Again and again, we are asked the question concerning 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 decision of the appropriate measurement.
Dangerous 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 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 a complete pressure (Pabs) and the prevailing atmospheric pressure (Pamb). It really is denoted with the subscript ?e?: Gambling and is calculated as follows: 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 current ambient pressure that is measured. However, this pressure changes with the weather and the height above sea level. A complete pressure measurement measures the difference from the ideal or absolute vacuum. Because of this , this measurement is independent of environmental influences such as for example weather or altitude. Which measurement is currently the right one?
In practice, both measurements could be differentiated the following: generally, the measuring task is to determine the gauge pressure. For this reason this sort of sensor is hottest. However, if a gauge pressure sensor is used in an application in which the actual measuring task would be to gauge the absolute pressure, the next additional errors should be expected:
+/- 30 mbar due to changes in weather
around 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
Should you be uncertain whether your measuring task needs an absolute pressure or gauge pressure measurement, simply contact us ? we?ll be glad to assist you.