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Optomax Industrial Range of Liquid Level Switches

The Optomax Industrial range of liquid level switches were designed to offer industrial supply voltages and outputs that can directly drive higher power loads.

The microcontroller based sensor is solid state, incorporating an infra-red LED and phototransistor which are optically coupled by the tip when the sensor is in air. When the sensing tip is immersed in liquid, the infra-red light escapes making the output change state. The sensor can detect the presence or absence of almost any liquid type; oil or water based. It is insensitive to ambient light and is not affected by foam when in air or by small bubbles when in liquid.

A range of N and P type output configurations can sink or source up to 1A at supply voltage ranges from 4.5 to 15.4Vdc or 8 to 30Vdc and can be configured to output a high or low signal in either a wet or dry state. Options for connecting to inductive loads or digital interfaces are also available.

With housing threads suitable for external sensor mounting and for use in two operating temperature ranges; Standard (-25 to 80°C) or Extended (-40 to 125°C).

Available in two chemically resistant housing materials, Polysulfone, the standard choice for most applications, or Trogamid, which is typically used in food and beverage applications.

The Optomax Industrial range of liquid level switches are built to the highest quality standards and are not only highly accurate but they also have a good lifespan.


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Part Numbering Guide


Supply Voltage (Vs)

Supply Voltage

Output Sink and Source Current (lout)

Operating Temperatures

Storage Temperatures

Housing Material

Sensor Termination

Operating Pressure

4.5 to 5.5Vdc or
8 to 30Vdc

2.5mA max. (Vs = 4.5 to 15.4Vdc) or
7.5mA max. (Vs = 8 to 30 Vdc)


Standard: -25⁰C to +80⁰C
Extended: -40⁰C to +125⁰C

Standard: -30⁰C to +85⁰C
Extended: -40⁰C to +125⁰C

Polysulfone (standard option) or Trogamid

20AWG, 250mm PTFE wires, 8mm tinned

0 to 7 bar


Optomax Industrial Range of Liquid Level Switches Drawing


Output Voltage (Vout)

Output High

Output Low

Output Voltage (Vout)

Output High

Output Low

lout = 1A Vs = 4.5 to 15.4Vdc

Vout = Vs - 1.5V max

Vout = 0V + 0.5V max

lout = 1A Vs = 8 to 30Vdc

Vout = Vs - 1.8V max

Vout = 0V + 0.7V max


Liquid Level Wiring Diagram









  • Designed for applications requiring a robust metal housing and a wide operating temperature range
  • Reverse polarity, ESD, transient over-voltage and short circuit protected
  • Wide supply voltage ranges
  • N and P type output configurations, capable of sinking or sourcing up to 200mA, can directly drive small loads
  • Standard and extended temperature ranges available
  • Stainless steel housing with simex glass sensing tip
  • Choice of terminations
  • Very high operating pressure
  • LED output indication


  • Solid state so no moving parts to cause unreliability
  • Fast response time
  • Repeatable switching point
  • Very robust construction permitting use in a wide range of demanding applications
  • Compatible with most fluids and chemicals
  • SST Sensing’s highest operating temperature liquid level switch


Liquid sensing 001_450

When in air the infrared light is reflected back to the detector


Liquid sensing 002_450

When in liquid the infrared light is refracted and the output switches

  • This field is for validation purposes and should be left unchanged.