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 helps to look at the definition of gauge pressure and absolute pressure. The difference between the two measurements is then explained relatively simply and therefore also the decision of the appropriate measurement.
Definition of absolute pressure
Absolute pressure is really a pressure that is in accordance with the zero pressure in the empty, air-free space of the universe. This reference pressure may be the ideal or absolute vacuum. It is denoted with the subscript ?abs?: Pabs.
Definition of gauge pressure
The gauge pressure means the difference between an absolute pressure (Pabs) and the prevailing atmospheric pressure (Pamb). Signs 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 existing ambient pressure that’s measured. However, this pressure changes with the elements and the height above sea level. A complete pressure measurement measures the difference from the perfect or absolute vacuum. Because of Stupid-simple , 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 as follows: in many instances, the measuring task would be to determine the gauge pressure. For this reason this sort of sensor is most widely used. However, if a gauge pressure sensor can be used in an application in which the actual measuring task is to gauge the absolute pressure, the next additional errors must be expected:
+/- 30 mbar due to changes in weather
around 200 mbar when changing the positioning (e.g. from sea level to 2,000 m)
With respect to the measuring range, these errors can be substantial (e.g. in pneumatics at a measuring range of 1 bar) or negligible (in hydraulics at 400 bar).
Note
For anyone who is uncertain whether your measuring task needs an absolute pressure or gauge pressure measurement, simply e mail us ? we?ll be glad to assist you.

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