Piezoresistive Diaphragm Calibration Traceability and Proof Pressure Bounds
Calibration traceability requires unbroken deadweight references, while exceeding proof pressure bounds causes unrecoverable zero drift from metallic yielding.
Water Hammer
Pressure Surge
A rapid pressure transient in a fluid piping system occurs when a moving fluid is forced to stop or change direction suddenly. In industrial liquid monitoring, water hammer generates high-frequency shock waves that propagate through the fluid column and exceed the rated limits of inline pressure sensors.
Physical Process
The sudden closure of a valve converts the kinetic energy of the flowing fluid into potential energy in the form of a high-pressure wave. This wave travels back and forth along the pipe at the speed of sound in the medium. The peak pressure of the surge is proportional to the density of the fluid and the change in velocity.
Sensor Damage
The resulting shock can rupture the delicate sensing diaphragms of transmitter instruments. These failures require immediate replacement of the damaged hardware.
Preventative Measurement
Engineers use pressure snubbers and surge tanks to dampen these destructive transients before they reach the sensitive instrumentation. The installation of slow-closing valves also helps to prevent the formation of the pressure wave. Calibration technicians must inspect the sensor diaphragms for plastic deformation after any reported surge event.
This inspection ensures that the pressure sensor continues to operate within its original accuracy specification.