What are Ultrasonic Flowmeters?
The external clip type or tube type ultrasonic flow meter is a meter that measures the liquid flow in a circular tube based on the "speed difference method". It uses advanced multi-pulse technology, digital signal processing technology and error correction technology to make the flow meter more suitable for the industrial site environment, and the measurement is more convenient, economical and accurate. The products reach the advanced level at home and abroad, and can be widely used in petroleum, chemical industry, metallurgy, electric power, water supply and drainage and other fields.
Ultrasonic flowmeter
- Chinese name
- Ultrasonic flowmeter
- Foreign name
- Ultrasonic flowmeter
- Application
- Petroleum, chemical, metallurgy
- Connection method
- Pipe type, outer clip type, plug-in type
- Principle
- Velocity difference method
- Advantages
- More convenient, economical and accurate measurement
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- The external clip type or tube type ultrasonic flow meter is a meter that measures the liquid flow in a circular tube based on the "speed difference method". It uses advanced multi-pulse technology, digital signal processing technology and error correction technology to make the flow meter more suitable for the industrial site environment, and the measurement is more convenient, economical and accurate. The products reach the advanced level at home and abroad, and can be widely used in petroleum, chemical industry, metallurgy, electric power, water supply and drainage and other fields.
- Correct selection of ultrasonic flowmeter can ensure better ultrasonic flowmeter
- Pipe segment sensor parameters
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- Pipe section sensor dimensions
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- When an ultrasonic beam propagates in a liquid, the flow of the liquid will cause a small change in the propagation time, and the change in the propagation time is proportional to the flow velocity of the liquid. The relationship is as follows
- among them
- is the angle between the sound beam and the direction of liquid flow
- M is the number of linear propagations of the sound beam in the liquid
- D is the inner diameter of the pipe
- Tup is the propagation time of the sound beam in the positive direction
- Tdown is the propagation time of the sound beam in the reverse direction
- T = Tup --Tdown
- Suppose that in a stationary fluid
- When an ultrasonic wave propagates in a flowing fluid, it carries information about the velocity of the fluid. Therefore, the flow velocity of the fluid can be detected by the received ultrasonic wave, and then converted into a flow rate. According to the detection method, it can be divided into different types of ultrasonic flowmeters such as the propagation speed difference method, Doppler method, beam offset method, noise method and related methods. Ultrasonic flowmeter is one that has been applied with the rapid development of integrated circuit technology in the past ten years.
- Non-contact meter, suitable for measuring fluids that are difficult to contact and observe, as well as large pipe flow. It is linked with a water level gauge to measure the flow of open water. The use of ultrasonic flow rate does not require the installation of measuring elements in the fluid, so it does not change the flow state of the fluid and does not generate additional resistance. The installation and maintenance of the instrument can not affect the operation of the production pipeline.
- Plug-in ultrasonic flowmeter : can be installed and maintained without stopping production. The ceramic sensor is used for non-stop installation using a special drilling device. Generally, it is mono measurement. To improve the measurement accuracy, three channels can be selected.
- Segment type ultrasonic flowmeter : need to cut open the pipeline to install, but the future maintenance can not stop production. Choice of mono or tri-channel sensors.
- External clip type ultrasonic flowmeter : can perform fixed and mobile measurement. Use special coupling agent (silicone rubber cured at room temperature or high-temperature long-chain polymer grease) for installation, and the pipeline will not be damaged during installation.
- Portable ultrasonic flowmeter : portable use, built-in rechargeable lithium battery, suitable for mobile measurement, with magnetic sensor.
- 1. Non-contact measurement method, small size, easy to carry
- 2.Suitable for on-site measurement of sound conducting media of pipes of various sizes
- 3.Built-in
- The time difference ultrasonic flowmeter is a competitive flow measurement method in the world today, and its measurement line accuracy is higher than 1.0%. Due to the diversity of the industrial site, especially the environment around the pipeline, how to install and debug the ultrasonic flowmeter according to the specific environment has become an important topic in the field of ultrasonic flow measurement. This regulation details the installation details of the ultrasonic flowmeter; It further fully reflects the advantages of accuracy, reliability and stability of the ultrasonic flowmeter, greatly reducing future maintenance work and even maintenance-free.
- 1.Using the ultrasonic flowmeter probe for a period of time will cause an irregular alarm. This problem is more common when there are many impurities in the conveying medium. Solution: Clean the probes regularly (recommended once a year).
- 2. When the medium of the ultrasonic flowmeter contains liquid impurities such as water, the flowmeter's pressure tube is prone to accumulate fluid. When the temperature is low, the pressure tube will freeze and block, especially in winter in northern regions. Solution: Purge the impulse tube or heat it with electricity
- 3. Ultrasonic flowmeters have very strict requirements for pipelines. There must be no abnormal sounds, otherwise it will affect the measurement error greatly.
