What you have to consider when measuring pressure

Patrick Niedenführ
Patrick Niedenführ, November 2017

The choice of the right measuring method is decisive for your pressure measurement task. We explain the difference between absolute, gage and differential pressure and give application examples.

Absolute pressure

Absolute pressure sensors measure the pressure compared to a vacuum trapped in the sensor element.

Applications

  • Meteorological air pressure measurement
  • Vacuum packaging of food

Gage pressure

Gage pressure sensors measure the pressure in relation to the ambient air pressure. This means pressure changes in the environment affect the measured value. It can be measured pressures less than or greater than the ambient pressure. One also speaks of negative pressure and overpressure. Another important feature: Gage pressure sensors have only one pressure connection. The ambient pressure reaches the sensor through a small ventilation hole.

Applications

  • Tire pressure in relation to ambient pressure
  • Hydrostatic level measurement in ventilated tanks or open tanks
  • Medical aspirators that create a negative pressure

Differential pressure

Differential pressure sensors are similar to gage pressure sensors with one important difference: they can measure pressure not only relative to ambient air pressure, but relative to any other pressure. For this they need a second pressure connection. Common are hose, manifold or threaded connections.

Applications

  • Respiratory flow measurement in medical technology
  • Volume flow measurement in air conditioning
  • Filter monitoring

Now read our full article "Selecting the right pressure sensor" and …

1. … illustrate the difference between absolute, relative and differential pressure using a graphical representation.
2. … understand the structure of piezoresistive absolute, gage and differential pressure sensors.
3. … find out more about the different areas of application of pressure sensors.

White paper: Selection of the right pressure sensor

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In this blog, we write about applications and current topics in sensor technology.

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