Open channel flow monitoring is a method of determining liquid volumetric flow rates in applications that rely on moving liquids through open conduits rather than enclosed pipes. Examples of these types of applications include wastewater processing effluent flows, managing water usage in agricultural irrigation channels, and monitoring flows through storm water systems. Traditionally, this type of measurement has been performed via the use of flumes or weirs in conjunction with a liquid level sensor. In recent years, global environmental concerns and increased scarcity of freshwater resources has necessitated more accurate, reliable and cost effective methods of Open Channel Flow Measurement. Two such improved methods offered by SmartMeasurement include the advanced transit time ultrasonic Area-Velocity measurement technique and the low-cost Doppler ultrasonic method.
Environmental concerns have spawned tremendous growth in the market for open channel flow meters that make use of an Area Velocity Measurement, or AVM technique. These instruments are widely used in applications such as monitoring water management systems, storm water run-off, irrigation flows, hydroelectric generating penstocks, and industrial discharges. SmartMeasurement offers two flow meters that make use of an AVM technique; the transit-time ALSONIC-AVM and the Doppler ultrasonic ALSONIC-DAVM. Detailed descriptions of the transit time and Doppler ultrasonic measurement principles can be found on the Ultrasonic Flow Meter Page.
SmartMeasurement also offers a specialized version of the ALSONIC-AVM open channel flow meter for applications where the conduit has a cylindrical geometry, such as those seen in sewer flow applications. This product, the ALSONIC-AVM-SEWER is capable of profiling velocities in in small channels with little or no straight run. It consists of the same display module as the standard ALSONIC-AVM flow meter combined with a pre-configured cylindrical 4-path transducer array as shown in the illustrations below. This easy-to-install array is available for cylindrical channels ranging from 4” through 48” (100-1200 mm) in size and will calculate the velocity (v) portion of the flow equation in the same manner as the standard version of the product with the same high level of accuracy.
The ALSONIC-DAVM flow meter from SmartMeasurement is an open channel measurement system that makes use of a pulsed Doppler transducer for velocity measurement. The velocity transducer also contains an integral hydrostatic level measurement transducer. The Doppler transducer tracks the fluid velocity while the hydrostatic level transmitter signal is used by the display module to determine the cross-sectional area of the flowing media. Please see our PDF for more details on straight run requirements:
Since the ALSONIC-DAVM open channel flow meter employs a Doppler technique, there must be some particles or bubbles present in the fluid – it will not work well with perfectly clean fluids. This device is best used in sewer and open channel application having sizes ranging from 3-15’ (1-5 meters) and higher solids content. This open channel flow meter provides users with a number of benefits including the low cost made possible by the single-sensor design, fast and easy installation, and the availability of either fixed-install or portable display packages.