A zero psi reading on most pressure gauge is actually blank psi pressure at sea level

• A. 0
• B. 7.5
• C. 14.7
• D. -14.7

Answer: (C)

Gauge pressure is measured relative to the surrounding air. A reading of zero on a typical pressure gauge means the pressure inside equals the ambient atmospheric pressure. At sea level, atmospheric pressure is about 14.7 psi, so a zero gauge reading corresponds to roughly 14.7 psi of absolute pressure (psia). The other numbers don’t match this relationship to atmospheric pressure: they would imply inside pressure that’s either higher than ambient, lower than ambient, or vacuum, none of which is what a zero gauge reading represents.