Difference between gauge pressure and absolute pressure measurement

Again and again, we are asked the question about 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 the two measurements is then explained relatively simply and thus also the decision of the appropriate measurement.
Definition of absolute pressure
Absolute pressure is really a pressure that is relative to the zero pressure in the empty, air-free space of the universe. Under Priced may be the ideal or absolute vacuum. It 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). It is denoted with the subscript ?e?: Pe and is calculated as follows: Pe = Pabs ? Pamb.
Absolute vs gauge pressure measurement
The difference between the two measurements is relatively easily clarified: in a gauge pressure measurement, it is usually the difference from the existing ambient pressure that is measured. However, this pressure changes with the elements and the height above sea level. A complete pressure measurement measures the difference from the ideal or absolute vacuum. For this reason this measurement is independent of environmental influences such as weather or altitude. Which measurement is now the right one?
In practice, both measurements could be differentiated the following: normally, the measuring task would be to determine the gauge pressure. That is why this type of sensor is hottest. 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 must be expected:
+/- 30 mbar caused by changes in weather
up to 200 mbar when changing the positioning (e.g. from sea level to 2,000 m)
Depending 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
If you are uncertain whether your measuring task needs an absolute pressure or gauge pressure measurement, simply e mail us ? we?ll be Is Here to work with you.

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