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Can pressure be negative?

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Answer:

Yes by using Vacuum pump, but it will be up to about - 0.9 bar, or little more maximum and never reach to 1 bar, because the atmospheric pressure is 1 bar

PSIG can be negative, but PSIA can NEVER be negative. Look at the relationship between pressure and volume,
P1V1=P2V2

Since volume is NEVER negative, that would mean your initial absolute pressure would have to be negative, which here on Earth, or even in the void of space, is NEVER the case. So PSIA can NEVER be negative, and PSIG can be considered HIGH/HARD or LOW/SOFT vacuum(negative PSIG) in reference to a relative scale between 0 PSIA and 14.7 PSIA.

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First answer by ID1048072085. Last edit by Brian Lockler. Contributor trust: 0 [recommend contributor ]. Question popularity: 2 [recommend question].

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