Ultrasonic flow meters measure the level in a channel by transmitting a pulse of sound from the face of the sensor to the surface of the flow stream and measuring the time for the echo to return. The transit time corresponds to the distance between the face of the sensor and the surface of the water.
When the meter is initially set up, a predetermined distance (or level in some meters) is set. This distance is either the zero level (no flow present) or a specific level in the flume or weir. With this initial calibration, it is only a matter of simple arithmetic to determine the liquid level.
This level is then applied to either pre-programmed discharge equations or strapping tables to output a flow rate. Because the sensor is not in contact with the water, ultrasonic sensors have no scheduled maintenance. Ultrasonic sensors are not affected by chemicals, grease, suspended solids, or silt in the flow stream.
Copyright © 2009 | Rudy Winoto