What psig is considered atmospheric pressure?

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What psig is considered atmospheric pressure?

Gauge pressure shows how much pressure exists above the surrounding atmospheric pressure. When something is at atmospheric pressure, there is no extra pressure above what the air is already exerting, so the gauge reads zero. At sea level, atmospheric pressure is about 14.7 psi absolute, but that is psia, not psig. Since psig measures pressure relative to ambient air, atmospheric pressure corresponds to 0 psig. If the pressure were higher than ambient, you’d read a positive psig; if lower, a negative psig. So the value that represents atmospheric pressure on a gauge is zero psig.

Gauge pressure shows how much pressure exists above the surrounding atmospheric pressure. When something is at atmospheric pressure, there is no extra pressure above what the air is already exerting, so the gauge reads zero. At sea level, atmospheric pressure is about 14.7 psi absolute, but that is psia, not psig. Since psig measures pressure relative to ambient air, atmospheric pressure corresponds to 0 psig. If the pressure were higher than ambient, you’d read a positive psig; if lower, a negative psig. So the value that represents atmospheric pressure on a gauge is zero psig.

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