific standard mandates the interval; it is a user decision based on use and criticality. Stroboscopes are calibrated against a frequency reference of higher accuracy than the unit under test, and annual calibration is the most common practice for electronic test instruments of this kind, with 12 to 24 months typical.", "intervalFactors": [ "Criticality: strobe used for quantitative speed measurement needs tighter control than qualitative motion inspection", "Number and spread of flash-rate points actually used across the range", "Electronic clock/oscillator aging and temperature exposure", "Operating environment (industrial vibration, heat, dust)", "As-found drift history at the calibrated frequencies" ], "standards": [ { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Framework under which accredited labs calibrate stroboscope flash rate against a traceable frequency reference and report uncertainty; the interval remains a user decision." } ], "sources": [ { "citation": "PCE Instruments, Stroboscope / Stroboscope Light (product category page with calibration guidance)", "url": "https://www.pce-instruments.com/us/measuring-instruments/test-meters/stroboscope-stroboscope-light-kat_40101.htm", "supports": "Calibration using a frequency counter of higher accuracy than the tested stroboscope, checking three or more measuring points, and measuring the internal clock generator signal rather than the light flashes." }, { "citation": "IET Labs (GenRad), Handbook of Stroboscopy", "url": "https://www.ietlabs.com/pdf/application_notes/Handbook_Stroboscopy.pdf", "supports": "Stroboscope operating principle, flash-rate ranges, and background on stroboscopic speed measurement." }, { "citation": "Fluke Corporation, How Often Should You Calibrate? Key Factors and Best Practices", "url": "https://www.fluke.com/en-us/learn/blog/calibration/how-often-should-you-calibrate", "supports": "Annual calibration as the most common requirement for test instruments, adjusted by application and QA requirements; supports the 12 month typical interval in the absence of an instrument-specific standard." } ], "guideUrl": "https://gaugelog.com/calibration/stroboscope" }, { "id": "surface-plate", "name": "Surface Plate", "synonyms": [ "granite surface plate", "surface table", "layout plate", "reference plane", "toolroom flat" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 36 }, "usageBasedInterval": "Monthly inspection with a repeat reading gage (Repeat-O-Meter) to detect developing wear spots between full calibrations; recalibrate when repeat readings differ from previous results or after the plate is moved or releveled.", "intervalBasis": "No standard specifies an interval. Manufacturer guidance (Tru-Stone) is a full recalibration within 1 year of purchase, shortened to 6 months under heavy use, after which the interval is extended or shortened based on results as allowed by the user's quality system; heavily used shop plates commonly stay on 6 to 12 month cycles while lightly used lab plates are extended.", "intervalFactors": [ "Workload: how many parts, gauges, and stands slide across the surface per day", "Cleanliness of the environment, since abrasive dust and grit act as a lapping compound under workpieces", "Concentration of use in one area of the plate, which creates local wear valleys rather than uniform wear", "Plate grade and tolerance (laboratory grade AA versus toolroom grade B) relative to the measurements made on it", "Thermal environment, because temperature gradients and direct sunlight distort flatness", "Whether the plate was recently moved, releveled, or resurfaced, which resets the calibration baseline" ], "standards": [ { "designation": "ASME B89.3.7", "title": "Granite Surface Plates", "relevance": "Covers granite surface plates for high-accuracy work including new certification, recertification in the field, and recertification after resurfacing; 2013 edition (reaffirmed 2023), modern successor to GGG-P-463c." }, { "designation": "GGG-P-463c", "title": "Federal Specification: Plate, Surface (Granite) (Inch and Metric)", "relevance": "Classic 1973 US federal specification defining flatness grades and accuracy requirements for granite surface plates; recommends monitoring with a repeat reading gage. Made inactive when ASME B89.3.7 was published in 2013 but still widely cited on calibration certificates." }, { "designation": "ISO 8512-2", "title": "Surface plates - Part 2: Granite", "relevance": "Specifies requirements for granite surface plates from 160 mm x 100 mm to 2500 mm x 1600 mm in accuracy grades 0, 1, 2, and 3; 1990 edition, confirmed 2022." } ], "sources": [ { "citation": "Tru-Stone Technologies (granite surface plate manufacturer), Frequently Asked Questions", "url": "https://www.tru-stone.com/faq", "supports": "Interval claim: full recalibration within 1 year of purchase, shortened to 6 months for heavy use, then extended or shortened per the quality system; monthly Repeat-o-Meter inspection to detect developing wear spots." }, { "citation": "Federal Specification GGG-P-463c, Plate, Surface (Granite), US General Services Administration, 1973", "url": "https://willrich.com/wp-content/uploads/2014/04/FedSpecGGG-P-463c.pdf", "supports": "Standard confirmation: flatness grades and accuracy requirements; recommendation to monitor flatness with a repeat reading gage and recalibrate when repeat readings change." }, { "citation": "ASME B89.3.7-2013, Granite Surface Plates, The American Society of Mechanical Engineers", "url": "https://webstore.ansi.org/Standards/ASME/asmeb892013", "supports": "Standard confirmation: covers new certification, field recertification, and recertification after resurfacing of granite surface plates, with traceability and measurement uncertainty requirements." }, { "citation": "ISO 8512-2:1990, Surface plates - Part 2: Granite, International Organization for Standardization", "url": "https://www.iso.org/standard/15737.html", "supports": "Standard confirmation: granite surface plate sizes and accuracy grades 0 to 3, applicable to plates in use and reconditioned plates." } ], "guideUrl": "https://gaugelog.com/calibration/surface-plate" }, { "id": "surface-roughness-tester", "name": "Surface Roughness Tester", "synonyms": [ "profilometer", "stylus profilometer", "surface finish tester", "roughness gauge", "surface texture tester" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Verify the tester against a certified roughness reference specimen before use or daily in production; recheck immediately after stylus replacement, drops, or readings outside the expected tolerance window.", "intervalBasis": "No standard prescribes an interval. Instrument suppliers such as Qualitest recommend a calibration check every six to twelve months for any model of surface roughness tester, combined with routine verification against a certified