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psig question

psig question

psig question

(OP)
can some one tell me the relationship between Hg and negative pisg

RE: psig question

1 Atmosphere = 14.7 PSI
14.7 PSI = 760mm(29.92")of mercury Hg.

A pressure gauge with a scale of 0-20 PSI is actually reading 14.7 PSI(absolute) when at zero because its measuring the atmospheric pressure. The 0-20 scale is the guage pressure in PSIG.

Less than 14.7 PSI, 760mm HG , 1 BAR is a vacuum.

A guage showing 4.7 negative PSI is showing 10PSI absolute pressure which is equal to 524.13mm Hg.

Hg is a measurement of a column of mercury in a positive or negative pressure.

Basically what I am trying to say, rather badly, is that absolte pressure is a reference to absolute zero pressure...outerspace...no pressure at all. Gauge pressures are referenced to the zero point on the gauge which is 14.7 PSI above absolute pressure.   

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