The formula to calculate the Gauge Pressure (Pg) is:
\[ Pg = Pa - Pat \]
Where:
Gauge pressure is the pressure measurement relative to the surrounding atmospheric pressure. It is the difference between the absolute pressure (Pa) and the atmospheric pressure (Pat). Gauge pressure is commonly used in various applications such as tire pressure measurement, where the pressure is expressed relative to the ambient air pressure.
Let's consider an example:
Using the formula to calculate Gauge Pressure:
\[ Pg = 120 - 100 = 20 \, \text{units} \]
This means that the gauge pressure is 20 units.