specimen; the exact cycle is a user decision based on usage and drift history.", "intervalFactors": [ "Stylus tip wear rate, driven by how abrasive and hard the measured surfaces are", "Shop-floor versus lab use, since portable testers accumulate handling damage and drive-unit wear faster", "Criticality of the Ra/Rz tolerances being certified, e.g. sealing or bearing surfaces", "As-found drift relative to the typical plus or minus 10 percent acceptance window on the reference specimen", "Measurement volume: number of traces per day wears both stylus and traverse mechanism", "Condition and calibration status of the reference specimens themselves, which also wear with repeated use" ], "standards": [ { "designation": "ISO 5436-1", "title": "Geometrical Product Specifications (GPS) - Surface texture: Profile method; Measurement standards - Part 1: Material measures", "relevance": "Specifies the material measures (reference specimens, types A through D) used to calibrate the metrological characteristics of stylus surface texture instruments; 2000 edition, confirmed 2024." }, { "designation": "ASME B46.1", "title": "Surface Texture (Surface Roughness, Waviness, and Lay)", "relevance": "US standard defining surface texture parameters, measurement methods, and precision reference specimens for calibrating stylus instruments; current edition 2019." }, { "designation": "ISO 3274", "title": "Geometrical Product Specifications (GPS) - Surface texture: Profile method - Nominal characteristics of contact (stylus) instruments", "relevance": "Defines the nominal characteristics of the stylus instruments whose calibration ISO 5436-1 material measures support." } ], "sources": [ { "citation": "Qualitest USA, \"The Guide to Calibrating a Surface Roughness Tester\" (instrument supplier guide)", "url": "https://qualitest.us/blogs/insight/how-to-calibrate-surface-roughness-tester", "supports": "Interval claim: recommends a calibration check every six to twelve months for any model; also supports the procedure (positioning, three or more verification measurements, gain adjustment) and the roughly plus or minus 10 percent acceptance window." }, { "citation": "NIST, \"NIST Surface Roughness and Step Height Calibrations\" (calibration service description, National Institute of Standards and Technology)", "url": "https://www.nist.gov/system/files/documents/pml/div683/grp02/nistsurfcalib.pdf", "supports": "Procedure grounding: national-level calibration of roughness and step height specimens that serve as the traceable references for roughness tester calibration." }, { "citation": "ISO 5436-1:2000, Geometrical Product Specifications (GPS) - Surface texture: Profile method; Measurement standards - Part 1: Material measures, International Organization for Standardization", "url": "https://www.iso.org/standard/21978.html", "supports": "Standard confirmation: defines the material measures used as measurement standards for calibrating stylus surface texture instruments per ISO 3274." }, { "citation": "ANSI Blog (American National Standards Institute), \"ASME B46.1-2019: Surface Texture (Roughness, Waviness, Lay)\"", "url": "https://blog.ansi.org/ansi/asme-b46-1-2019-surface-texture-roughness-waviness/", "supports": "Standard confirmation: current edition and scope of ASME B46.1 covering surface texture measurement and reference specimens." } ], "guideUrl": "https://gaugelog.com/calibration/surface-roughness-tester" }, { "id": "tachometer", "name": "Tachometer", "synonyms": [ "tach", "RPM meter", "rev counter", "optical tachometer", "contact tachometer", "laser tachometer" ], "category": "time-frequency", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 12, "max": 24 }, "usageBasedInterval": "Verify against a known reference speed after any drop or optical-head damage, and before speed measurements that feed a critical control or acceptance decision.", "intervalBasis": "No instrument-specific standard fixes the tachometer interval; it is a risk-based user decision. Calibration labs and ISO 17025 service providers commonly perform annual calibration against a traceable RPM/frequency reference, with 12 to 24 months typical depending on use and criticality.", "intervalFactors": [ "Criticality: speed measurements used for machine control or product acceptance justify tighter intervals", "Sensing type: optical/laser heads exposed to dust, vibration, or misalignment may drift faster than electronically referenced units", "Operating environment (industrial vibration, temperature, contamination)", "Range and resolution used relative to instrument specification", "As-found drift history across calibration points" ], "standards": [ { "designation": "ISO/IEC 17025", "title": "General requirements for the competence of testing and calibration laboratories", "relevance": "Framework under which accredited labs calibrate tachometers against traceable references and report uncertainty; does not set the interval, which remains a user decision." } ], "sources": [ { "citation": "Calibration Awareness, Digital Tachometer Calibration Procedure - Non-contact type Using Fluke 754 Process Calibrator", "url": "https://calibrationawareness.com/digital-tachometer-calibration-procedure-non-contact-type-using-fluke-754-process-calibrator", "supports": "Comparison against a traceable reference frequency/RPM source (simulated signal with LED for non-contact types) and calibration-point/procedure detail." }, { "citation": "Justervesenet (Norwegian Metrology Service), Tachometer calibration service", "url": "https://www.justervesenet.no/en/calibration-of-measuring-instruments/tachometer/", "supports": "National-metrology-institute calibration by comparison with a traceable reference frequency, using optical, contact, or simulated-signal methods." }, { "citation": "Techmaster Electronics, Tachometer Calibration Guide: ISO 17025 Standards & RPM Accuracy", "url": "https://techmaster.us/tachometer-calibration-guide-iso-17025-standards-rpm-accuracy/", "supports": "ISO 17025 calibration practice and the standard 12 month interval commonly applied to tachometers." } ], "guideUrl": "https://gaugelog.com/calibration/tachometer" }, { "id": "tape-measure", "name": "Tape Measure", "synonyms": [ "measuring tape", "tape rule", "steel tape", "pocket tape", "surveyor's tape" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 36 }, "usageBasedInterval": "Recalibrate or replace immediately after kinking, hook damage, or a broken/stretched blade; tapes used in legal trade are subject to the verification regimes of NIST Handbook 44 (US) or EU MID national requirements rather than a fixed lab interval.", "intervalBasis": "No standard sets a normative recalibration interval for tape measures. Calibration provider Techmaster states that most quality systems calibrate a measuring tape every 12 months, and sooner after repair, overload, or