Horizontal Float Switch Sensor (HFS)

The HFS sensor is designed for liquid detection in dry fiberglass tank interstitial spaces. These 2-wire, non-discriminating liquid sensors may be used with EVO™ 550 and EVO 500™ Automatic Tank Gauges (ATGs) as well as the S940 alarm console.



  • Fiberglass interstitial monitoring using a 2-wire sensor.
  • For dry fiberglass tank interstitial monitoring.
  • Highly reliable magnetic-float/reed-switch technology.
  • Chemical-resistant materials.



  • UL listed.


Each HFS comes with 25′ of oil-resistant cable. For fiberglass tanks, the HFS sensor is pulled into the interstitial space using a “fish” string wire. Optional installation kits are available which include a riser cap and other parts required to complete the installation.

Order Info

Model Description
FMP-HFS Horizontal float switch sensor (EVO™ 550 and EVO™ 5000)
TSP-HFS Horizontal float switch sensor (S940 alarm console)
TSP-KI2 Interstitial sensor riser cap kit for 2” (51 mm)
  • The FMP-HFS is 3rd party certified for use with the EVO™ 550 and EVO™ 5000.
  • The TSP-HFS is 3rd party certified for use with the S940 console.