What is the difference between a pressure switch and a pressure transmitter?

Pressure switches and pressure transmitters are used in a wide variety of applications across an extensive list of industries. Quite often, both terms will be used interchangeably which can confuse individuals who are not familiar with them. So what is a pressure switch? What is the difference between a pressure switch and a pressure transmitter? Find out the answers in this informative guide from BM Engineering.

What is a pressure transmitter?

A pressure transmitter is a device that’s designed to measure the process pressure in liquids, fluids, or gases within an application. It then converts the value of the pressure into an equivalent voltage or current signal. They’re typically used to measure the pressure inside industrial machinery in order to alert users before an incident occurs.

A pressure transmitter is the preferred component for an application that measures the value of the pressure and transmits it to a PLC. When these signals are sent over long distances, there is no distortion in the results, which helps to make pressure transmitters very popular.

Where are pressure transmitters used?

You’re most likely to find pressure transmitters in filtration plants, chemical feeds, wastewater industries, food industries, pumping stations, and more. Due to their high demand, pressure transmitters are often quite customisable in pressure range, connection type, IP classification, accuracy, and much more.

What is a pressure switch?

A pressure switch is a device that opens or closes an electrical circuit when a specific pressure level has been reached. The pressure switch makes an electrical contact on either pressure rise or fall from a preset pressure level.

Where are pressure switches used?

Pressure switches are used within a wide range of industrial and residential applications, such as:

• Heating, ventilation and air conditioning (HVAC) systems – HVAC systems, air pumps, and similar systems, use pressure switches to monitor and control air pressure 
• Furnaces – Pressure switches within furnaces act as safety devices for industrial and residential purposes.
• Water pumps – Pressure switches are used in residential, commercial and agricultural applications to automatically regulate water flow.
• Boilers – Pressure switches are used in boilers, electric heaters and air compressors to measure vacuum or negative pressure in the system.

What’s the difference between a pressure switch and a pressure transmitter?

A common misconception about pressure switches and pressure transmitters is that they perform the same roles within any given application. However, there are major differences between the two components.

A pressure transmitter converts pressure into an electrical signal and transfers that to a PLC (Programmable Logic Controller). . A pressure switch, however, only triggers at a specific preset pressure, and, depending on the set pressure, a circuit can be engaged or disengaged.

Both devices measure pressure, but transmitters provide continuous feedback that is normally connected to a controller that monitors pressure. In comparison, a pressure switch doesn’t provide constant output and feedback and is much more similar to an on/off switch. A pressure switch is designed to open or close a circuit when pressure rises or falls, not transmit messages.

A pressure switch directly controls a fluid system and can operate without a power supply, but pressure transmitters just indicate pressure level with a continuous signal. They do not directly control a circuit and are used for more sophisticated applications like monitoring, predictive analysis, or process control.

Pressure transmitters are also much more expensive than pressure switches.

Pressure transmitters at BM Engineering

There are a number of high-quality pressure transmitters available at BM Engineering, such as the Bürkert Type 8750 and Bürkert Type 8323

The Type 8750 measures and controls gases using the differential pressure principle. It’s a reliable and robust system that consists of an ELEMENT continuous control valve, a Type 2301, with the compact process controller Type 8693 and two pressure transmitters, Type 8323. These components are supplied within an assembled system, including a special body.

The Type 8323 pressure transmitter has been developed to cover most industrial applications in the pressure measurement technology field. It’s suitable for different measurements with its high accuracy, robustness, compact design and flexibility.

For more information, and in-depth support and guidance, about our instrumentation range, please contact us today. You can speak to one of our knowledgeable technical experts here at BM Engineering by calling 0141 762 0657 or by emailing sales@bmengineering.co.uk.