Silicon Pressure Cell Fill Oil Volume Verification Methods
Confirm fill oil volume using pre- and post-injection micro-gravimetric mass checks combined with non-contact laser interferometric diaphragm dome profiling.
Pressure Transmitter Testing
Verification Procedure
Metrological verification confirms that a sensor performs within its specified accuracy limits over its operating range. Regular pressure transmitter testing compares the output of the device against a traceable reference standard. This process ensures that industrial control systems receive accurate process variables for safe operation.
The frequency of this procedure depends on the critical nature of the loop.
Standard Equipment
Reference instruments used in the field include digital test gauges and automated pressure controllers. During pressure transmitter testing, a pneumatic or hydraulic hand pump generates the required pressure, which is monitored by a high-accuracy reference sensor. The system records both the reference and the transmitter output at multiple points across the span.
This test is typically performed at five points rising and falling to identify hysteresis.
Performance Tolerance
Data evaluation checks the calculated errors against the maximum permissible error specified by the manufacturer. If the deviation during pressure transmitter testing exceeds the allowable limit, the instrument undergoes a zero and span adjustment to bring it back into calibration. This adjustment must be documented on a calibration certificate to maintain traceability.
The certificate ensures compliance with quality management systems such as ISO 9001.
Safety Rule
Hazard mitigation requires isolating the sensor from the process lines and safely venting any trapped pressure before beginning the test. Failure to isolate the device can release hazardous process fluids into the atmosphere or cause injury to the technician.