If a gauge reads 20 pounds per square inch gauge (psig) at sea level, what is the absolute pressure?

To determine the absolute pressure from a gauge pressure reading, it is important to understand the relationship between the two. Gauge pressure (psig) measures the pressure relative to atmospheric pressure, which is typically about 14.7 psi at sea level. Therefore, to convert gauge pressure to absolute pressure (psia), you must add the atmospheric pressure value to the gauge reading.

In this case, the gauge reads 20 psig, meaning it is 20 psi above atmospheric pressure. To find the absolute pressure, you add the atmospheric pressure (14.7 psi) to the gauge pressure (20 psi):

20 psig + 14.7 psi = 34.7 psia.

Thus, the absolute pressure is 34.7 psia, making this the correct answer. Understanding the conversion from gauge pressure to absolute pressure is crucial in HVAC/R applications, as many calculations related to system performance, fluid dynamics, and thermodynamic properties require absolute pressure values.