The Model DFS 5.1 Doppler Flow Switch from Greyline Instruments measures liquid flow with a noncontacting ultrasonic sensor mounted on the outside of 1/2-inch-diameter or larger pipes. It installs in minutes, no pipe drilling or cutting is required and there is no maintenance. It is designed for pump protection, valve control and flow/no-flow alarms, and is ideal to control wastewater, slurries, caustics, acids and difficult liquids. The watertight NEMA4X switch enclosure includes a 5-amp DPDT control relay with adjustable on and off setpoint controls, adjustable time delay, flow rate bar graph and relay status LEDs. A sensor mounting kit is included with each switch and the sensor cable can be extended up to 492 feet. 888/473-9546; www.greyline.com