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Old 03-11-2013, 09:44 AM
dvsgene dvsgene is offline
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I take it as the former too as that weblink you provided also states:

Quote:
The above form works if you are measuring differential pressure, such as the difference in psi between two points. It also gives the correct answer for absolute pressure, assuming you are measuring psia, which is the pressure relative to absolute zero vacuum
I presume the typical dial guage is calibrated to zero vacuum/pressure at a zero reading.
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