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.
The lining material should be selected according to the corrosiveness, wear and temperature of the tested medium:
First, natural rubber (soft rubber)
1, better elasticity, wear resistance and tearing force
2, resistant to general weak acid, weak alkali corrosion
3. Water and sewage
Second, acid-resistant rubber (hard rubber)
It can withstand the corrosion of hydrochloric acid, acetic acid, oxalic acid, ammonia water, phosphoric acid and 50% sulfuric acid, sodium hydroxide and potassium hydroxide at normal temperature, but it is not resistant to corrosion by strong oxidants.
It can measure general acid, alkali and salt solutions.
Third, neoprene (Neoprene)
1, excellent elasticity, high tearing force, good wear resistance
2, resistant to general low concentration of acid and alkali, salt solution corrosion, but not resistant to oxidation of the medium, and temperature requirements <80 ° C;
It can measure water, sewage, mud and pulp.
Fourth, Polyurethane (Polyurethane)
1, excellent wear resistance
2, poor acid and alkali resistance, temperature requirements <40 ° C
Measure medium-strongly worn coal slurry, mud and slurry
Five, polytetrafluoroethylene (PTFE)
1. Boiling hydrochloric acid, sulfuric acid, nitric acid, aqua regia, concentrated alkali and various organic solvents
2, good wear resistance, poor bonding performance, temperature requirements -80 ~ +180 ° C;
Measuring concentration, concentrated alkali strong corrosive solution and sanitary medium
The electromagnetic flowmeter has a large measuring range, usually 20:1~50:1, and the optional flow range is wide; the diameter of the electromagnetic flowmeter is wider than other types of flowmeters, from a few millimeters to 3 meters; the positive and negative two-way flow can be measured. The pulsating flow rate can also be measured as long as the pulsation frequency is much lower than the excitation frequency; the meter output is linear in nature; it is easy to select the material type of the fluid contact member, and can be applied to corrosive fluids and the like. Since the electromagnetic flowmeter measures much more with suspended solids or dirt than other flow meters, the probability of failure of the inner wall adhesion layer is relatively high. If the electrical conductivity of the adhesion layer is close to the liquid conductivity, the instrument can output the signal normally, but only change the flow area to form a hidden fault of the measurement error; if it is a high conductivity adhesion layer, the electromotive force between the electrodes will be short-circuited; if it is an insulating adhesion layer The surface of the electrode is insulated to disconnect the measuring circuit. The latter two phenomena will make the meter inoperable.