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:
1. 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.
2, different flow rate to determine the diameter of the flow meter can meet the measurement range.
3. Different user environments.
4. 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.
5. The performance and accuracy of the ultrasonic flowmeter are selected.
6, 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.
3. Selection of electrodes and lining
Standard electrodes are used for media that do not produce non-staining electrodes such as crystals, agglomerates, and scales. Otherwise, a doctor blade electrode is used. In addition to the pure alkaline solution, the dosing solution (crystallization of boron and magnesium double salt), the washing liquid and other electromagnetic flowmeters that use the scraper electrode, the other uses the electromagnetic flowmeter of the standard electrode. Since the process pipes in the workshop are basically made of plastic insulation material, if the electromagnetic flowmeter with two electrodes is selected, the grounding ring must be configured to ensure the measurement accuracy. However, the common grounding ring is easy to corrode, and the corrosion-resistant titanium or 钽 grounding ring is high in cost, so the three-electrode electromagnetic flowmeter is selected to ensure measurement accuracy, reduce cost, and convenient installation and maintenance.
4. Flowmeter type selection
The types of electromagnetic flowmeters are divided into: integral type and split type. In Qinghai, the coldest temperature in winter is up to -30 °C. Many metered electromagnetic flowmeters are outdoors, and the environmental humidity of magnesium-lithium separation, pressure filtration and washing processes in lithium and boron systems is large. Exquisite, evaporation, conversion and other processes up to 90 °C. Therefore, the humidity of the high temperature, low temperature, high temperature fluid, vibration source and other working conditions select a split flow meter to effectively prevent the impact on the measuring components, to ensure measurement accuracy and the life of the electromagnetic flowmeter. However, it should be noted that the signal cable between the electromagnetic flowmeter sensor and the transmitter should not be too long, and the manufacturer-specific cable should be used, otherwise the measurement accuracy will be affected. The rest of the working conditions are more ideal.
Choice of protection level
The protection level of the electromagnetic flowmeter should be selected according to the actual situation. If the sensor is required to be installed below the ground and is often flooded, IP68 should be selected. If the sensor is installed above the ground, IP65 and IP67 should be selected. In any case, the display area of ??the electromagnetic flowmeter cannot be used with water or enter the water, which may cause damage to the electromagnetic flowmeter. As a chemical company, the workshop produces high humidity, but IP65 (IP65 is a water-proof type. The electromagnetic flowmeter sensor housing allows the faucet to spray water from the sensor in any direction of the sensor of the electromagnetic flowmeter. The pressure of the water spray is 30Kpa, the water output It is 12.5L/S and the distance is 3 meters.) The electromagnetic flowmeter of the protection grade fully meets the requirements of on-site measurement.
Choice of connection method
Electromagnetic flowmeters have threaded connections, flanged connections, clamps, etc. In the chemical industry, flange-connected electromagnetic flowmeters are generally used. The selection must be consistent with the process-flange engineering pressure and standards.