The DFM 5.1 Doppler Flow Meter from Greyline Instruments measures flow from outside a pipe. The clamp-on ultrasonic sensor mounts on any 1/2-inch I.D. or larger pipe. It is designed for difficult liquids like wastewater, biosolids, slurries, abrasives or any liquid with bubbles or suspended solids. Calibration and startup is simple with the built-in, five-button keypad. It includes a large, backlit display and totalizer; isolated 4-20mA output; and six control relays. Options include a built-in data logger and reporting system with USB output, Windows software and intrinsically safe sensor. 855-300-9151; www.greyline.com