- During the propagation of the ultrasonic wave, its strength will be attenuated because it is blocked or absorbed by the medium and impurities in the medium. Regardless of whether it is an ultrasonic flow meter or an ultrasonic level meter, there are certain requirements for the intensity of the received sound waves, so it is necessary to suppress various attenuations.
- 4, the instantaneous flow fluctuation?
The signal strength is large, and the measurement fluid itself has large fluctuations.
Solution: Adjust the position of the probe, increase the signal strength, and ensure that the signal strength is stable.If the fluid fluctuates greatly, the position is not good.Reselect the point to ensure the working conditions of the first 10D and 5D.
5.External clip ultrasonic flowmeter has a low signal?
This depends on the technical content of the meter itself. After a lot of test cases on site, it is proved that problems such as long pipeline time, serious scaling, and large pipe diameter. The Aituoli AFTU-2W series is more than other external clamp ultrasonic flow meters. The signal is very fast and the signal is stable. .
Solution: For large pipe diameters and serious scaling, it is recommended to use a good quality external clamp ultrasonic flowmeter. The pipe where the probe is installed must be polished. Use coupling agent or coupling piece to eliminate the air between the probe and the surface of the workpiece, so that It can be effectively introduced into the pipe to ensure sufficient sound intensity transmission on the detection surface.
6. Occasionally bubbles are generated in the measurement medium. Does the ultrasonic flowmeter using the time difference method have any effect?
Today's AFTU-2W series external clip ultrasonic flowmeter has dual modes.When there are bubbles, it can automatically switch to Doppler mode to measure.When the bubbles disappear, it will automatically switch to time difference method.
7. The meter cannot be used under strong interference on site?
There is a field or high-voltage cable field strength electromagnetic interference suggestion on the site: stay away from the field or electromagnetic field interference of the high-voltage cable. 8. What is the smallest diameter of the externally clamped ultrasonic flowmeter on the market?
Answer: At present, only the smallest pipe diameter of Aituoli AFTU-2W series can measure 6mm and the temperature can be measured at 550 . Such conditions as measuring molten salt and heat transfer oil can not be achieved by other brands. of.
9. How to choose a suitable ultrasonic flowmeter?
Answer: Pipe material, pipe wall thickness and pipe diameter; fluid type, whether it contains impurities, bubbles, and whether the pipe is full; fluid temperature, flowmeter type, portable or fixed online.
- The ultrasonic flowmeter uses the time difference measurement principle: after one probe transmits a signal through the pipe wall, the medium, and the other pipe wall, it is received by another probe, and at the same time, the second probe also receives the same signal from the first probe. Due to the influence of the flow velocity of the medium, there is a time difference t between the two. According to the calculation, the conversion relationship between the flow velocity V and the time difference t V = (C2 / 2L) × t can be obtained, and then the flow value Q can be obtained.
- The development of flow measurement can be traced back to ancient water conservancy projects and urban water supply systems. In the Roman caesar era, orifice plates were used to measure the drinking water of residents. Weir method was used in ancient Egypt around 1000 BC to measure the discharge of the Nile. The well-known Dujiangyan water conservancy project in our country uses the water level of the treasure bottle mouth to observe the amount of water and so on. In the 17th century, Torri demolition laid the theoretical foundation for differential pressure flow meters, which is a milestone in flow measurement. Since then, the prototypes of many types of instruments for flow measurement in the 18th and 19th centuries have begun to form, such as weirs, tracers, pitot tubes, venturis, volumes, turbines, and target flow meters. In the 20th century, due to the rapid increase in demand for flow measurement in process industry, energy metering, and urban utilities, the rapid development of meters was promoted. The rapid development of microelectronics and computer technology has greatly promoted the upgrading of meters, and new flowmeters have sprung up like mushrooms. . So far, it is said that hundreds of flowmeters have been put on the market, and many difficult problems in field use are expected to be solved. It is relatively late to carry out modern flow measurement technology in China, and the flow meters required in the early days are imported from abroad. Flow measurement is a science that studies the change of mass. The law of mass change is the basic law of the development of the relationship between things. Therefore, the measurement object is not limited to the traditional pipeline liquid. There is a problem of flow measurement in all places where the volume change needs to be mastered. Flow rate, pressure and temperature are listed as the three major detection parameters. For a certain fluid, as long as these three parameters are known, the energy can be calculated, and these three parameters must be detected in the measurement of energy conversion. Energy conversion is the basis of all production processes and scientific experiments, so flow and pressure and temperature instruments are the most widely used.
- Portable ultrasonic flowmeter measurement function
- Technical advantages (compared to other principles)
- Not affected by electrical rate, pressure, temperature and viscosity,
- No contact with media, especially suitable for measuring corrosive media
- Simple installation and low cost
- Can be installed on existing pipes without cutting process pipes
- No flexure, no need to reduce the diameter
- No leakage
- low cost