The McDonnell & Miller FS254 flow switch NEMA 4 Tech Sheet Installation Guide General-Purpose, Liquid Flow Switches, the Series FS250 – FS251 (NEMA1 version), and FS254 (NEMA4 version). These flow switches incorporate key changes to address customer expressed needs of greater reliability and lower flow sensing capabilities in a general purpose flow switch. Features and Benefits Universal design serves the widest variety of applications For starting or stopping electrically operated equipment such as signal lights, alarms, motors, automatic burners, metering devices and others. Replacement for common flow switches from Johnson/Penn, Potter/Taco, Watts, Hydrolevel and other manufacturers. 1″ NPT Connection Two electrical knock-outs allows connection from either end Sensitivity adjusting screw makes flow adjustment easy Single pole, double throw snap switch EPDM O-ring sealed Four stainless steel paddles included -1″, 2″, 3″ & 6″ (25, 50, 80, & 150mm) Minimum temperature (fluid or ambient) 32°F (0°C) Maximum temperature 227°F (107°C) Maximum pressure 160 psi (11.3 kg/cm2) Models FS251 – NEMA 1 enclosure FS254 – NEMA 4 enclosure
