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Noliac Ceramics offers piezo bulk/monolayer transducers for ultrasonic applications and flowmeters.

PCM41 and PCM40 are low-loss materials designed for high-power applications.

The low dielectric and mechanical losses (tgd, Qm) combined with high piezoelectric charge constant (d33) make them suitable for ultrasonic applications.

Depending on the shape and size of the flowmeter, Noliac can customise the component according to specifications.

The company is able to manufacture all common monolayer piezoceramic shapes, such as discs, rings, tubes, rods, bars and plates including shear mode configurations.

Additionally, Noliac can customise according to dimension tolerances, as well as tolerances for dielectric and electromechanical properties.

The measurement of the Doppler effect and the propagation time are the two fundamental measurement techniques used in ultrasonic flow rate measurement.

The piezo transducers used generate ultrasonic waves that are introduced into the liquid at an angle to the direction of flow.

With the Doppler principle, the phase and frequency shift of the ultrasonic waves, scattered and reflected by particles of liquid, are evaluated.

The frequency shift between the wavefront emitted and received by the same piezo transducer is a measure of the flow speed.

The measurement of the propagation time is based on transmitting and receiving ultrasonic pulses on alternating sides, in the direction of flow and against it.

Two piezo transducers operating as both transmitter and receiver are arranged diagonally to the direction of flow in an acoustic cell.

Emission of the wave burst in the flowing medium (liquid or gaseous) causes a superposition of sound propagation speed and flow speed.

The flow speed is proportional to the reciprocal of the difference in the propagation times in the direction of the flow and in the opposite direction.

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