⎝⎛星力捕鱼⎞⎠

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Lunan
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Industry Information
Do not choose a large differential pressure blindly when calculating the opening diameter of a V-cone flowmeter
2012-3-13 11:25:51

Everyone knows that differential pressure flowmeters using orifice plates, nozzles and venturis as throttling devices have been successfully used in industry for more than 100 years. They do not require experimental calibration to determine the relationship between differential pressure and flow, and to estimate their measurement errors. Orifice flowmeters are typical of them. They have a simple structure, are sturdy, easy to replicate, strong in general, and low in price. They have been widely used. However, those who are more familiar with throttling devices should also know that when the orifice flowmeter is used in the field, there are also unavoidable disadvantages: large pressure loss, small range ratio, and easy wear. 的优化改进工作一直在不断的完善,比如针对腐蚀性的场合,应用楔形孔板流量计等。 The optimization and improvement of the V-cone flowmeter has been continuously improved, such as the application of wedge-shaped orifice plate flowmeters for corrosive occasions.
However, from the company's sales in recent years, V-cone flowmeters have opened a new page for differential pressure flowmeters, which are constantly making up for the shortcomings of differential pressure throttling devices led by orifice flowmeters. The following will give you a focus on the measurement principle of the V-cone flowmeter:

Because the fluid is not forced to shrink near the centerline of the pipe, and it is no longer due to a block (such as an orifice plate flow meter) that causes the fluid to suddenly change its flow direction, it is achieved by using a novel inner cone throttle device. The constriction (throttling) of the fluid gradually towards the inner wall of the tube makes the V-shaped inner cone throttling device have a series of unique advantages. The throttling of this throttling device is gradually produced, so it does not have high requirements on the flow of fluid, and it has the function of automatically correcting the velocity distribution of the distorted stream, it has a rectifying effect, and it can largely eliminate vortex II. Secondary flow, which makes this throttling device greatly reduce the requirements of the front and back straight pipe sections. In addition, this throttling device can only generate high-frequency and low-amplitude surge (small eddy current) downstream of it. Therefore, the differential pressure signal measured by the differential pressure transmitter is a low-noise signal. Pressures with resolution better than 25PA can be measured. In this way, only a differential pressure transmitter can be used to obtain a wide range ratio (the range ratio can be greater than 15: 1) and good repeatability (better than 0.1%). However, due to the use time of the V flowmeter, there are still some shortcomings compared with the orifice flowmeter when it is used in the field. For example, when the V-cone flowmeter wants to obtain higher accuracy, it must pass through the solid flow. Calibration, so it seems more tedious. As a manufacturer, we have this obligation to assume the obligation to improve the data of the V-cone flowmeter. We hope that all sectors of society will give certain support


等节流装置根据现场参数计算开孔直径的时候,会涉及到这么一个问题,就是差压变送器的最大差压值如何选取的问题? Manufacturers of production throttling devices all know that when calculating the opening diameter based on field parameters for orifice devices such as orifice plate flow meters and V-cone flow meters , such a problem is related to the maximum differential pressure of the differential pressure transmitter. How to choose the value? How to choose the differential pressure value, and how big should I choose? It is related to many factors, such as uncertainty, straight forward and backward pipe sections, etc. Therefore, when calculating the opening diameter of orifice plate flowmeters and V-cone flowmeters, you must not blindly choose a large differential pressure, but comprehensive consideration Some related factors.

1. When the differential pressure value is large, the minimum straight pipe section required can be shorter. For this feature, for the orifice plate flowmeter, considering the economic factors in all aspects, the opening value with the largest differential pressure should be selected; and V The cone flowmeter is relatively better. If the on-site fluid is Newtonian fluid, the straight tube requirements of the V-cone flowmeter itself are relatively low. Even if it is shorter, in comparison, there is no 2. differential pressure value. When the value is larger, the β value becomes smaller, and the minimum recommended Reynolds number is smaller. In this case, the actual Reynolds number may be much larger than the recommended Reynolds number, so the flow coefficient becomes stable and the measurement accuracy is improved. 3. For a differential pressure transmitter, a large differential pressure is more stable than a small differential pressure. 4. The basics introduced above are all the advantages when the differential pressure is large, but many times, when they have reached a certain level, they will definitely bring certain disadvantages. 相比起来,稍微适中点。 Those who are familiar with the process technology of orifice plate flowmeters and V-cone flowmeters should know that when the differential pressure is too large, the direct consequence is that the openings become small, and the relative pressure loss is also large. The plate flow meter has a large pressure loss. If this is added, the cost due to this pressure loss is considerable for the entire process system. Compared with the V-cone flow meter , it is slightly more moderate.

Therefore, in our normal production process, we cannot blindly suggest that our customers choose a large differential pressure value, and we must be truly responsible for customers and enterprises.