Difference between gauge pressure and absolute pressure measurement

Again and again, we have been asked the question concerning the difference between an absolute pressure measurement and a gauge pressure measurement. To answer this question it can help to look at this is of gauge pressure and absolute pressure. The difference between your two measurements is then explained relatively simply and thus also the choice of the appropriate measurement.
Definition of absolute pressure
Absolute pressure is a pressure that is relative to the zero pressure in the empty, air-free space of the universe. This reference pressure is the ideal or absolute vacuum. It really is denoted with the subscript ?abs?: Pabs.
Definition of gauge pressure
The gauge pressure is defined as the difference between an absolute pressure (Pabs) and the prevailing atmospheric pressure (Pamb). Colorful is denoted with the subscript ?e?: Pe and is calculated the following: Pe = Pabs ? Pamb.
Absolute vs gauge pressure measurement
The difference between your two measurements is relatively easily clarified: in a gauge pressure measurement, it is usually the difference from the current ambient pressure that is measured. However, this pressure changes with the elements and the height above sea level. An absolute pressure measurement measures the difference from the perfect or absolute vacuum. Because of this , this measurement is independent of environmental influences such as weather or altitude. Which measurement is now the right one?
In practice, the two measurements could be differentiated as follows: usually, the measuring task is to determine the gauge pressure. Because of this , this type of sensor is most widely used. However, if a gauge pressure sensor is used in an application in which the actual measuring task is to measure the absolute pressure, the following additional errors should be expected:
+/- 30 mbar caused by changes in weather
up to 200 mbar when changing the location (e.g. from sea level to 2,000 m)
Based on the measuring range, these errors could be substantial (e.g. in pneumatics at a measuring selection of 1 bar) or negligible (in hydraulics at 400 bar).
Note
For anyone who is uncertain whether your measuring task needs a complete pressure or gauge pressure measurement, simply contact us ? we?ll be glad to assist you.

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