Capable of monitoring flow through open channels, partially full sewer pipes, and surcharged pipes without flume or weir, MantaRay uses submerged, hydrodynamically shaped ultrasonic sensor that sheds deposits and stringers to promote reliable operation. Flow rate and total are displayed and logged in real-time, and power can be supplied via built-in, rechargeable batteries or external 12–24 Vdc batteries. Included battery charger allows continuous operation with 4–20 mA and relay outputs.