The new DFM 5.0 doppler flowmeter from Greyline Instruments measures flow from outside a pipe. The strap-on ultrasonic sensor mounts on any pipe ?-in. ID or larger. It is designed for “difficult” liquids, such as wastewater, sludge, slurries, abrasives or any liquid with bubbles or suspended solids. Calibration and startup is simple with the five-button keypad.