heavy use. Shorter or longer intervals are a risk-based user decision per ILAC-G24 / OIML D 10, driven by usage, measurement criticality, and any legal metrology verification requirements that apply to tapes used in trade.", "intervalFactors": [ "Wear and play in the sliding end hook, which directly shifts the zero point for inside and outside measurements", "Blade damage from kinks, twists, or dirt in the case, common with rough field and construction use", "Whether measurements are made under controlled tension: OIML R 35 / MID accuracy applies at a specified tractive force (50 N for tapes of 5 m and longer)", "Temperature exposure in field use, since steel tape length changes with temperature relative to the 20 degrees C reference", "Use in trade or contractual measurement, which raises criticality and may invoke legal metrology verification requirements" ], "standards": [ { "designation": "OIML R 35-1", "title": "Material measures of length for general use. Part 1: Metrological and technical requirements", "relevance": "International recommendation defining accuracy classes and maximum permissible errors for tape measures and other material measures of length; the class MPE is the usual acceptance criterion at calibration." }, { "designation": "Directive 2014/32/EU, Annex X (MI-008)", "title": "EU Measuring Instruments Directive, instrument-specific requirements for material measures", "relevance": "EU legal metrology requirements for material measures of length, including accuracy classes, the 50 N tractive force condition for tapes of 5 m and longer, and the 20 degrees C reference temperature." }, { "designation": "NIST Handbook 44", "title": "Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices", "relevance": "US legal metrology tolerances for linear measures used in trade, for example a 6 ft tape must be accurate within 1/32 in." } ], "sources": [ { "citation": "Techmaster Electronics, \"Measuring Tape Calibration\", accredited calibration service guide", "url": "https://techmaster.us/measuring-tape-calibration/", "supports": "Backs the interval claim: most quality systems calibrate a measuring tape every 12 months, and sooner after repair, overload, or heavy use, with a documented multi-point comparison under ISO/IEC 17025 using NIST-traceable references." }, { "citation": "OIML R 35-1, Edition 2007, Material measures of length for general use, Part 1: Metrological and technical requirements, International Organization of Legal Metrology", "url": "https://www.oiml.org/en/files/pdf_r/r035-1-e07.pdf", "supports": "Backs the standards listing, accuracy classes, tension and reference temperature conditions used in the procedure and interval factors." }, { "citation": "NIST, \"How Do You Ensure That a Tape Measure Is Accurate?\", National Institute of Standards and Technology web article", "url": "https://www.nist.gov/how-do-you-measure-it/how-do-you-ensure-tape-measure-accurate", "supports": "Backs the procedure description (graduations examined under a microscope against a laser reference system, deviations recorded as corrections) and the NIST Handbook 44 tolerance example of 1/32 in on a 6 ft tape." }, { "citation": "Directive 2014/32/EU of the European Parliament and of the Council (Measuring Instruments Directive), Annex X, Material Measures (MI-008)", "url": "https://lexparency.org/eu/32014L0032/ANX_X/", "supports": "Backs the EU legal metrology standard listing: accuracy classes for material measures of length, the 50 N tractive force requirement for tapes of 5 m and longer, and the 20 degrees C reference temperature." } ], "guideUrl": "https://gaugelog.com/calibration/tape-measure" }, { "id": "temperature-data-logger", "name": "Temperature Data Logger", "synonyms": [ "temperature logger", "electronic data logging monitor (EDLM)", "temperature recorder", "cold chain logger", "USB temperature logger" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Single-use EDLMs with sealed limited-life batteries are not designed to be recalibrated and are replaced instead; reusable loggers must carry a calibration valid within the current year before each mapping or qualification study per WHO guidance.", "intervalBasis": "WHO Technical Supplement 8 to TRS 961 Annex 9 requires mapping loggers to hold a NIST-traceable 3-point calibration valid within the current year and states that calibration should be done annually for recalibratable loggers, which is the norm across GDP/GxP practice; non-regulated users sometimes stretch toward 24 months, and 6 months appears where tolerances are tight.", "intervalFactors": [ "Regulated GxP or cold chain use, where annual calibration with a valid certificate is an audit expectation, versus non-regulated monitoring", "Required accuracy: WHO mapping work demands error of no more than plus or minus 0.5 C at each calibration point, leaving little drift budget", "Exposure to temperature extremes, condensation, or physical abuse during shipments", "As-found drift history across the fleet; consistent in-tolerance results can support interval extension under ILAC-G24 methods", "Battery condition and sensor type, since some sealed single-use loggers cannot be recalibrated at all" ], "standards": [ { "designation": "EN 12830:2018", "title": "Temperature recorders for the transport, storage and distribution of temperature sensitive goods - Tests, performance, suitability", "relevance": "Product standard covering the full recording system (sensor, recorder, data handling) from -80 to +85 C for cold chain applications" }, { "designation": "EN 13486:2023", "title": "Temperature recorders and thermometers for measuring the ambient or internal temperature for the transport, storage and distribution of temperature sensitive goods - Periodic verification", "relevance": "Companion standard specifying the periodic verification procedure against the class requirements of EN 12830" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for adjusting intervals from as-found history where no regulatory interval applies" } ], "sources": [ { "citation": "WHO Technical Report Series No. 961, Annex 9, Technical Supplement 8: Temperature mapping of storage areas, World Health Organization", "url": "https://cdn.who.int/media/docs/default-source/medicines/norms-and-standards/guidelines/distribution/trs961-annex9-supp8.pdf", "supports": "Interval claim: loggers must have a NIST-traceable 3-point calibration valid within the current year and calibration should be done annually; also the plus or minus 0.5 C acceptance criterion, 3-point bracketing scheme, and note that sealed single-use EDLMs are not recalibrated" }, { "citation": "EN 12830:2018, Temperature recorders for the transport, storage and distribution of temperature sensitive goods - Tests, performance, suitability, CEN", "url": "https://standards.iteh.ai/catalog/standards/cen/b6c1bd4b-fafb-41ee-9f9c-e729e4ca7c97/en-12830-2018", "supports": "Product