Ultrasonic Flow Meter Working Principle Advantages And Disadvantages
Ultrasonic flow meter is a meter that measures the flow rate by detecting the effect of fluid flow on the ultrasonic beam (or ultrasonic pulse).
Today Shanghai Cixi Instrument Co., Ltd. will give you a detailed introduction to the working principles, advantages and disadvantages of ultrasonic flowmeters.
1. Working principle
According to the principle of signal detection, ultrasonic flow meters can be divided into propagation velocity difference method (direct time difference method,
time difference method, phase difference method and frequency difference method), beam shift method, Doppler method, cross-correlation method, and spatial
filtering method And noise law, etc. The ultrasonic flowmeter is the same as the ultrasonic flowmeter. Because the flow channel of the instrument is not equipped
with any obstructions, it is an unobstructed flowmeter. It is a type of flowmeter suitable for solving the difficult problem of flow measurement. It is particularly prominent
in large-caliber flow measurement. It is one of the rapidly developing types of flow meters.
The ultrasonic flow meter adopts the time difference measurement principle: after one probe transmits the signal through the pipe wall, the medium, and the other
side of the pipe wall, it is received by the other probe, and at the same time, the second probe also transmits the signal and is received by the first probe. Because
of the influence of the medium flow rate, there is a time difference Δt between the two. According to the calculation, the conversion relationship between the flow rate V
and the time difference Δt can be obtained V=(C2/2L)×Δt, and then the flow value Q can be obtained
According to the above principles, ultrasonic flowmeters can be divided into two categories: time difference ultrasonic flowmeter and Doppler ultrasonic flowmeter.
Advantages and disadvantages of ultrasonic flowmeter
2, advantages and disadvantages
Ultrasonic flow sensor is a non-contact instrument, it can not only measure the flow of large pipe diameter medium, but also can be used to measure the medium that is not easy to contact and observe.
Its measurement accuracy is very high, and it is almost free from the interference of various parameters of the measured medium. It can especially solve the flow measurement problems of strong corrosive,
non-conductive, radioactive and flammable and explosive media that other instruments cannot.
The current shortcomings are mainly that the temperature range of the measurable fluid is limited by the temperature resistance of the ultrasonic transducer aluminum and the coupling material between the
transducer and the pipe, and the original data of the sound transmission velocity of the measured fluid at high temperatures is incomplete. At present, our country can only be used to measure fluids below 200°C.
In addition, the measurement circuit of the ultrasonic flowmeter is more complicated than that of the general flowmeter. This is because the flow velocity of liquid in general industrial measurement is often a
few meters per second, and the propagation speed of sound waves in the liquid is about 1500m/s. The change in the velocity of the measured fluid (flow rate) brings the largest amount of change in the speed of sound,
which is also 10- 3 orders of magnitude. If the accuracy of measuring the flow velocity is required to be 1%, the accuracy of measuring the speed of sound needs to be 10-5~10-6 orders of magnitude,
so it must have a complete measurement circuit to achieve this. The reason why the actual application can only be obtained under the prerequisite of rapid technological development.
3, the composition of ultrasonic flowmeter
Ultrasonic flow meter is composed of three parts: ultrasonic transducer, electronic circuit and flow display and accumulation system. The ultrasonic transmitting transducer converts electrical energy into ultrasonic
energy and transmits it to the fluid to be measured. The ultrasonic signal received by the receiver is amplified by the electronic circuit and converted into an electrical signal representing the flow rate for display and
totalizer for display And accumulate. In this way, the flow detection and display are realized.
Advantages and disadvantages of ultrasonic flowmeter
According to the installation method of the transducer, the ultrasonic flowmeter can be divided into three categories: clamp-on ultrasonic flowmeter, plug-in ultrasonic flowmeter, and pipe-section ultrasonic flowmeter.
4, features and functions
1. Unique signal digital processing technology makes the measurement signal of the instrument more stable, strong anti-interference ability, and more accurate measurement.
2. No mechanical transmission parts are not easy to damage, maintenance-free, and long life.
3. The circuit is more optimized, the integration is high, the power consumption is low, and the reliability is high.
4. Intelligent standard signal output, friendly man-machine interface, multiple secondary signal output for your choice.
5. The pipe section type small pipe diameter measurement is economical and convenient, and the measurement accuracy is high.
5, ultrasonic flowmeter application industry
It is widely used in petroleum, chemical industry, metallurgy, electric power, water supply and drainage and other fields. Because of the non-contact measurement, it is almost not affected by
the temperature, pressure, viscosity, density and other parameters of the measured fluid, which can solve the problems that are difficult to measure with other types of instruments. Flow measurement
problems for highly corrosive, non-conductive, radioactive, and flammable and explosive media.
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