Liquid Level Sensors

PST design, test and manufacture over 300,000 sensors a year.

We have the widest range of optical liquid level detection sensors available for any oil/ water-based liquid, reliably detecting the absence or presence of liquids in an application where status is critical.

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  • In many applications, people need to detect the presence or absence of liquid. SST’s liquid level switches use optical characteristics of liquids to determine if a liquid is there or not. A vast range of process connections, materials, housing styles, outputs and electrical connections are available to meet your needs.


  • Optical level switches provide precise monitoring of liquid levels, offering repeatable long life switching and control. The ability to detect from 1mm of liquid touching or leaving the sensor to trigger the switching output provides fast accurate control.

  • Optical sensors are versatile and can be used with a wide range of liquids, including clean and clear liquids, as well as those with suspended particles or bubbles. They are suitable for applications across various industries, from pharmaceuticals to food and beverage production.

  • Yes we offer a range of Intrinsically Safe level sensors for use with potentially hazardous liquids.

  • Optical sensors offer sub second response times, providing real-time data on liquid levels for quick decision-making and process control. This fast response is particularly beneficial in dynamic environments where liquid levels fluctuate frequently. Optional firmware variants allow for sloshing liquids and prevent false indications.

  • Optical sensors typically require minimal maintenance compared to other sensor types. With no moving parts to wear out or mechanical components to adjust, optical sensors offer reliable long-term operation with little to no maintenance required.

  • Optical level switches are often easy to install and integrate into existing systems. They can be mounted internally or externally to the tank or vessel, eliminating the need for complex installation procedures or modifications to the container.

  • Optical level sensors come in a wide range of housings to make them compatible to most acidic or alkaline liquids as well as hydrocarbon or plant based oils. With versions suitable for drinking water and pharmacopeia approvals our level switches are used in many industries.

  • Optical sensors can be easily integrated with remote monitoring and control systems, allowing for remote access to liquid level data. This capability enables operators to monitor liquid levels from a distance, enhancing efficiency and safety.

  • When in the air, the infrared light inside the sensor tip is reflected back to the detector. When in liquid, the infrared light is refracted out of the sensor tip, causing less energy to reach the detector.

Why choose PST?

  • Short lead times
  • Product reliability
  • Design engineers available for technical and product support
  • Datasheets, 2D drawings, 3D models and samples available
  • Every sensor is tested and inspected prior to shipment
  • Supply chain confidence
  • Product customization and branding
  • New developments driven by technology innovation and industry trends

Contact us or Request a Quote

We invite you to directly contact our experienced engineers to discuss your application needs.