standard scope for cold chain temperature recorders (-80 to +85 C, full recording system) cited in standards" }, { "citation": "BS EN 13486:2023, Temperature recorders and thermometers for measuring the ambient or internal temperature for the transport, storage and distribution of temperature sensitive goods - Periodic verification, BSI/CEN", "url": "https://www.en-standard.eu/bs-en-13486-2023-temperature-recorders-and-thermometers-for-measuring-the-ambient-or-internal-temperature-for-the-transport-storage-and-distribution-of-temperature-sensitive-goods-periodic-verification/", "supports": "Existence and scope of the periodic verification standard for temperature recorders referenced in standards and procedure" } ], "guideUrl": "https://gaugelog.com/calibration/temperature-data-logger" }, { "id": "thermal-imager", "name": "Thermal Imager", "synonyms": [ "thermal imaging camera", "infrared camera", "thermographic camera", "IR camera", "thermal camera" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Perform in-house accuracy checks against a stable blackbody between laboratory calibrations, and recalibrate after mechanical shock or any lens, filter, or detector service.", "intervalBasis": "No standard sets a normative interval for thermal imagers. Teledyne FLIR states that it recommends annual calibration for most applications, and calibration labs follow that guidance, so 12 months is the common manufacturer-based starting point, adjusted per ILAC-G24 / OIML D 10.", "intervalFactors": [ "Whether the camera is used for quantitative temperature measurement (condition monitoring, electrical inspection, R&D) or only for qualitative imaging", "Accuracy tolerance in use: typical specs of plus or minus 2 C or 2 percent leave little margin for drift in tight applications", "Mechanical shock and vibration in field service, and any lens, filter, or detector change, which invalidates the radiometric measurement model", "Operating temperature range extremes and rapid ambient transitions that stress the internal compensation", "As-found deviation history from prior certificates at low, mid, and high blackbody points" ], "standards": [ { "designation": "VDI/VDE 5585 Blatt 2", "title": "Technical temperature measurement - Temperature measurements with thermographic cameras - Calibration", "relevance": "Published guideline describing calibration methods for thermographic cameras used for quantitative surface temperature measurement (VDI/VDE guideline, the primary dedicated calibration document for this instrument class)" }, { "designation": "ASTM E1862", "title": "Standard Practice for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers", "relevance": "Defines the reflector and direct methods for determining reflected apparent temperature, a required correction when verifying imager accuracy against a source" }, { "designation": "ILAC-G24 / OIML D 10:2022", "title": "Guidelines for the determination of recalibration intervals of measuring equipment", "relevance": "Methodology for setting and reviewing the recalibration interval in the absence of a normative interval" } ], "sources": [ { "citation": "Teledyne FLIR, How Do You Calibrate a Thermal Imaging Camera? (flir.com Discover article)", "url": "https://www.flir.com/discover/professional-tools/how-do-you-calibrate-a-thermal-imaging-camera/", "supports": "Interval claim: states FLIR recommends annual calibration for most applications; also uniformity correction, temperature correlation against blackbodies, and why self-tests cannot replace laboratory calibration" }, { "citation": "VDI/VDE 5585 Blatt 2, Technical temperature measurement - Temperature measurements with thermographic cameras - Calibration, VDI/VDE", "url": "https://www.vdi.de/en/home/vdi-standards/details/vdivde-5585-blatt-2-technical-temperature-measurement-temperature-measurements-with-thermographic-cameras-calibration", "supports": "Existence and scope of the dedicated calibration guideline for thermographic cameras cited in standards and procedure" }, { "citation": "ILAC-G24 / OIML D 10, Edition 2022, Guidelines for the determination of recalibration intervals of measuring equipment, ILAC/OIML", "url": "https://www.oiml.org/en/files/pdf_d/d010-e22.pdf", "supports": "Interval basis framing: interval is a risk-based user decision reviewed against as-found history" } ], "guideUrl": "https://gaugelog.com/calibration/thermal-imager" }, { "id": "thermocouple", "name": "Thermocouple", "synonyms": [ "TC", "thermocouple probe", "type K thermocouple", "thermocouple sensor", "thermoelement" ], "category": "temperature-humidity", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 1, "max": 24 }, "usageBasedInterval": "In high-temperature service, base metal thermocouples are commonly replaced on a use-based schedule rather than recalibrated; AMS 2750 style pyrometry regimes limit thermocouple uses and time in service.", "intervalBasis": "No general normative interval exists; a 1-year cycle is typical for mild service below about 200 C, while base metal sensors above 1000 C may need monthly calibration or be treated as single-use, and noble metal types get roughly 6-month checks (Dearto calibration guidance). Sector standards such as SAE AMS2750 impose their own normative recalibration intervals and use limits for heat-treat pyrometry.", "intervalFactors": [ "Operating temperature dominates: service above about 1000 C can drive base metal types (K, J, E) to monthly calibration or one-time use, while service below 200 C supports annual cycles", "Base metal versus noble metal construction: types R, S, and B are more stable but still need periodic checks for contamination", "Inhomogeneity develops in wire exposed to steep temperature gradients, so physical relocation of the measuring junction can invalidate the calibration", "Exposure to corrosive or reducing atmospheres and mechanical vibration accelerates drift", "Heat-treatment applications under SAE AMS2750 or CQI-9 must follow those documents' fixed recalibration intervals and thermocouple use limits instead of a self-chosen cycle" ], "standards": [ { "designation": "IEC 60584-1", "title": "Thermocouples, Part 1: EMF specifications and tolerances", "relevance": "Defines reference emf-temperature functions and tolerance Classes 1, 2, and 3 for standardized thermocouple types" }, { "designation": "ASTM E230/E230M", "title": "Standard Specification for Temperature-Electromotive Force (emf) Tables for Standardized Thermocouples", "relevance": "US reference tables and standard/special tolerance limits for thermocouple types B, E, J, K, N, R, S, T, and C" }, { "designation": "ASTM E220", "title": "Standard Test Method for Calibration of Thermocouples By Comparison Techniques", "relevance": "The calibration method: comparison with a reference