Comparing Absolute And Gauged Pressure Sensors

This technical note describes the difference between absolute and gauged pressure sensors and explains the proper use of each type of sensor in different applications. Provides a general illustration of the forces measured by a pressure sensor's internal strain gauge.

An absolute or non-vented pressure sensor measures all pressure forces detected by the strain gauge, including atmospheric pressure (P_ATM). The unit of measure is PSIA (pounds per square inch absolute), measured with respect to zero pressure. The back of an absolute pressure sensor is sealed from the atmosphere. Therefore, the front of the absolute pressure sensor responds to both atmospheric pressure and the pressure head of water above the sensor.

A gauged or vented pressure sensor eliminates the effects of atmospheric pressure because the vent tube in the cable allows atmospheric pressure to be applied to the back of the sensor. The unit of measure is PSIG (pounds per square inch gauge), measured with respect to atmospheric pressure.