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5. Product Introduction
5.1 Features of the product
➢
When measuring the flow rate, you may start the measuring without the need of
dismantling the pipeline and it will not adversely affect the original pipeline and the
process fluid.
➢
The LCM display module can display the instantaneous flow rate and total flow rate.
➢
4-20mA output, pulse output, RS485 Modbus communication.
➢
Durable industrial design. Highly reliable process.
➢
Suitable for measuring sewage and wastewater containing higher volumes of air
bubbles and the liquid containing particular impurities.
5.2 Working theory
The primary measuring theory of the Doppler Ultrasonic Flow Meter is to measure the
flowing speed according to the Doppler Effect. When executing the measuring, the
liquid medium should contain tiny particles (impurities or air bubbles) that are moving at
the same speed as the liquid. During the measuring process, the transducer mounted
on the Doppler Flow Meter will transmit the ultrasonic pulse signal to the liquid. When
hitting the tiny particles in the liquid, the pulse signal will be reflected by the ultrasonic
signal. In this way, the frequency will change when the reflective wave is received by
the transducer. Based on the variation value of the frequency and the Doppler Effect,
the Doppler Flow Meter will then calculate the moving speed of the particulars when
flowing through the measuring point. Through the programmed flow field, the Flow
Meter calculates the average flowing velocity along the entire sectional profile.
Described below
are the working
theory and
υ =
2������������ − ∆����������
formula:
※The resonance point is intended for transmitting the frequency and the
reverse resonance point is designed for receiving the returned frequency.
During the entire process, the Doppler transducer is used for transmitting
and receiving the signals. Therefore, the frequency of the transmitted
signal is set as 640KHz.
V = Velocity
C = Acoustic speed of fluid
∆�� × ��
Δf = Calculated by demodulating the hardware
circuit.
fo: Signal transmission frequency: 640KHz
Θ: Angle of incidence
8
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