thermometer over approximately -196 C to 1700 C" }, { "designation": "SAE AMS2750", "title": "Pyrometry", "relevance": "Sets normative calibration intervals, tolerances, and use limits for temperature sensors in aerospace heat treatment" } ], "sources": [ { "citation": "Thermocouple Calibration: Methods, Equipment, and Standards for Industrial Applications, Dearto", "url": "https://www.dearto.com/thermocouple-calibration/", "supports": "The interval claims: 1-year cycle typical for mild processes below 200 C, monthly or one-time use for base metal sensors above 1000 C, 6-month checks for noble metal types, and deferring to AMS 2750 / CQI-9 for sector-specific intervals; also the comparison method procedure" }, { "citation": "ASTM E220, Standard Test Method for Calibration of Thermocouples By Comparison Techniques, ASTM International", "url": "https://www.astm.org/Standards/E220.htm", "supports": "The comparison calibration procedure and its applicable range of approximately -196 C to 1700 C" }, { "citation": "IEC 60584-1, Thermocouples, Part 1: EMF specifications and tolerances, Edition 3.0, International Electrotechnical Commission", "supports": "Reference functions and tolerance classes used as acceptance criteria" }, { "citation": "AMS2750E Heat Treatment Standard and Calibration, Beamex blog", "url": "https://blog.beamex.com/ams2750e-heat-treatment-standard-and-calibration", "supports": "SAE AMS2750 as a sector standard imposing normative calibration requirements for heat-treatment temperature sensors (usage-based interval and interval factors)" } ], "guideUrl": "https://gaugelog.com/calibration/thermocouple" }, { "id": "thread-gauge", "name": "Thread Gauge", "synonyms": [ "thread gage", "thread plug gauge", "thread ring gauge", "go/no-go thread gauge", "screw thread gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 3, "max": 24 }, "usageBasedInterval": "Shorten to 3-6 months for gauges making more than roughly 50 checks per day; recalibrate outside the cycle after drops, galling, or a noticeable change in gauging feel, and consider use counts when gauging hardened or abrasive materials.", "intervalBasis": "No thread standard mandates a recalibration interval. Calibration provider Techmaster reports that most quality systems calibrate a thread plug gauge every 12 months, moving to 3-6 month intervals for high-use gauges (over about 50 checks per day) and recalibrating sooner after repair, overload, or heavy use; the interval is a risk-based user decision per ILAC-G24 / OIML D 10, adjusted from the as-found wear trend.", "intervalFactors": [ "Daily gauging volume: thread flanks wear a measurable amount with every engagement, so production-line gauges drift far faster than inspection-room gauges", "Hardness and abrasiveness of the parts checked; gauging heat-treated fasteners wears the gauge faster than gauging aluminum", "Thread tolerance class being verified (for example 6H/6g or finer), where small pitch diameter wear already exceeds the gauge tolerance", "Exposure to cutting fluids, dust, and thermal cycling on the shop floor, which accelerates wear and corrosion", "As-found wear trend from previous calibrations, especially how close the go member is to its wear limit", "Consequence of a wrong accept/reject decision, such as threaded joints in safety-critical fastener applications" ], "standards": [ { "designation": "ASME B1.2", "title": "Gages and Gaging for Unified Inch Screw Threads", "relevance": "Defines the dimensions and tolerances of gauges for Unified inch screw threads and the gauging practice (for example no-go acceptance limited to a maximum number of turns); acceptance criteria for calibrating unified thread gauges." }, { "designation": "ISO 1502:1996", "title": "ISO general-purpose metric screw threads - Gauges and gauging", "relevance": "Specifies go/no-go gauges and gauging practice for ISO metric screw threads, including gauge dimensions and wear limits used at recalibration." }, { "designation": "ASME B1.3-2007", "title": "Screw Thread Gaging Systems for Acceptability: Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ)", "relevance": "Defines the gauging systems that determine which thread characteristics must be inspected and with which gauges, the framework within which calibrated thread gauges are applied." } ], "sources": [ { "citation": "Techmaster Electronics, \"Thread Plug Gauge Calibration: The Audit-Ready Guide\", accredited calibration service guide", "url": "https://techmaster.us/thread-plug-gauge-calibration-the-audit-ready-guide/", "supports": "Backs the interval claim (the industry standard is 12 months; for high-use gauges over 50 checks per day a 3-month or 6-month interval is recommended) and the procedure: ultrasonic cleaning, 10x inspection, three-wire method, universal length machine, temperature stabilization, as-found measurement, and certificate issuance." }, { "citation": "Quality Magazine, \"Calibrating Standard Threaded Gages\" (May 2020)", "url": "https://www.qualitymag.com/articles/96041-calibrating-standard-threaded-gages", "supports": "Backs the procedure framing: pitch diameter as the most critical measurement on a threaded plug gauge, the three-wire method as the ASME-defined procedure for checking thread pitch diameter, and major diameter checks during calibration." }, { "citation": "ISO 1502:1996, ISO general-purpose metric screw threads - Gauges and gauging, International Organization for Standardization", "url": "https://www.iso.org/standard/6092.html", "supports": "Backs the standards listing: specification of go/no-go gauges and gauging for ISO metric threads, including tolerance zones and permissible wear, used as acceptance criteria for metric thread gauge calibration." }, { "citation": "ASME B1.2, Gages and Gaging for Unified Inch Screw Threads, The American Society of Mechanical Engineers", "url": "https://www.asme.org/codes-standards/find-codes-standards/b1-2-gages-gaging-unified-inch-screw-threads", "supports": "Backs the standards listing: gauge specifications, dimensions, and gauging practice for Unified inch screw threads, including no-go engagement limits." } ], "guideUrl": "https://gaugelog.com/calibration/thread-gauge" }, { "id": "torque-tester", "name": "Torque Tester", "synonyms": [ "torque analyzer", "torque transducer", "torque meter", "torque measuring device", "torque calibration analyzer" ], "category": "force-torque", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Recalibrate immediately after overload beyond rated capacity, drops, or repair; many labs also run interim checks with a calibrated master torque wrench or check standard between calibrations.", "intervalBasis": "No fixed normative interval exists for torque measuring devices; calibration providers report that most manufacturers recommend calibration every 6 to 12 months, with the classification under BS 