Transducers, Pressure Switches And Flow Switches – How Do We Tell The Difference?

It is a common mistake within the world of electrical engineering and plumbing to get confused between transducers and pressure switches. Whilst both of these engineering devices are classified as sensors, they have significantly different functions and safety features, and therefore getting them mixed up is not desirable.

So how exactly can we tell the difference between transducers and pressure switches?

Pressure switches
Compared to transducers, pressures switches are considerably more simplistic, traditional and less sophisticated. As its name suggests, pressure switches are simply controls that can be moved into one of two positions – open or closed – of which the pressure of the gas is connected.

An engineer is usually forced to think about pressure switches when a hydraulic or pneumatic system fails, when designing an in-house system, or when he/she has purchased equipment or a system that contains a pressure switch.

Whilst be such a simplistic component of engineering pressure switches rarely fail, the downside of pressure switches is that they are not that accurate, as the specifications range from just 5% of fill scale to 10% of full scale.

Transducers
By comparison, transducers are much more intricate and sophisticated and are increasingly being used to replace the much more ‘old school’ and traditional pressure switches.

Transducers are effectively any device that converts energy from one form into another, usually by converting input energy into output energy.

Similar to a pressure switch, transducers are connected to a gas pipeline. Transducers must always work in juxtaposition with a circuit board.  The pressure of the gas is held against a metal diaphragm, which moves according to the rise and fall of the gas pressure. The amount of deflection is measured by the transducer; the information is collected and then transferred to a circuit board in milli-volts.

Flow switches
Flow switches are extremely common components in electrical devices and are used in many applications in a whole range of industries. In its simplest form, a flow switch allows for direct flow sensing that will detect if the gas or liquid that is flowing through the switch.

There is another flow switch installation known as indirect flow sensing, which essentially involves installing a flow switch in a bypass line so that only a portion of the system’s flow passes through the line. In detecting any rate of flow within the pressure rating of a unit, indirect flow sensing significantly expands the range of possible applications for a flow switch.

Blogger Jessica Wade is a blogger who wrote this article of behalf of appeng.co.uk.