Establishing Measurement Traceability Chains for Industrial Pressure Transducers
Establishing pressure traceability requires calculating complete uncertainty budgets and enforcing accredited test ratios to prove sensor claims.
Line Pressure Effect
Differential Distortion
The change in the output of a differential pressure sensor that occurs when the system is subjected to high static pressure is a well known physical phenomenon. This phenomenon, referred to as the line pressure effect, causes both zero shifts and span shifts in the sensor’s measurement output. It occurs because the mechanical structure of the sensing capsule deforms slightly under the influence of the high static line pressure.
Sensor Calibration
Adjusting the instrument under representative process conditions is necessary to minimize the impact of this systematic error. Technicians mitigate the line pressure effect by performing a zero trim while the transmitter is exposed to the full working pressure of the system. This step ensures that the zero point is accurate when the process is running, even if a shift occurs when the system is depressurized.
System Validation
High static pressure environments require careful selection of transmitters designed to withstand extreme line pressures without significant performance loss. Evaluating the line pressure effect is critical in flow measurement applications where the differential pressure is small compared to the total line pressure. Proper assessment ensures that flow calculations remain accurate across varying process pressures.
Error Correction
Using built in static pressure sensors allows modern transmitters to compensate for these multi variable influences. This dynamic compensation reduces the line pressure effect automatically.