What is Gauge Pressure?
Gauge pressure is pressure measured relative to the local atmospheric pressure, so it reads zero when open to air.
Gauge Pressure Explained
Most plant pressure gauges and transmitters read gauge pressure. The sensor has one side vented to the atmosphere, so changes in weather or altitude do not affect the zero.
Gauge pressure is negative under vacuum. For gas law calculations it must be converted to absolute pressure.
Gauge Pressure Formula
| pabs | absolute pressure |
| patm | local atmospheric pressure |
Calculators for Gauge Pressure
Frequently Asked Questions
What is Gauge Pressure?
Gauge pressure is pressure measured relative to the local atmospheric pressure, so it reads zero when open to air.
Why does a gauge pressure transmitter need a vent?
The reference side must see atmospheric pressure. A blocked or wet vent turns it into a sealed sensor that drifts with temperature and weather.
What is sealed gauge?
A sensor with the reference sealed at about one atmosphere. It is used where venting is impractical, but it does not follow changes in atmospheric pressure.
Learn more on the blog
Gauge pressure transmitter: working principle and applications
A practical guide on instrumentationblog.in with more detail on gauge pressure and how it is applied on real plants.
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