Pressure measurement and monitoring is an essential part of modern industrial processes. The pressure to be measured can be defined as different categories based on measurement reference. While measuring gauge pressure can be sufficient for most industrial applications, sometimes use an instrument that displays absolute pressure is necessary.
Absolute Pressure and Gauge Pressure
The globe’s atmosphere has weight and creates pressure itself. The amount of atmospheric pressure is also called ambient pressure, which varies around 101.325kPa (standard atmosphere) by altitude and weather conditions. The core difference of absolute pressure and gauge pressure lies in whether atmospheric pressure is included. The reference point of gauge pressure is atmospheric pressure while for absolute pressure it is vacuum environment where atmospheric pressure is not exist at all. Therefore the reading of absolute pressure actually shows the sum of atmospheric pressure and gauge pressure.
Pressure is usually measured by quantifying the deformation of a sensing element, where one side of the element is exposed to a reference and the other side is in contact with the process medium. For gauge pressure sensor, the side of diaphragm not in contact with the medium is vented to ambient pressure, providing a gauge pressure reading which is actually the pressure difference between the process and atmospheric pressure. With absolute pressure sensor, the diaphragm is exposed to an absolute vacuum chamber that is permanently sealed. Since sealed vacuum is used as the reference point, diaphragm deformation is not impacted by atmosphere.
Since industrial facilities often share the same elevation and their pressure applications are not affected by changes in atmospheric pressure, standard gauge pressure measurement is accurate enough for most processes. However, specialized situations call for absolute pressure, which are independent of fluctuations in atmospheric pressure. Absolute pressure transmitters are frequently seen in the fields of chemical processing, aviation, HVAC, typically owing to following common reasons:
- ✦ The process requires maintaining a vacuum or extremely low pressure state, necessitating absolute pressure measurement to held a precise value.
- ✦ The process rely on sublimation or outgassing and need to know the absolute force left in the chamber to determine when the process is complete.
- ✦ The vessel is operated under a vacuum to lower medium boiling point and precise control of absolute pressure is crucial.
- ✦ During engine test,the pressure in the intake manifold is often below atmospheric pressure and is required for calculation of air mass.
Shanghai Wangyuan is an experienced manufacturer and supplier of measurement instruments for over 20 years of. Wangyuan offers a comprehensive range of pressure transmitters for measurement solutions including absolute, gauge as well as differential pressure. If you have any question regarding the selection of absolute pressure transmitters, please feel free to get in touch with us.
Post time: Feb-27-2026