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 can help to look at this is of gauge pressure and absolute pressure. The difference between your two measurements is then explained relatively simply and therefore also the choice of the correct 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. This reference pressure is 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). It really is denoted with the subscript ?e?: Pe and is calculated as follows: Pe = Pabs ? Pamb.
Suck between the two measurements is relatively easily clarified: in a gauge pressure measurement, it is usually the difference from the current 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. This is why this measurement is independent of environmental influences such as weather or altitude. Which measurement is now the right one?
In Interesting , the two measurements could be differentiated as follows: typically, the measuring task is to determine the gauge pressure. This is exactly why this sort of sensor is hottest. However, if a gauge pressure sensor can be used in an application where the actual measuring task is to measure the absolute pressure, the following 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)
Depending 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
For anyone who is uncertain whether your measuring task needs an absolute pressure or gauge pressure measurement, simply contact us ? we?ll be glad to work with you.