Optical Liquid Level Switches That Can Be Used in Almost Any Liquid

SST’s liquid level switches are available in various housing materials; Polysulfone, Trogamid®, Tritan™, Stainless Steel and Glass. Each designed to offer different attributes and abilities in order to operate in a large range of liquid types.

Preventing expensive damage, flooding or run dry operation in liquid pumping systems. In level control systems such as monitoring fuel and hydraulic oil tanks in off-road construction vehicles. Protecting valuable equipment and preventing service interruption by detecting when liquid is somewhere it shouldn’t be, such as inside outdoor telecommunication enclosures. These are just a few of the common applications where SST Sensing’s liquid level switches are used with great success.

Designed and manufactured by SST in Scotland, the cost effective, single point optical liquid level switches are the product of choice when reliability, durability and fast response are required.

The liquid level switches are available in a wide range of sizes, materials, housing styles and electrical connections in order to meet the demands of varied and diverse customer applications. The robust point level switches detect the presence or absence of almost any liquid; oil or water based and, depending on the application, can be exposed to extreme environmental conditions.

The type of housing materials offered by SST are therefore critical and depend entirely on how compatible the liquid level switches are to the environmental conditions they will be exposed to. SST’s liquid level switches are available in Polysulfone, for use (amongst many others) in diesel, oil, methanol; Trogamid®, for other hostile liquids such as acetone, petroleum oil approved for direct food contact in the European Union; Tritan™ which is NSF and FDA approved in the USA for medical and food use.   Finally sensors with stainless steel housings and glass sensing tips are ideal for use in extremely aggressive chemicals which would damage plastics and where operation in extreme, high temperature environments is necessary.

The operating principle doesn’t change regardless of which housing material the customer selects. When the switch is in air, the infrared light from an infra-red LED inside the sensor tip is internally reflected back to a detector. When in liquid, the infrared light is refracted out of the sensor tip, causing less energy to reach the detector. It’s as simple as that!

Optical Liquid Level SwitchesSST’s liquid level switches are unlike other liquid detection technologies, they have a long operating life, low sensitivity to ambient light and are not affected by foam when in air, or small bubbles when in liquid. Used as an alternative to float switches but without the worry of unreliable moving parts, they are completely solid state. They are compact, only protrude a small distance into the application and are able to instantaneously detect very small amounts of liquid. Their ability to function over a wide range of operating temperatures and harsh liquid media for long periods of time make SST’s optical liquid level switches a versatile and reliable solution when detecting the presence or absence of liquid.

SST understands that customer needs vary and can be very specific. If our standard range of liquid level switches do not meet your specification, we offer customisation of any of our sensor products in order to meet your precise requirements. Whether that be by adding or modifying electronics and software, changing outputs, adapting housing or thread styles, adding cabling, connectors or environmental protection, SST will consider all options to ensure our customers’ requirements have been met.

For more information on SST’s liquid level switches, please Ask the Expert! 

Need Help? Ask the expert

Call us today on +44 (0)1236 459 020

Optomax basic Liquid Level Switch

Optomax Digital

Ideal for applications with restricted space that require a miniature, low power, low cost sensing solution.


Industrial LL

Optomax Industrial

Designed to offer industrial supply voltages and outputs that can directly drive higher power loads.

Optomax Industrial Glass (Coming Soon)

Optomax Industrial Glass

Designed to operate in aggressive environments due to their stainless steel construction and glass sensing tip.


LLHP Range of Liquid Level Switches


The LLHP range of liquid level switches offer larger mounting threads and robust stainless steel housings that can survive in aggressive environments.

Get in touch

Our Engineers have over 60 years combined experience in the sensor industry. To ask a question or get a quote, please contact us

Request a Quote

Find out more

Ask our experts

Ask the Expert