Starting at $114.00
  • Usually ships in 2-3 weeks



  • Flow Rate Settings: 0.1 GPM to 1.5 GPM
  • Port Size: 9/16" - 18 UNF
  • Primary Construction Material: Ryton®
  • More robust porting hubs offer better structural integrity
  • Molded cable grommet offers improved moisture protection
  • Maximum Operating Pressure: 250 PSIG @ 70°F
  • Operating Temperature: 0 to 225°F
  • Set Point Accuracy: ±15% Maximum
  • Set Point Differential: 20% Maximum
  • Switch: SPST or SPDT, 20 VA (SPDT: 240 VAC Max.)
  • Recommended Filtration: 50 Microns or Better


The Gems FS-4 series flow switches makes flow protection economical for a broad range of industrial applications such as welders, lubrication systems, medical sterilizers and laundry chemicals dispensing. The FS-4 features a Ryton body as well as robust porting hubs for improved structural integrity while molded cable grommets offer improved moisture protection.

The FS-4 series has a 9/16" - 18 UNF process connection. Flow settings for the unit range from 0.10 to 1.50 gpm. The simple and reliable design is suitable for operating temperatures from 0 to 225°F and line pressures up to 250 psig. SPST (normally open or normally closed) or SPDT switches are available.

Applications for the Gems FS-4 Series flow switch:

  • Electronic Equipment: Laser Heads, Welders, Power Supplies, High Speed Spindles, X-Ray Tubes, Semiconductor Equipment
  • Bearings or Gears: Presses, Rotating Equipment, Conveyors, Machine Tools, Robotics
  • Processing & Dispensing Equipment: Water Purifications and Filtering, X-Ray Film Processing, Beverage Dispensing, Chemical Additives, Gas Sampling, Distilling