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What are the types of pressure sensor?

Pressure sensors are used in a vast array of applications, from medical environments to safety-critical pressure measurement in hydraulic brake systems. In industrial applications where processing takes place, it is often important to measure pressure accurately to control the quality of the final product, and sometimes to control the process itself. The market has various types of pressure sensors available, not least because they are used in so many different ways, however, within this article, we will take a look at some of the variables that are accounted for by different types of pressure sensors and the factors to consider when selecting one.

What different types of pressure are there?

Starting with the very basic principles, pressure is the perpendicular force applied to an object over the surface area of the object. Pressure = Force/Area. PSI, for instance, is pounds per square inch. Or a Pascal, which is one newton per square metre. There are three different types of pressure:

Gauge pressure: this is the most common type of pressure when dealing with engineering applications. Gauge pressure is the difference between a given pressure and atmospheric pressure. A positive overpressure is referred to when the absolute pressure is greater than the atmospheric pressure. If the measured gauge pressure is negative, it is called under pressure or partial vacuum.

Absolute pressure: this is the point above a perfect vacuum. Usually, it is the sum of gauge pressure plus atmospheric pressure.

Differential pressure: this is the difference between two points when neither is known and neither is a perfect vacuum.

All other ‘types’ of pressure (e.g. hydrostatic, negative, deflagration) are merely one of the options above with a name directly referencing the context of the pressure.

What pressure sensors are available?

Types of pressure sensors vary widely, however they can generally be categorised by the type of pressure (as outlined above), combined with the method of sensing, the output signal type and the media that they are measuring. Looking at each of those in more detail:

Sensing method: the sensor technique has a simple aim, to translate the pressure applied on the sensor mechanism into an electric signal as an output. Types of sensor options can include resistive, capacitive, resonant, piezoelectric, optical and MEMS. The sensor method used can affect accuracy, reliability, measurement range and whether it is appropriate for the operating environment.  

Output signals: these are generally either transmitters, which create an output current or transducers, which create an output voltage which is variable in accordance with the experienced pressure.

Media type: the operating environment will impact the type of pressure sensor that you choose. For example, if your pressure sensor will be working with corrosive media or within clean in place systems or other hygienic environments, you will need to carefully select a solution that not only maintains the stringent hygiene levels employed but which won’t be damaged by the solutions that it is measuring. Other considerations in terms of media include whether the flow is air, gas, liquid, hydraulic or pneumatic. 

There are so many types of pressure sensors available that there is likely one on the market which is perfect for your application. However, if you are finding the array of options daunting, or would like advice in selecting the appropriate sensor for your type of pressure sensing requirement, why not get in touch? Call us on 01254 390555 or email [email protected]

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