Difference between gauge pressure and absolute pressure measurement

Again and again, we have been asked the question about 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 your two measurements is then explained relatively simply and thus also the choice of the correct 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 is denoted with the subscript ?abs?: ไดอะแฟรม .
Definition of gauge pressure
The gauge pressure is defined as the difference between a complete pressure (Pabs) and the prevailing atmospheric pressure (Pamb). It really is denoted with the subscript ?e?: Pe and is calculated the following: 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 always the difference from the existing ambient pressure that is measured. However, this pressure changes with the weather and the height above sea level. An absolute pressure measurement measures the difference from the ideal or absolute vacuum. This is exactly why this measurement is independent of environmental influences such as for example weather or altitude. Which measurement is currently the right one?
In practice, the two measurements can be differentiated as follows: in most cases, the measuring task is to determine the gauge pressure. This is exactly why this type of sensor is most widely used. However, if a gauge pressure sensor is used in an application where the actual measuring task is to gauge the absolute pressure, the next additional errors must be expected:
+/- 30 mbar caused by changes in weather
around 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
Should you be uncertain whether your measuring task needs an absolute pressure or gauge pressure measurement, simply e mail us ? we?ll be glad to work with you.

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