Flo-Dar™ Sensor - Hachflow

General informationDepth measurementThe water depth is measured using an ultrasonic pulse echo sensor. An electronic pulseis sent to the water surface and a portion of the signal is returned to the sensor. Thetransit time to the surface and back is used to calculate the distance from the watersurface to the sensor. The pipe diameter is used to convert the distance to water depth.The depth sensor on the Flo-Dar unit can measure distances up to 1.5 m (5 ft). For largerchannels, an extended range sensor is available to measure up to 6.1 m (20 ft).During surcharge conditions, a pressure transducer in the Flo-Dar unit is used tomeasure depth.Flow calculationsThe velocity and depth measurements are used with the pipe diameter to determine theflow rate. The flow rate is calculated from the continuity equation (1):(1) Flow rate = Average velocity × AreawhereFlow rate = volume of liquid that passes the sensor per unit time (e.g. 200 gallons per minute)Average velocity = average velocity of the liquid, calculated using surface velocitymeasurements and algorithmsArea = cross-sectional area of the liquid in the channel, calculated using the channeldimensions and depth measurement.9