7882 valid for the device as calibrated. The interval is a user decision reviewed against as-found data.", "intervalFactors": [ "Throughput of tool checks: testers used daily to verify production torque tools accumulate loading cycles quickly", "Role as an in-house reference standard: if the tester calibrates other tools, its interval should be tighter than the tools it checks", "Overload events, drops, or repairs to the transducer or indicator, which require immediate recalibration", "BS 7882 class required (Class 0.05 through 5): tighter classes justify shorter intervals to protect the classification", "Stability shown across successive calibrations; documented low drift supports extending toward 12 months" ], "standards": [ { "designation": "BS 7882:2017", "title": "Method for calibration and classification of torque measuring devices", "relevance": "The governing method for calibrating and classifying static torque measuring devices, including transducers used to calibrate torque tools." }, { "designation": "ISO 6789-2:2017", "title": "Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty", "relevance": "Specifies requirements on the torque measurement devices used when calibrating hand torque tools, making tester calibration a prerequisite for ISO 6789 tool calibration." } ], "sources": [ { "citation": "Nagman Calibration Services LLP, \"Torque Tester Calibration: Ensuring Precision in Every Twist\"", "url": "https://www.nagman-calibration.com/torque-tester-calibration-ensuring-precision-in-every-twist/", "supports": "Backs the interval claim that most manufacturers recommend calibration every 6 to 12 months, plus recalibration triggers after repairs, drops, or heavy usage, and the general procedure and traceable reference equipment." }, { "citation": "BS 7882:2017, Method for calibration and classification of torque measuring devices, BSI", "url": "https://knowledge.bsigroup.com/products/method-for-calibration-and-classification-of-torque-measuring-devices-1", "supports": "Backs the calibration method, calculation of results, and the classification of torque measuring devices in static mode, including the class system." }, { "citation": "NPL Measurement Good Practice Guide No. 107, \"Guide to the calibration and testing of torque transducers\", National Physical Laboratory", "url": "https://eprintspublications.npl.co.uk/4092/1/MGPG107.pdf", "supports": "Backs the procedure elements for calibrating and testing torque transducers, including loading series and uncertainty considerations." } ], "guideUrl": "https://gaugelog.com/calibration/torque-tester" }, { "id": "torque-wrench", "name": "Torque Wrench", "synonyms": [ "click torque wrench", "torque spanner", "dial torque wrench", "digital torque wrench", "preset torque wrench" ], "category": "force-torque", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Recalibrate after 5,000 operations or 12 months, whichever comes first (ISO 6789 recommendation); shorten to about 2,500 operations or 6 months for safety-critical applications, and recalibrate immediately after drops, overload, or suspected damage.", "intervalBasis": "ISO 6789:2017 recommends recalibration at least every 12 months or every 5,000 operations, whichever comes first, as the default starting point; users may shorten this based on usage and criticality, and 6 months or 2,500 operations is common for safety-critical work.", "intervalFactors": [ "Operation count: high-volume assembly work reaches the 5,000-cycle trigger long before 12 months elapse", "Safety criticality of joints (aerospace, pressure systems, structural steelwork), where 6 months or 2,500 operations is common practice", "Drops, overloading beyond maximum scale, or use as a breaker bar, all of which require immediate recalibration regardless of schedule", "Storage practice: leaving click-type wrenches wound above their lowest setting stresses the spring and accelerates drift", "As-found pass/fail history against the tool's class tolerance at successive calibrations" ], "standards": [ { "designation": "ISO 6789-1:2017", "title": "Assembly tools for screws and nuts - Hand torque tools - Part 1: Requirements and methods for design conformance testing and quality conformance testing: minimum requirements for declaration of conformance", "relevance": "Defines tool classes, conformance requirements, and the basis for the 12 month / 5,000 operation recalibration recommendation." }, { "designation": "ISO 6789-2:2017", "title": "Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty", "relevance": "Specifies the calibration procedure and measurement uncertainty determination for hand torque tools." }, { "designation": "ASME B107.300", "title": "Torque Instruments", "relevance": "US performance and safety requirements for manually operated torque instruments used to control fastener tightness; consolidates ASME B107.14 (Hand Torque Tools), B107.28, and B107.29." } ], "sources": [ { "citation": "AIMS Industrial Supplies, \"Torque Wrench Calibration: Standards, Intervals & Certificate Guide\"", "url": "https://aimsindustrial.com.au/blogs/product-guides/torque-wrench-calibration", "supports": "Backs the interval claim: ISO 6789 calibration at least every 12 months or 5,000 operations, whichever comes first, plus 6 months / 2,500 operations for safety-critical applications and recalibration after drops or overload." }, { "citation": "ISO 6789-1:2017, Assembly tools for screws and nuts - Hand torque tools - Part 1, ISO", "url": "https://www.iso.org/standard/62549.html", "supports": "Backs the standard designation, title, and its role in conformance requirements for hand torque tools." }, { "citation": "ISO 6789-2:2017, Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty, ISO", "url": "https://www.iso.org/standard/62550.html", "supports": "Backs the calibration and uncertainty procedure steps in the outline." }, { "citation": "ASME, B107.14 - Hand Torque Tools (consolidated into ASME B107.300, Torque Instruments)", "url": "https://www.asme.org/codes-standards/find-codes-standards/b107-14-hand-torque-tools", "supports": "Backs the ASME B107.14/B107.300 designation and its scope covering manually operated torque wrenches and screwdrivers." } ], "guideUrl": "https://gaugelog.com/calibration/torque-wrench" }, { "id": "ultrasonic-thickness-gauge", "name": "Ultrasonic Thickness Gauge", "synonyms": [ "UT thickness gauge", "ultrasonic thickness meter", "wall thickness gauge", "D-meter", "UTM gauge" ], "category": "dimensional", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "usageBasedInterval": "Zero and velocity calibration on reference blocks of the test material at the start of each measurement session per ASTM E797 practice, plus field verification on a step wedge or calibration block before and during surveys; recalibrate after probe replacement or drops.", "intervalBasis": "BS