McDonnell & Miller FS254 General Purpose Liquid Flow Switch

The FS254 General Purpose Liquid Flow Switch from McDonnell & Miller delivers dependable flow monitoring for commercial heating, cooling, and process systems. This paddle-type universal flow switch uses a 1-inch nominal size with threaded end connections to integrate easily into standard piping.

Designed for rugged environments, the FS254 houses an SPDT snap switch inside a NEMA 4 enclosure, with an adjustable sensitivity screw and an EPDM O-ring for a secure seal. It’s built to withstand up to 160 psi and operates from 32 to 225°F, making it suitable for a variety of liquids and installations.

Electrical and performance specs provide versatile control: 7.4 A at 120 VAC and 3.7 A at 240 VAC, with a 125 VA input rating at 120/240 VAC (50/60 Hz). The device detects flow across 5.8–17.6 GPM (flow) and 5.1–6.53 GPM (no flow). UL (Canada/US) and CSA listings ensure utility in certified applications.

• Paddle-type universal design with adjustable sensitivity for precise control
• 1" nominal size with threaded x threaded end connections
• SPDT snap switch in a rugged NEMA 4 enclosure
• Flow range: 5.8–17.6 GPM; No-flow range: 5.1–6.53 GPM
• Temperature range 32–225°F and 160 psi pressure rating
• Electrical: 7.4 A @ 120 VAC; 3.7 A @ 240 VAC; 125 VA @ 120/240 VAC
• Includes EPDM O-ring; UL/CSA listed