What pressure units are used in the gauge pressure measurements?

Gauge pressure measurements specifically relate to the pressure of a system relative to the ambient atmospheric pressure. The unit most commonly used for gauge pressure is pounds per square inch gauge (psig). This unit expresses pressure in pounds per square inch above atmospheric pressure, allowing operators to directly measure how much pressure is exerted by a fluid or gas in a system without being influenced by atmospheric pressure.

In contrast, other options like psia, bar, and kPa can refer to absolute pressure measurements (psia), or they can be used in both gauge and absolute contexts but are not exclusively gauge pressure units. Understanding the context of pressure measurements is crucial, particularly in industrial refrigeration, where maintaining correct pressure levels is critical for system performance and safety.