EN 15317 recommends that all ultrasonic thickness gauges undergo an annual performance check, and manufacturer Cygnus states that recalibration is usually every 12 months using equipment traceable to national standards, adjusted per the owner's quality requirements.", "intervalFactors": [ "Transducer face wear from scanning rough, corroded, or hot surfaces, which shifts zero and degrades coupling", "Range of materials measured, since each material velocity setting must be established against known references", "Harsh field conditions (offshore, rope access, elevated temperature) that accelerate cable, probe, and connector damage", "Criticality of results, e.g. pressure equipment and marine class surveys where undetected thinning has high consequence", "As-found linearity and accuracy drift documented at previous performance checks", "Intensity of use: daily survey work versus occasional spot checks" ], "standards": [ { "designation": "ASTM E797/E797M", "title": "Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method", "relevance": "Defines the measurement practice, including calibration/standardization of the instrument on reference blocks of known thickness and the same material velocity; current edition 2021." }, { "designation": "BS EN 15317", "title": "Non-destructive testing - Ultrasonic testing - Characterization and verification of ultrasonic thickness measuring equipment", "relevance": "Specifies methods and acceptance criteria for verifying the performance of ultrasonic thickness gauges and recommends an annual performance check; current edition 2013." } ], "sources": [ { "citation": "Cygnus Instruments (ultrasonic thickness gauge manufacturer), Support FAQs", "url": "https://cygnus-instruments.com/support/faqs/", "supports": "Interval claim: recalibration is usually every 12 months with traceable equipment, and BS EN 15317 recommends all gauges undergo an annual performance check to ensure correct operation." }, { "citation": "ASTM E797/E797M-21, Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method, ASTM International", "url": "https://store.astm.org/e0797_e0797m-21.html", "supports": "Standard confirmation and procedure grounding: pulse-echo thickness measurement practice including standardization on reference blocks of known thickness and matching material velocity." }, { "citation": "BS EN 15317:2013, Non-destructive testing - Ultrasonic testing - Characterization and verification of ultrasonic thickness measuring equipment, British Standards Institution / CEN", "url": "https://www.en-standard.eu/bs-en-15317-2013-non-destructive-testing-ultrasonic-testing-characterization-and-verification-of-ultrasonic-thickness-measuring-equipment/", "supports": "Standard confirmation: methods and acceptance criteria for assessing the performance of pulse-echo ultrasonic thickness instruments, underpinning the annual performance check and the linearity/accuracy evaluation in the procedure." }, { "citation": "Cygnus Instruments, \"Ultrasonic Thickness Gauge Calibration Procedure\"", "url": "https://us.cygnus-instruments.com/ultrasonic-thickness-gauge-calibration/", "supports": "Procedure grounding: equipment preparation and inspection, selection of calibration blocks of known thickness covering the measurement range, sound velocity setting, and zero calibration." } ], "guideUrl": "https://gaugelog.com/calibration/ultrasonic-thickness-gauge" }, { "id": "tensile-testing-machine", "name": "Universal Testing Machine", "synonyms": [ "UTM", "tensile testing machine", "tensile tester", "compression testing machine", "materials testing machine" ], "category": "force-torque", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Reverify immediately after relocation of the machine, after repair or adjustment of the force-measuring system, and after suspected overload events, regardless of elapsed calendar time.", "intervalBasis": "ISO 7500-1 and ASTM E4 both recommend verifying the force-measuring system at intervals of no more than 12 months, unless machine-specific reasons justify otherwise, as summarized by accredited calibration provider ZwickRoell. Reverification is also required after the machine is relocated, repaired, or adjusted.", "intervalFactors": [ "Relocation of the machine triggers immediate reverification regardless of elapsed time", "Repairs or adjustments to the load cell, frame, or force indication electronics invalidate the current verification", "High test throughput and frequent operation near full capacity accelerate load cell drift", "Accidental overloads or specimen failures that shock-load the force transducer", "Accreditation requirements (for example an ISO/IEC 17025 scope) that fix the verification cycle", "As-found classification history: repeated results near the Class 1 error limits argue for a shorter cycle" ], "standards": [ { "designation": "ISO 7500-1:2018", "title": "Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Calibration and verification of the force-measuring system", "relevance": "Primary international standard defining the force calibration and classification procedure for tension/compression testing machines" }, { "designation": "ASTM E4", "title": "Standard Practices for Force Calibration and Verification of Testing Machines", "relevance": "North American practice for force calibration and verification of static and quasi-static testing machines, with a plus/minus 1 percent accuracy requirement" }, { "designation": "ISO 376:2011", "title": "Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines", "relevance": "Governs the calibration and classification of the reference force-proving instruments (load cells, proving rings, dynamometers) used to verify the machine" } ], "sources": [ { "citation": "ZwickRoell, \"ISO 7500-1, ASTM E4 Load Cell Calibration\" (accredited calibration service page)", "url": "https://www.zwickroell.com/services/calibration/iso-7500-1-astm-e4-load-cell-calibration/", "supports": "The 12-month interval: states ISO 7500-1 and ASTM E4 recommend an interval of no more than 12 months unless otherwise specified, plus recalibration after relocation; also the measuring points from 0.1 to 100 percent of force range" }, { "citation": "ISO 7500-1:2018, Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1, International Organization for Standardization", "url": "https://www.iso.org/standard/72572.html", "supports": "Existence and scope of the governing calibration/verification standard for the force-measuring system" }, { "citation": "ASTM E4, Standard Practices for Force Calibration and Verification of Testing Machines, ASTM International", "url": "https://store.astm.org/e0004-21.html", "supports": "Scope of force calibration and verification practice and the plus/minus 1 percent accuracy requirement for force-indicating systems" }, { "citation": "ISO 376:2011, Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines, International