Transducers; Flow Cell Optional Pressure Sensor; Figure 5: Spu Compartments; Figure 6: Spu Cover - Elster Q.Sonic PLUS Quick Start Manual

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Figure 5: SPU compartments

The rear compartment comprises a field terminal board used for connecting the Ultrasonic
Flowmeter Series 6 to the end users applications. For detailed information about this see
chapter 5.2.2.
4.3

Transducers

The ultrasonic signals required for the flow measurement are generated and received by
ultrasonic transducers.
Piezoelectric transducers employ crystals or ceramics that are set into vibration when an
alternating voltage is applied to the piezoelectric element. The vibrating element generates
sound waves in the gas. Since the piezoelectric effect is reversible, the element will
become electrically polarised and produce voltages related to the mechanical strain, when
the crystal is distorted by the action of incident sound waves. Because the acoustic
impedance of the gas is much smaller compared to the acoustic impedance of the
piezoelectric element, and to maximise the acoustic efficiency, a matching layer is
employed between the gas and the piezoelectric element.
The transducers used in the Ultrasonic Flowmeter Series 6 are type 'NG', see Figure 7.
Figure 8 visualises the NG transducer with the mounting bracket.

Figure 7: NG transducer

4.4

Flow cell optional pressure sensor

As an optional feature the UFM can be equipped with a pressure sensor. This pressure
sensor is used for:
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DOCUMENT TITLE
ULTRASONIC FLOWMETER SERIES 6, MODELS Q.SONIC
SUBTITLE
QUICK START MANUAL
DOCUMENT NUMBER
22.100.200.000.02/2

Figure 6: SPU cover

Figure 8: NG transducer with the mounting bracket.

22.100.200.000.02_2_B ULTRASONIC FLOWMETER SERIES 6.DOC
PLUS
REVISION REVISION DATE
B 2013-02-22
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