Selecting the right pressure switch for you

Pressure switches are commonly used piece of equipment across a wide range of industries, and for a wide range of applications. As one of Western Australia’s leading supplier of pressure instrumentation products, DG Instruments understands that the paradox of choice in this market can make selecting the right pressure switch more difficult than it should be – which is why we’ve provided this information to help you chose the right pressure switch for your application:

Pressure Switches

A pressure switch’s basic function is to detect changes in pressure, and convert that into an electrical signal function – typically by switching something on/off. Though pressure switches can come in a number of different styles and types, choosing the correct pressure switch for your application is quite general once you have a basic understanding of the function.

Set Point & Deadband

Set Point (SP) – Set point is the desired value reached at which the pressure switch changes electrical states, triggering the switch. This value can be a rising figure or falling figure, and the switch that is triggered when set point is achieved can be wired to perform a number of functions – generally to open (turn OFF) or close (turn ON), set off an alarm or signal, or shut equipment down.

For best performance and longevity, a switch’s set point value should fall between the mid 50% of the pressure switch range. The set point can generally be adjusted internally or externally through the adjustment of a reference dial or use of an electronic programmer.

Deadband (DB) – Deadband refers to the on-off differential required to reset the switch, and may be a fixed or adjustable figure, depending on the specific application requirements of the switch.


Important Factors to Consider

System Pressure

Being aware of your normal and maximum system pressure is an important factor in helping select a pressure switch with appropriate operating parameters – with the relationship between set point and system pressure having a direct and significant effect on the performance and life of your switch. Once your Set Point is established, other factors such as vacuum and surge pressure could affect switch operation, and should be taken in to consideration.

Pressure Switch Mounting

Pressure switches can be mounted in a number of different ways depending on application. The unit could installed directly to the process using a mating fitting pipe thread taper, straight threaded connection, flush mount connection or sanitary connection; the switch may be mounted directly to the process line using threaded connection, a manifold or flange; or the enclosure could be bolted to a mounting plate or other plane to secure it. Factors such as heavy vibration should be considered when mounting.

Process Environment

Knowing what type of environment the pressure switch is going to be installed is a huge factor to consider – whether that be a hazardous location, indoors, outdoors, exposed to elements, ambient temperatures, or inside a control panel… just to name a few. Thus, choosing the correct enclosure type is an important consideration, with many enclosure types conforming to various industry and third-party approved standards.

Of course, we understand that a lot of this information requires a certain degree of mechanical, electrical or industry-specific knowledge… so if you’re still as confused as you were previously (or more so!) about what pressure switch is right for you – do not despair!

At DG Instruments, we have the knowledge and experience to happily provide expert advice, information or answer questions regarding all our Precision Instrumentation Products. With over 30 years combined industry experience, we can also offer efficient on-site and emergency servicing – so feel free to contact us today with any further enquiries!

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