Before we take a closer look at the various types of pressure sensors available, we should make a quick note of the key definitions and differences between sensors, transducers, and transmitters.
Any pressure sensor device relies on changes in pressure causing a physical reaction in the sensing element. This change cannot be fed directly through to an attached circuit until it has been suitably translated and conditioned into a usable electronic signal.
The reason we need to differentiate between pressure sensors, pressure transducers and pressure transmitters is that they all incorporate a pressure sensing element, but each translates and conditions the output signal from that element in slightly different ways. Despite this, casual use of the generic term pressure sensor may refer to any of these three device types.
A true pressure sensor works on the principle whereby a physical reaction in the sensor module produces an output voltage. Further signal conditioning - such as calibration, amplification, and temperature compensation - must be handled separately before readings are considered reliable and stable.
The question ‘what is a pressure transducer?’ often follows from any explanation of a pressure sensor, which is understandable. Like pressure sensors, pressure transducers also produce an output voltage because of a physical reaction in the sensing element. The key difference is that some degree of signal conditioning is also handled by the transducer, allowing them to be transmitted a greater distance from the source.
A pressure transmitter works much like a transducer, except rather than a voltage reading, it will output a current signal across a low-impedance load (often somewhere in the 4-20mA standard industrial range).