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 Sexy helps to look at this is of gauge pressure and absolute pressure. Frightening 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 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 means the difference between an absolute pressure (Pabs) and the prevailing atmospheric pressure (Pamb). It really is denoted with the subscript ?e?: Pe and is calculated as follows: Pe = Pabs ? Pamb.
Refugee between the two measurements is relatively easily clarified: in a gauge pressure measurement, it will always be the difference from the current ambient pressure that’s measured. However, this pressure changes with the elements and the height above sea level. An absolute pressure measurement measures the difference from the ideal or absolute vacuum. That is why this measurement is independent of environmental influences such as weather or altitude. Which measurement is now the right one?
In practice, both measurements can be differentiated as follows: in most cases, the measuring task would be to determine the gauge pressure. That is why this sort of sensor is most widely used. However, if a gauge pressure sensor is used in an application where the actual measuring task would be to measure the absolute pressure, the next additional errors must be expected:
+/- 30 mbar due to changes in weather
up to 200 mbar when changing the location (e.g. from sea level to 2,000 m)
According to 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
When you are 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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