FS7-4W Series – Metal Paddle Industrial Flow Switches

November 01, 2019




Designed for installation in pipe lines from 1-1/4” and up, McDonnell & Miller standard FS7-4W series switches sense liquid flow in either direction to monitor flow/no-flow conditions. They are supplied in two paddle lengths, the paddle being trimmed during installation to permit switch actuation at the desired flow rate. As flow increases in a pipe, the paddle of the switch pivots to move out of the liquid path thereby activating the switch.

Out of stock



  • Construction: Brass or Stainless Steel
  • 11⁄4″ (32mm) NPT process connection – BSPT also available
  • Suitable applications requiring a water-tight, dust-tight or a NEMA 4X rated flow switch
  • Maximum Operating Pressure: 300 psi (21 kg/cm2); (1000 psi (70 kg/cm2) for Stainless Steel models)
  • Sensitivity adjusting screw makes flow adjustment easy
  • Operating Temperature: -65°F to + 300°F (-54°C to + 149°C)
  • Switch: SPDT, 125 VA at 120 or 240vac, 50 or 60 cycles