特点如下： V cone flowmeter features are as follows:
1: The flow meter is a pure mechanical body, so it is resistant to high temperature, high pressure, corrosion and vibration. 2: The boundary layer effect formed by the unique structure of the flow meter prevents the key parts of the throttle from abrasion, so the geometric size can be maintained for a long time. Change, so it can work stably for a long time without calibration.
3: Low requirements for straight pipe sections: The Bohr's equation requires that the measured fluid be an ideal fluid. This is simply impossible in practical applications. In many cases, the fluid distribution is uneven, such as elbows, valves, shrinkage, and expansion. Pumps, tees, etc. are a difficult problem for other instruments. The V-cone flowmeter can evenly distribute the fluid under extremely harsh conditions. For example, there are single elbows and double elbows immediately upstream of the meter. After the cone “rectification”, the fluid distribution is more uniform to ensure that the meter can obtain under severe conditions. Higher measurement accuracy. Because the V-type flowmeter can evenly distribute the fluid curve, compared with other types of differential pressure flowmeters, the requirements for the upstream and downstream straight pipe sections are less. It is recommended to leave 0-3D straight pipe sections upstream during installation. , Leave a straight tube of 0-1D downstream. When the size of the user's pipeline is large, the price of the pipeline is high, or the straight pipe section is not enough, the V-cone flowmeter will be the best choice. In the past ten years, the test has been performed on a single bent pipe at 90 ° C or two double bent pipes that are not on a plane upstream of the V-type flowmeter. The test results show that the V-cone type flowmeter can be used next to it. There is an elbow or a double elbow that is not on the same plane without affecting the measurement accuracy.
4: Good repeatability: The repeatability of the V-cone flowmeter is very good, which is ± 0.1%
5: High accuracy: The accuracy of the V-cone flowmeter is ± 0.5% of the measured value, and the trade measurement level is ± 0.3% (the system accuracy needs to refer to the application conditions and the accuracy of the secondary instrument).
的量程较其它类型的差压流量计大得多，正常情况下为10：1，若有必要不是也可加大。 6: Wide range ratio: The range of the V-cone type flowmeter is much larger than that of other types of differential pressure flowmeters. It is normally 10: 1, and it can be increased if necessary. When the Reynolds number is higher than 8000, the output signal is linear. If it is lower than 8000, it can be measured, but the output signal needs to be corrected according to the curve.
As a new type of throttling device, the V-cone flowmeter has been overheated in recent years. Low pressure loss and high accuracy are the key points of its call compared to other standard throttling devices. But does the V-cone flowmeter really have such a high measurement advantage as it is said now? The following are the technical characteristics of the mutual restriction of the V-cone flowmeter summarized by the author with reference to relevant data and field installation experience.
1. I should have read the V-cone technical manuals of many manufacturers on the site. The β value above may not be of much concern to you. Many manufacturers' labels are in the range of 0.4-0.9. But in fact this and the low requirements of the straight section are contradictory. After a long-term experiment in our factory, if you want to meet the high-precision measurement requirements under the lower requirements of straight pipe sections, the β value must meet the range of 0.45-0.6, but then there is another problem If the diameter of the cone is in this range, the pressure loss is only 90% of that of a standard orifice plate, so the statement that the pressure loss is small is lost. And as suggested by some manufacturers, the value is more than 0.8. In this case, the pressure loss can be reduced to half of the standard orifice plate, but the rectification effect is lost, and the characteristics of low straight pipe requirements on the site are also lost.
2, is the rationality of taking the pressure point. 锥体本身有整流的作用，但是对正压取压却只能望而却步，起不到半点作用，所以如果现场前面直管段要求不够的话，正压取压同样取不到具有代表性的静压。 Everyone who has used the V cone knows that the positive pressure is directly taken from the on-site pipeline pressure. Although the V cone flowmeter cone itself has a rectifying effect, it can only be discouraged from taking positive pressure. Function, so if the requirements of the straight pipe section in front of the site are not enough, the positive pressure can not take the representative static pressure. Therefore, no matter which type of flow meter, it is definitely not a panacea, and it can only adapt to a certain field and obtain better measurement results.