Organization for Standardization", "url": "https://www.iso.org/standard/44661.html", "supports": "Requirement that reference force-proving instruments used for machine verification are calibrated and classified per ISO 376" } ], "guideUrl": "https://gaugelog.com/calibration/tensile-testing-machine" }, { "id": "vacuum-gauge", "name": "Vacuum Gauge", "synonyms": [ "vacuum gage", "Pirani gauge", "capacitance manometer", "capacitance diaphragm gauge", "ionization gauge", "thermocouple gauge" ], "category": "pressure-vacuum", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 12 }, "usageBasedInterval": "Recalibrate or verify early after process excursions or contamination events, when a spot check against a portable reference shows drift beyond about 10 percent at a reference point, or after roughly 500 process cycles on heavily used production gauges per manufacturer guidance.", "intervalBasis": "No standard fixes an interval; ISO 3567 defines the comparison method but leaves frequency to the user. Vacuum gauge manufacturer guidance (Poseidon Scientific) recommends annual verification for research and low-volume labs and full calibration every 6 to 12 months for semiconductor and PVD production, with earlier action on observed drift.", "intervalFactors": [ "Process contamination: deposition byproducts, oil backstreaming, or corrosive gases coat Pirani filaments and CDG diaphragms and accelerate drift", "Drift greater than about 10 percent at a reference check point is a trigger for immediate recalibration in manufacturer guidance", "Duty in production tools: high cycle counts (for example after several hundred pump-down cycles) or electrode discoloration justify earlier calibration", "Gas species differences between calibration gas (typically nitrogen) and process gas add correction uncertainty for indirect gauges", "Criticality of the vacuum window: a gauge gating a safety interlock or product-quality step needs a tighter cycle than a roughing-line indicator", "Exposure to atmosphere venting cycles and mechanical shock on portable gauges" ], "standards": [ { "designation": "ISO 3567:2011", "title": "Vacuum gauges - Calibration by direct comparison with a reference gauge", "relevance": "Defines the physical, technical, and metrological conditions for calibrating vacuum gauges by comparison with a traceable reference gauge" } ], "sources": [ { "citation": "Poseidon Scientific, \"Vacuum Gauge Calibration: Best Practices Guide\"", "url": "https://poseidon-scientific.com/blog/vacuum-gauge/maintenance-troubleshooting/vacuum-gauge-calibration-best-practices/", "supports": "The interval: annual verification for research/low-volume labs, every 6 to 12 months for semiconductor/PVD production, quarterly spot checks plus annual full calibration for battery/heat-treatment lines, and the drift-greater-than-10-percent and cycle-count triggers; also the comparison method against a NIST-traceable CDG reference" }, { "citation": "ISO 3567:2011, Vacuum gauges - Calibration by direct comparison with a reference gauge, International Organization for Standardization", "url": "https://www.iso.org/standard/59372.html", "supports": "The standardized comparison calibration method and the requirement that the reference gauge have lower (or at least equal) measurement uncertainty than the unit under calibration" }, { "citation": "NIST publication: \"Recommended practice for calibrating vacuum gauges of the ionization type\" (Journal of Vacuum Science & Technology A review article)", "url": "https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925286", "supports": "Recommended practice for calibrating ionization-type vacuum gauges, supporting the comparison-calibration approach and reference-standard selection for high vacuum" } ], "guideUrl": "https://gaugelog.com/calibration/vacuum-gauge" }, { "id": "vibration-meter", "name": "Vibration Meter", "synonyms": [ "vibration analyzer", "vibration severity meter", "vibrometer", "vibration tester", "machinery vibration meter" ], "category": "acoustic-vibration", "typicalIntervalMonths": 12, "intervalRangeMonths": { "min": 6, "max": 24 }, "intervalBasis": "No standard mandates a calendar interval; calibration guides and laboratories generally recommend recalibrating vibration meters every 12 months, with shorter intervals for harsh service. The interval is a risk-based user decision per the ILAC-G24 / OIML D 10 methodology.", "intervalFactors": [ "Harsh industrial environments with heat, moisture, and dust that stress the transducer and cables", "Handling risk: dropped probes or magnet-mounted accelerometers snapping onto surfaces can shift sensitivity", "Criticality of decisions taken from readings, such as machine protection trips or acceptance tests against ISO severity limits", "Wear in connecting cables, connectors, and mounting hardware that changes the frequency response", "As-found drift history from previous certificates, which supports extending or shortening the interval" ], "standards": [ { "designation": "ISO 16063-21:2003", "title": "Methods for the calibration of vibration and shock transducers - Part 21: Vibration calibration by comparison to a reference transducer", "relevance": "Defines the comparison calibration method used to calibrate the meter's transducer and measuring chain on a vibration exciter, covering 0.4 Hz to 10 kHz" }, { "designation": "ISO 2954:2012", "title": "Mechanical vibration of rotating and reciprocating machinery - Requirements for instruments for measuring vibration severity", "relevance": "Specifies accuracy and performance requirements for vibration severity instruments that indicate RMS vibration velocity on rotating and reciprocating machinery" } ], "sources": [ { "citation": "ISO 16063-21:2003, Methods for the calibration of vibration and shock transducers - Part 21: Vibration calibration by comparison to a reference transducer, ISO", "url": "https://www.iso.org/standard/27053.html", "supports": "Existence and scope of the comparison calibration method and its 0.4 Hz to 10 kHz frequency range" }, { "citation": "How to Calibrate a Vibration Meter (ISO 16063 Procedure), CalibrationOS", "url": "https://calibrationos.com/guides/calibrate-vibration-meter", "supports": "Interval claim: typical calibration interval of 12 months; also the ISO 16063-21 comparison procedure, the 159.2 Hz reference frequency, and frequency response and linearity checks" }, { "citation": "ISO 2954:2012, Mechanical vibration of rotating and reciprocating machinery - Requirements for instruments for measuring vibration severity, ISO", "url": "https://www.iso.org/standard/21835.html", "supports": "Instrument accuracy and performance requirements for vibration severity instruments used as acceptance criteria" } ], "guideUrl": "https://gaugelog.com/calibration/vibration-meter" } ] }