How does the Transit-Time Ultrasound Method work?
em-tec offers many different flow measurement systems which are based on the transit-time ultrasound principle:
Transducers consist of four piezoceramics housed in a fixed location within the transducer body. The piezoceramics are arranged in an “X” pattern which acoustically illuminates the whole cross section of the flow channel by four sound paths. A high frequency voltage impulse is used to excite the piezoceramics and transmit ultrasound waves from one ceramic to the opposing one, with each one acting alternately as transmitter and receiver. The length of time it takes the signal to travel from one crystal to another (transit time) is measured by the electronics of the flow transmitter. The difference between the upstream transit times (against the flow) and downstream transit times (with the flow) is proportional to the volumetric flow rate.