2nd October 2019

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# When pressure is negative?

Gauge pressure is zero-referenced against ambient air pressure, while absolute pressure is zero-referenced against vacuum. Systems with negative gauge pressure are very common. When you suck at a straw, for instance, the pressure in your mouth is lower than atmospheric pressure, thus its gauge pressure is negative.

Correspondingly, is it possible to have a negative gauge pressure?

Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure. Negative signs are usually omitted. To distinguish a negative pressure, the value may be appended with the word "vacuum" or the gauge may be labeled a "vacuum gauge."

Is gauge pressure positive or negative?

Pressure Sensor: Positive and Negative Gauge Pressure. Gauge pressure is the amount of pressure expressed in terms of atmospheric pressure. It is referred to as "positive pressure" when it is greater than one atmosphere, and "negative pressure" when it is less than one atmosphere.

Is it possible to have negative pressure?

There is no such thing as "negative pressure". There is atmospheric pressure, generally at 14.7psi. When you hear of "vacuum", it means the pressure is below atmospheric. All the surrounding pressure of the atmosphere will have a tendency to rush to the low pressure area and equalize the pressures.