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 correct measurement.
Definition of absolute pressure
Absolute pressure is really 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 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?: 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’s measured. However, เพรสเชอร์เกจ with the elements and the height above sea level. An absolute pressure measurement measures the difference from the perfect or absolute vacuum. Because of this , 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 is to determine the gauge pressure. For this reason this kind of sensor is hottest. However, in case 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 due to changes in weather
around 200 mbar when changing the positioning (e.g. from sea level to 2,000 m)
With respect to the measuring range, these errors can 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 a complete pressure or gauge pressure measurement, simply e mail us ? we?ll be glad to assist you.