Pressure Gauge Troubleshooting and Calibration Guide
Pressure gauge failures can lead to incorrect process decisions and safety risks. This guide covers common problems and calibration procedures.
I. Calibration Procedure
- Remove the gauge from service and vent to atmosphere to check zero. The pointer should rest within the zero tolerance band.
- Connect the gauge to a pressure calibrator or deadweight tester using appropriate fittings
- Apply pressure at increasing steps across the full range and record readings. Allow the gauge to stabilize at each point.
- Compare readings against the reference standard. Calculate the error at each point as a percentage of full scale.
- If the error exceeds the accuracy class specification, adjust the gauge (if adjustable) or replace it.
II. Common Failure Modes
Pointer Does Not Return to Zero: Indicates permanent deformation of the Bourdon tube from overpressure. Replace the gauge.
Erratic Pointer Movement: Check for loose linkage or worn movement. Liquid-filled gauges may have lost fill fluid through a leak.
Liquid-Filled Gauge with Bubble: Small bubble is normal for thermal expansion. Large bubble indicates fill fluid loss and the gauge should be replaced.
Blackened or Discolored Dial: Indicates the Bourdon tube has ruptured and process fluid has entered the case. Replace the gauge immediately and investigate the cause.
III. Replacement Criteria
- Bourdon tube rupture or leakage
- Pointer not returning to zero after venting
- Accuracy outside specification after adjustment attempt
- Broken or severely cracked glass
- Corrosion compromising the case integrity
