McDonnell & Miller FS4-3RP-T General Purpose Liquid Flow Switch

The General Purpose Liquid Flow Switch FS4-3RP-T by McDonnell & Miller is built for reliable monitoring of liquid flow in industrial piping. This paddle-style, universal switch is designed for a 1 inch nominal size with threaded end connections and a SPDT snap switch.

Rated for 7.4 Amp at 120 VAC and 3.7 Amp at 240 VAC, it accepts 125 Volt-Amp input at 120/240 VAC, 50/60 Hz. The unit handles flow from 6 to 10.2 GPM (flow) and 3.6 to 9.2 GPM (no flow), with a temperature range of 32 to 300°F and a pressure rating of 160 PSI. It incorporates a hardened stainless steel bearing and a sealed Monel bellows for durability, and includes a sensitivity-adjustable screw for precise control. UL (Canada and US) and CSA standards ensure safe, compliant operation.

• Paddle-style, universal design for versatile liquid flow detection
• SPDT snap switch for reliable electrical signaling
• 1 inch nominal size with threaded end connections for easy installation
• Durable construction with hardened stainless steel bearing, sealed Monel bellows, and two electrical knock-outs
• Adjustable sensitivity via built-in screw for precise control

Ideal for boiler feed, pump protection, chilled water lines, and HVAC applications, this General Purpose Liquid Flow Switch provides a dependable signal for alarms, motor controls, or valve actuation. Its rugged stainless steel and Monel components stand up to demanding environments, with UL and CSA certifications for global compatibility.