Ultrasonic flowmeter uses the electronic principle to measure the flow meter. Although it has its own verification procedure, because it has the same usage management mode as the tap water industry measurement, it puts its performance requirements, measurement accuracy, verification cycle, etc. into the cold water meter. In the meantime, it has become more standardized. Since then, the use of large-caliber ultrasonic flowmeters has normative documents in the water industry.
Ultrasonic flowmeter (ultrasonic water meter) Because the measurement principle is different from electromagnetic water meter, its accuracy is different. How to choose an ultrasonic flowmeter with superior performance and precision:
The user flow range is used to determine the type, diameter, temperature, medium, etc. of the ultrasonic flowmeter, especially considering the common flow rate and the starting flow rate. The purpose is to ensure the water supply quantity, accurately measure and reduce the leakage rate. When using the water meter, the user's water meter Commonly used traffic generally cannot exceed the common flow value specified by the product.
Different flow rate to determine the diameter of the flow meter can meet the measurement range.
Different user environments.
Also consider the working pressure, the structure of the flow certificate, the form of the converter (whether bidirectional flow, current, pulse, communication interface, data storage) and the length of the connecting cable.
The performance and accuracy of the ultrasonic flowmeter are selected.
Users can learn more about the peers who are already using the ultrasonic flowmeter, to see the effect of their use, the accuracy of the measurement.
At present, industrial flow measurement generally has problems of large diameter, large flow, small diameter, small flow, high temperature liquid, and gas measurement. This is because the general flowmeter will bring manufacturing and transportation as the diameter of the measuring pipe increases. The difficulty of the above, the advantages of increased cost, increased energy loss, and inconvenient installation, ultrasonic flowmeters can be avoided. The German FLEXIM ultrasonic flowmeter measures diameters from 6mm to 6500 mm, from a few meters wide open channels, culverts to 500m wide rivers.
Ultrasonic flowmeter common problems (2)
5, the external clip type ultrasonic flowmeter signal is low?
This depends on the technical content of the instrument itself. After a large number of test cases on the spot, it proves that the long-term pipeline, serious scaling and large diameter, the Aitulel AFTU-2W series is better than other external-clip ultrasonic flowmeters. The signal is very fast and the signal is very stable. .
Solution: For large diameter and serious scaling, it is recommended to use a good quality external clamp type ultrasonic flowmeter. The pipe at the probe installation should be cleaned, and the air between the probe and the workpiece surface should be removed with a coupling agent or coupling piece to make the ultrasonic wave. It can be effectively introduced into the pipeline to ensure sufficient sound intensity transmission on the detection surface.
6. Occasionally, there are bubbles in the measurement medium. Does the ultrasonic flowmeter with the time difference method have any influence?
Today's Aitulel AFTU-2W series external clip type ultrasonic flowmeter has dual mode. When there is air bubble, it can be automatically transferred to Doppler mode to measure. When the bubble disappears, it will automatically turn into the time difference method.
7. The meter cannot be used under strong interference on the spot?
On-site inverter or high voltage cable field strong electromagnetic interference
Recommendation: Keep away from the inverter or high voltage cable field electromagnetic interference
8. What is the minimum diameter of the externally clamped ultrasonic flowmeter on the market? What is the highest temperature?
Answer: Now only the minimum diameter of the AFTU-2W series in the world can be measured to 6mm, the temperature can be measured at 550 °C, such as the measurement of molten salt and heat transfer oil, which is not possible with other brands of flowmeters. of.
9. How to choose a suitable ultrasonic flowmeter?
Answer: Pipe material, pipe wall thickness and pipe diameter; fluid type, contain impurities, air bubbles and full pipe; fluid temperature, flow meter type, portable or fixed online.
How the turbine flow meter works
The working principle of the turbine flowmeter: the fluid flows through the sensor housing. Since the blade of the impeller has a certain angle with the flow direction, the momentum of the fluid causes the blade to have a rotational moment. After the friction torque and the fluid resistance are overcome, the blade rotates, and the rotational speed is stabilized after the torque balance. Under certain conditions, the rotational speed is proportional to the flow rate. Due to the magnetic permeability of the blade, it is in the magnetic field of the signal detector (composed of permanent magnet and coil). The rotating blade cuts the magnetic field lines and periodically changes the coil. Magnetic flux, so that the two ends of the coil induce electricity
Pulse signal, which is amplified and shaped by the amplifier to form a continuous rectangular pulse wave with a certain amplitude, which can be transmitted to the display instrument to display the instantaneous flow rate and cumulative amount of the fluid. Within a certain flow range, the pulse frequency f is proportional to the instantaneous flow rate Q of the fluid flowing through the sensor. The flow equation is: Q = 3600 × f / k
In the formula:
F——pulse frequency [Hz];
K——the meter factor of the sensor [1/m], given by the checklist. If [1/L] is used, Q=3.6×f/k
Q——the instantaneous flow rate of the fluid (under working condition) [m3/h];
3600 - conversion factor.
The meter factor of each sensor is filled in the verification certificate by the manufacturer, and the k value is set in the matching display meter to display the instantaneous flow rate and the cumulative total amount.