Pressure Measuring Instruments

The Latest Pressure Measuring Instruments from Endress+Hauser

Pressure is often described as the amount of force, created by the compression of a medium, on a particular point. ‘Point’ is a misleading term as when a force comes up against an impermeable surface plane, the dynamic load spreads over the whole plane in a balanced method.

Because of the abovementioned spread, the measurement of pressure is, therefore, subject to the amount of compression received by the medium as well as the size of the plane that it interacts with. Enter the diversity of instruments that can measure pressure along with the huge advances in their design.

The Main Types of Pressure that are Commonly Measured

  • When a gas medium or a liquid medium is the source of the force then the pressure type is called fluid pressure.
  • When the surrounding air pressure is the source fluid the pressure type is called atmospheric pressure.
  • When measuring pressure, the surface area that is being measured is defined as the unit area, labeled kPa, MPa, PSI or bar.
  • The absolute pressure measurement is the force measured per unit area where the fluid meets the surface versus absolute zero (vacuum).
  • The discrepancy between the pressures of absolute and atmospheric gives you a gauge pressure measurement.

Atmospheric pressure is greatly affected by altitude, weather and surrounding pressure.

The History of Instruments to Measure Pressure

At around about the 1850s, “equipment” started appearing with the aim of standardising and simplifying the area of measurement. One of the first on the scene was the Bourdon tube. This revolutionary device still exists today and is a good choice for measuring static pressure without much redesign of its original concept.

The Bourdon tube consists of a metal tube that stops short of being a full circle. It is open to incoming pressure at one point and connected to a linkage, pivot and toothed quadrant which move the needle to a correlating pressure reading.

History of Pressure Measuring Instruments

Bourdon Tube – a helical-shaped tube that is used to move a slider of a potentiometer to give a display or electrical output related to the pressure applied