How does gauge pressure relate to absolute pressure?

• A. Gauge pressure is higher than absolute pressure
• B. Gauge pressure is equal to absolute pressure
• C. Gauge pressure is 1 bar more than absolute pressure
• D. Gauge pressure is 1 bar less than absolute pressure

Answer: (D)

Gauge pressure is defined as the pressure measured relative to the ambient atmospheric pressure. This means that gauge pressure does not account for atmospheric pressure, which is typically about 1 bar or 14.7 psi at sea level.

Absolute pressure, on the other hand, includes atmospheric pressure in its calculations. Therefore, absolute pressure is equal to the gauge pressure plus the atmospheric pressure.

When considering the relationship between gauge pressure and absolute pressure, it can be understood that the gauge pressure reads lower than absolute pressure by the value of atmospheric pressure. Consequently, if the atmospheric pressure is around 1 bar, then gauge pressure will indeed be 1 bar less than absolute pressure. This relationship is fundamental in fields such as refrigeration, HVAC, and any application where pressure measurements are critical, as it ensures clarity in interpreting pressure readings in different contexts.