Pressure Measurement Scales

In industrial applications, pressure is expressed in many ways. Here we describe some of the common methods. In our discussion we will make reference to an illustration which illustrates comparison of a few scales. We will consider one section of the illustration at a time in our discussion.

Common Pressure Measurement Scale (left scale - top part)

This is the common “psig” scale. Notice that it starts at 0 and increases to higher numbers. If a gauge is calibrated in only psig, it will not show any numbers below zero. If you recall, we take the normal atmospheric conditions as “zero pressure”.

Summary: The common "psig" scale starts with its zero at atmospheric pressure and extends from zero to higher values.