What is 0 psiG equivalent to in atmospheric pressure?

• A. 0.5 atm
• B. 1 atm
• C. 2 atm
• D. 3 atm

Answer: (B)

The measurement of pressure in psiG (pounds per square inch gauge) refers to the pressure relative to atmospheric pressure. When a gauge reads 0 psiG, it indicates that the pressure is equal to atmospheric pressure.

Atmospheric pressure at sea level is generally accepted as 1 atmosphere (atm), which is approximately 14.7 psi. Therefore, when the gauge reads 0 psiG, it signifies that the pressure being measured is equal to that of the surrounding atmosphere, which is 1 atm. This concept is critical in understanding how gauge pressures are measured and interpreted in various applications, including anesthesia machines.

The other values provided (0.5 atm, 2 atm, and 3 atm) would indicate pressures that are either below or above atmospheric pressure, which does not apply at the point where the gauge reads zero. Hence, 0 psiG is directly equivalent to 1 atm of atmospheric pressure.