em-tec BioProTT™ Clamp-On Transducers operate based on the transit-time ultrasound principle. These transducers constitute four piezoceramics accommodated in a fixed location within the transducer body. The piezoceramics are set in a particular angle α with respect to the flowing medium. Tubing that is inserted into the cavity of the transducer is enclosed by the piezoceramics in an “X” pattern.
Transit-Time Ultrasound Principle
The X pattern arrangement of the em-tec BioProTT™ Clamp-On Transducers illuminates the whole cross-section of the flow channel by four sound paths. Consequently, all velocities contributing to the flow profile are considered thereby making it possible to accurately determine the overall flow rate.
A high-frequency voltage impulse is applied so as to excite the piezoceramics and pass ultrasound waves from one ceramic to the opposite one, with each one serving alternately as transmitter and receiver. The duration of time the signal takes to move from one crystal to another (transit time) is measured by the electronics of the flow transmitter.
As the ultrasound beam travels from one crystal to the other, it should pass through the tubing and medium present inside the transducer cavity. The fluid moving through the tubing will have an effect on the ultrasound beam. While signals that travel with the fluid flow have quicker transit time, those that travel against the flow will have slower transit times. The difference between the upstream transit times (against the flow) and downstream transit times (with the flow) is proportional to the volumetric flow rate.
This information has been sourced, reviewed and adapted from materials provided by em-tec GmbH.
For more information on this source, please visit em-tec GmbH.