Pressure Gauge

Pressure gauges are used throughout industry for process monitoring, quality testing, and safety applications. Mechanical gauges (Bourdon tube, diaphragm, bellows) convert pressure to mechanical displacement, which moves a pointer on a dial. Digital pressure gauges use electronic pressure sensors (strain gauge, piezoresistive, capacitive) and display readings on an LCD. Pressure transmitters output electrical signals (4-20 mA, 0-10V) for process control systems.

Calibration of pressure gauges is performed by applying known pressures and comparing the gauge readings. Reference standards include deadweight testers (primary standards that generate precise pressures using calibrated masses and pistons), precision digital pressure indicators, and pressure controllers. Calibration is performed at multiple points across the gauge range, typically at 0%, 25%, 50%, 75%, and 100% of full scale, both ascending and descending to check for hysteresis. The gauge accuracy class (per ASME B40.100 or EN 837) defines the allowable error.

For calibration management, pressure gauges are among the highest-volume instruments requiring calibration in process industries. The harsh environments (temperature extremes, vibration, corrosive media, pressure spikes) where pressure gauges operate make them prone to drift and damage. Calibration intervals range from 3 months for critical safety applications to 12 months for general industrial use. Overpressure events, physical damage, and exposure to incompatible media are common causes of failure. Process safety regulations (PSM, RMP) often specify calibration requirements for pressure instruments in safety-critical applications.