Xylem FS251 General Purpose Liquid Flow Switch 1" NPT NEMA 1

The Xylem McDonnell & Miller FS251 is a reliable general purpose liquid flow switch designed to monitor and control fluid flow in HVAC, boiler, and industrial applications. This versatile flow switch starts or stops electrically operated equipment such as signal lights, alarms, motors, automatic burners, and metering devices when water flow is detected in a system.

Key Features:

• 1" NPT male threaded pipe connection for easy installation
• NEMA 1 enclosure for indoor applications
• Single pole, double throw (SPDT) snap switch rated at 7.4A @ 120V or 3.7A @ 240V
• Includes four stainless steel paddles (1", 2", 3", and 6") to accommodate various pipe sizes
• Adjustable flow sensitivity with integrated adjustment screw (minimum flow rate: 5.8 GPM)
• EPDM O-ring sealed for reliable performance
• Maximum pressure rating: 160 PSI
• Temperature range: 32°F to 250°F (fluid or ambient)
• Maximum fluid velocity: 10 feet per second

The FS251 features a universal design that serves the widest variety of applications and can replace common flow switches from Johnson/Penn, Potter/Taco, Watts, Hydrolevel, and other manufacturers. This switch replaces the older FS4-3 model and incorporates key improvements for greater reliability and lower flow sensing capabilities. Manufactured part number 120611.