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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.

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 100mA at a supply voltage range from 4.5 to 15.4 Vdc or 800mA at a supply voltage range from 10 to 45Vdc, all of which can be configured to output a high or low signal in either a wet or dry state.

The LLHP range of liquid level switches combine a robust stainless steel housing with a chemically resistant Polysulfone or Trogamid sensing tip and a selection of termination options. With large threads suitable for external mounting and for use in two operating temperature ranges; Standard (-25 to 80°C) or Extended (-40 to 125°C).


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Part Numbering Guide


Supply Voltages (Vs) 4.5 to 15.4Vdc
or 10 to 45Vdc
Supply Currents (Is) 15mA max. (Vs = 4.5 to 15.4Vdc)
or 35mA max. (Vs = 10 to 45Vdc)
Output Sink and Source Currents (Iout) 100mA (4.5 to 15.4Vdc)
or 800mA (10 to 45Vdc)
Operating Temperatures Standard: -25 to +80°C
or Extended: -40 to +125°C
Storage Temperatures Standard: -30 to +85°C
or Extended: -40 to +125°C
Housing Material Stainless steel with Polysulfone tip
Sensor Terminations Various, refer to datasheet
Operating Pressure 0 to 25 bar



Output Voltage (Vout): Iout = 100mA
Vs = 4.5 to 15.4Vdc
Output High Vout = Vs – 1.5V max
Output Low Vout = 0V + 0.5V max
Output Voltage (Vout): Iout = 800mA
Vs = 10 to 45Vdc
Output High Vout = Vs – 1.8V max
Output Low Vout = 0V + 0.7V max


Flying Leads/Cables

Wire Designation
Red Vs
Green/White Output*
Blue/Black 0V

*See part numbering guide for output type and logic




  • Designed for applications requiring a robust metal housing and larger threads for external mounting
  • Reverse polarity, ESD and transient over-voltage protected
  • Wide supply voltage ranges
  • N and P type output configurations, capable of sinking or sourcing up to 800mA, can directly drive loads
  • Standard and extended temperature ranges available
  • Stainless steel housing with Polysulfone sensing tip
  • Choice of terminations
  • High operating pressure


  • Solid state so no moving parts to cause unreliability
  • Fast response time
  • Repeatable switching point
  • Built-in output delays available on request for applications where sloshing causes intermittent switching
  • Very robust construction permitting use in a wide range of demanding applications
  • Compatible with most fluids and chemicals


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.