McDonnell & Miller 114400 Model FS4-3 – 1″ NPT Snap Liquid Flow Switch
McDonnell & Miller model number FS4-3 is a 1″ NPT, 120 volt, single pole, double throw, snap liquid flow switch for universal general purpose applications for starting and stopping electrical operation equipment such as signals, alarms, motors, automatic burners, and metering devices. This switch can be installed into a tee and comes with reinforced 1″, 2″, 3″, and 6″ brass paddles. It is also has a sensitivity adjustment screw for easy flow adjustment, a maximum temperature of 300°F, and a 160 psi maximum operating pressure.