Making the Optical Liquid Level Switch with the New SICK GRF18S Range

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SICK, one of the world leaders in the design and manufacture of innovative and advanced sensory technology has discontinued the MHF15 range of Optical Liquid Level Switches and replaced them with a direct equivalent – the GRF18S Range.

The Ideal Optical Liquid Level Switch

Just as simple to use and equally as compact and versatile as its predecessor this replacement range has the added advantage of 2 built-in LEDs that indicate the switching status of the sensor for easy level detection of water. Based on SICK photoelectric proximity sensor technology, the GRF18S range offers fast, issue-free commissioning and they do not require medium calibration, which ultimately leads to reductions in the costs of commissioning and maintenance. Much like its predecessor the GRF18S range is ideally suited for water-based media.

Measuring the Level Benefits

  • Small liquid level switch ideal for limited spaces
  • Easy to commission
  • Reduced maintenance, no calibration
  • Outputs available as PNP or NPN
  • FDA Compliant, UL

Optical Liquid Level Switch

Who is replacing who?

GRF18S-E234LV replaces the MHF15-21NG1TSM

  • Output signal 1 x NPN
  • Switching mode NO


GRF18S-N234LV replaces the MHF15-21NG1NSM

  • Output signal 1 x NPN
  • Switching mode NC


GRF18S-F234LV replaces the MHF15-21NG1HSM

  • Output signal 1 x NPN
  • Switching mode NO


GRF18S-P234LV replaces the MHF15-21NG1PSM

  • Output signal 1 x PNP
  • Switching mode NC


GRF18S Range – Liquid Level Switch Common Features:

  • 2 x LEDs for status monitoring
  • Process pressure -0.5 bar to 16 bar
  • Operating voltage 10 Vdc to 30 Vdc
  • Connection – M12 round connector – 4 pin
  • Protection rating IP67 and IP69
  • Process Connection G ½
  • Stainless steel construction with Polysulfone Apex
  • Operating temperature range -25 to +55 °C


View the Range


Kempston Controls, as a supplier partner for SICK stocks an impressive range of sensory and process control devices designed to suit whatever your application needs are. Contact our Sales team at or call us on +44 (0) 1933 411 411.


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Kempston Controls

Kempston Controls is committed to finding you the ideal solution for your application. Call us today on +44 (0) 1933 411 411, email us at, or alternatively contact us here, we will be happy to help.

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