The HFS Ex Hazardous Area Horizontal Float Switch is a float operated magnet arm on a reed switch sensor stem which has been specifically designed for the control and indication of a liquid level whilst in a potentially explosive atmosphere. Manufactured in 316L Stainless Steel, the HFS Ex can be used in both high temperature and high pressure applications and is suitable for gas and dust hazardous environments. It reliably detects the liquid level and offers voltage free contact operation, ideally suited for use as part of a pump control system or for alarm signalling.

Features include:

  • ATEX and IECEx Ex d approved.
  • Voltage free SPST or SPDT reed switch contacts.
  • Stainless Steel 316L housing and wetted components.
  • Custom mounting options available.
  • Suitable for high liquid temperatures.
  • Suitable for gas and dust hazardous areas.
  • IP68 ingress protection.
  • Suitable for low specific gravity liquids.
  • M20 or ½” NPT cable entry.

Industries the HFS Ex are commonly used in (but not limited to):

  • Hydraulic Oil
  • Food and beverage industries
  • Oil and gas industries
  • Automotive industries
  HFS Ex
Approval ATEX & IECEx Ex d
Ex Coding With Mounting Adaptor:
Ex II 1/2G 2D
Ex db IIC (*) Ga/Gb
Ex tb IIIC (*) Db
-20°C ≤T amb ≤ +85°C
* Temperature class options to suit environment and process temperatures

  • T5 / T100°C for process temperatures ≤ 85°C
  • T4 / T135°C for process temperatures ≤ 125°C
  • T3 / T200°C for process temperatures ≤ 190°C
Sensor technology Reed Switch operated by float on magnetic arm
Sensor tube and wetted materials Stainless steel 316L
Connection head material Stainless steel 316L
IP rating with suitable cable gland IP68
Approximate weight 12.kg to 2.5kg depending on mounting option selected
Float Diameter : Specific gravity ø53mm : 0.65
Other floats available
Maximum liquid temperature:
T5/100°C hazard environment
T4/135°C hazard environment
T3/200°C hazard environment
-20 to +85°C
-20 to +125°C
-20 to +190°C
Maximum head temperature -20 to +80°C
When this equipment is intended to be used in a liquid with a process temperature above 85°C it is an essential requirement that the sensor head temperature is measured to determine if the ambient air cooling is sufficient to keep the head below 80°C. See installation manual for detail.
Maximum operating pressure 150PSI / 10Bar standard
450PSI / 31Bar optional
The HFS Ex sensor float and tube can withstand the stated pressure when sealed inside a tank. The connection head and resin seal to the sensor stem must not be pressurised. The pressure of the hazardous zone must not exceed normal atmospheric conditions (0.8 to 1.1bar).
Thread connection-Sensor tube ½”-14 NPT
Thread connection-Wiring port ½”-14 NPT or M20X1.5
Voltage Free Contact Switch Rating
SPST Form A 0 to 240Vac. 1Amp. 50Watts Max
SPDT Form C 0 to 50Vdc. 0.25Amp. 20Watts Max
Certificate Download ATEX Certificate Download

IECEx Certificate Download

Datasheet Download HFS Ex Datasheet Download
Installation Instructions Download HFS Ex Installation Manual Download