Starting at $233.00
  • Usually ships in 2-3 weeks



  • Flow Rate Settings: 0.75 GPM to 10.0 GPM
  • Port Size: 3/4"
  • Primary Construction Material: Bronze
  • Fixed or Adjustable settings
  • Maximum Pressure Rating: 400 PSI @ 100°F (operating); 800 PSI @ 100°F (proof)
  • Operating Temperature: -20 to 180°F
  • Repeatability: 1% Maximum Deviation
  • Set Point Accuracy: ±10%
  • Set Point Differential: 15% Maximum
  • Switch: SPDT, 20 VA


The Gems FS-400 series flow switches are highly accurate, general purpose flow switches with a 90° flow path. These switches feature a rugged bronze body that resists shock and vibration. Designed to protect bearings, gears and cooling systems by triggering alarms on interlocking shutdown circuitry when flow rate is improper, the FS-400 series boasts 1% repeatability.

The FS-400 series has a 3/4" process connection with fixed flow settings ranging from 0.75 to 10.0 gpm. There are also three adjustable flow settings available which can be easily changed without disassembly. A shuttle by-pass vane inside the housing is controlled externally using an ordinary flat-blade screwdriver. The simple and reliable design is suitable for operating temperatures from -20 to 180°F and line pressures up to 400 psig. The FS-400 series utilizes a SPST switch.

Applications for the Gems FS-400 Series flow switch:

  • Protect Bearings or Gears: oil separators, fuel systems, pumps, compressors, presses
  • Electronics or Machinery: heat exchangers, semiconductor manufacturing equipment, induction furnaces, radio transmitters
  • Process Systems: water filtration and reverse osmosis, chlorinators, de-icers, sterilizers, evaporators


This product can be used in the following applications: