Pressure gauge calibration: how often, to which standards, and how
A pressure gauge is a mechanical dial instrument, most often based on a Bourdon tube, that indicates the gauge pressure of a gas or liquid in a process line or vessel. Mechanical wear, vibration, pulsation, and overpressure shift its indication over time, so periodic comparison against a deadweight tester or reference calibrator is required to keep readings within the gauge's accuracy grade.
Also known as: pressure gage, dial pressure gauge, analog pressure gauge, Bourdon tube gauge, test gauge
How often should a pressure gauge be calibrated?
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.
Where this number comes from
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.
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. Treat the interval above as a starting point for your own quality system, not a compliance requirement.
What shortens or lengthens the interval
- 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 relevant to pressure gauge calibration
US standard covering dial-type elastic element and digital pressure gauges, their accuracy grades, and gauge attachments
European standard defining accuracy classes, metrological requirements, and test methods for Bourdon tube pressure and vacuum gauges
Methodology for setting and adjusting the recalibration interval, since no gauge standard fixes one
Standards are referenced by designation and title. For normative requirements, always work from the current edition of the standard itself.
How a pressure gauge is calibrated
A typical pressure gauge calibration, in an accredited lab or in-house, follows this outline. The exact points, tolerances and paperwork come from the applicable standard and your own procedure.
- Mount the gauge in its normal orientation on a deadweight tester or pressure comparator, matching the pressure medium and minding the head-height correction between reference and gauge
- Exercise the gauge by applying full-scale pressure and releasing it before recording readings
- Apply pressure at increments of 0, 25, 50, 75, and 100 percent of span in rising then falling order to capture hysteresis, tapping the gauge lightly before each reading
- Record as-found readings of the gauge against the reference at every point in both directions
- Compare errors to the acceptance tolerance for the gauge's accuracy grade or class (per ASME B40.100 grade or EN 837-1 class)
- If out of tolerance, adjust the movement (span and linearization) or pointer and repeat the run to record as-left results
- Issue a calibration certificate with as-found/as-left data, environmental conditions, reference standard identification, and traceability
Reference equipment typically used
- Deadweight tester (pressure balance) or precision pressure comparator with reference gauge
- Pressure hand pump or pressure controller with fine adjustment
- Calibrated reference pressure indicator with accuracy typically 4 times better than the gauge under test
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Sources
- Ashcroft blog, "How Often Should I Check the Calibration of My Pressure Gauge?"
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
- Beamex white paper, "How to calibrate pressure gauges - 20 things you should consider"
Procedure details: exercising the gauge, number of calibration points, hysteresis (rising/falling), tapping, documentation, and traceability
- ASME B40.100-2022, Pressure Gauges and Gauge Attachments, American Society of Mechanical Engineers
Existence and scope of the US gauge standard consolidating dial and digital pressure gauge requirements
- BS EN 837-1:1998, Pressure gauges - Bourdon tube pressure gauges - Dimensions, metrology, requirements and testing, CEN/BSI
Scope and metrological requirements for Bourdon tube pressure and vacuum gauges up to 1600 bar