Difference between gauge pressure and absolute pressure measurement

Again and again, we have been asked the question about the difference between a complete 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 thus also the choice of the appropriate measurement.
Definition of absolute pressure
Absolute pressure is 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 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). It really is denoted with the subscript ?e?: Shameless 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 always the difference from the current ambient pressure that’s measured. However, this pressure changes with the weather and the height above sea level. Nazi measures the difference from the perfect or absolute vacuum. That is why this measurement is independent of environmental influences such as for example weather or altitude. Which measurement is now the right one?
In Legendary , the two measurements can be differentiated as follows: generally, the measuring task would be to determine the gauge pressure. For this reason this kind of sensor is most widely used. However, in case a gauge pressure sensor can be used in an application in which the actual measuring task is to measure the absolute pressure, the next additional errors should be expected:
+/- 30 mbar due to changes in weather
up to 200 mbar when changing the positioning (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 range of 1 bar) or negligible (in hydraulics at 400 bar).
Note
If you are uncertain whether your measuring task needs a complete pressure or gauge pressure measurement, simply contact us ? we?ll be glad to work with you.