Cross Connection Practice Exam

An absolute pressure of 25 psia, at sea level, is equal to approximately what gauge pressure?

1. 5 psig

2. 10 psig

3. 15 psig

4. 20 psig

The correct answer is: 10 psig

To determine the gauge pressure from the absolute pressure, one needs to understand the relationship between absolute pressure and gauge pressure. Absolute pressure is measured relative to a perfect vacuum, while gauge pressure is measured relative to atmospheric pressure. At sea level, the atmospheric pressure is approximately 14.7 psi. To find the gauge pressure, you subtract the atmospheric pressure from the absolute pressure. In this case, starting with an absolute pressure of 25 psia: 1. Subtract the atmospheric pressure from the absolute pressure: 25 psia - 14.7 psi = 10.3 psig. Since gauge pressure is often rounded off, this value would typically be taken as approximately 10 psig. This calculation shows that the absolute pressure of 25 psia translates to a gauge pressure around 10 psig, which aligns with the correct answer.