Measurement accuracy of elbow flow meters
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Gentlemen, I’m a newcomer to the field of instrument and control design. Some time ago, a flow meter manufacturer from Shanghai came to promote their V-cone flow meters. In the measurement of steam and water flow rates, our institute has been recommending the elbow-type flow meters produced by Hebei University of Science and Technology to our clients (due to their low pressure loss and ease of installation and maintenance). The technicians from that flow meter manufacturer explained that elbow fittings cause large errors when measuring the minimum flow rate, with errors ranging from 20% to 30% or more. Their V-cone fittings are superior to elbow fittings, as they do not suffer from such errors in measuring the minimum flow rate. I have the feeling that I’m being tricked by them; after all, no customers have reported any issues with inaccurate measurements of curved pipes during use, and it’s difficult to determine whether the measurements are accurate or not. Experts, does the curved pipe flow meter really have a problem with inaccurate lower measurement limits? Is a V-taper really better than a bent tube?
Our facility uses many elbow fittings; V-cones are prohibited for use by us, and it seems that Sinopec also prohibits them. It is said that during a hydrogen testing session, a V-cone came loose, damaged the elbow fitting, and the hydrogen leak led to an explosion!
This is my first post; please give me a lot of support!
The precision of elbow fittings is generally not high; they operate on the principle of differential pressure, and a precision of 2.5 is considered good. V-cones also work on the principle of differential pressure, but a major problem with them is that the cone portion in the middle takes up a lot of space, essentially blocking the pipeline. Moreover, the suspended structure means that over time the cone may deform, leading to blockages in the pipeline. There are actually many better flowmeters available; it is recommended that the original poster take a closer look at various websites. Learn from and seek advice from the senior students here.* Progress together
The highest accuracy of elbow flow meters is (2%–1%), while the highest accuracy of tail vortex flow meters is (1%–0.5%).
Not long after their introduction to the market, elbow valves and V-cone flow meters had a very low market share; it’s hard to say whether they were good or not. Of course, the manufacturers would claim they were good, otherwise they wouldn’t have been able to sell them. Generally, among the manufacturers that purchase flow meters, few of them actually calibrate them during use; it’s hard to say how accurate they are. Moreover, flow metering requires specific conditions in the field, and since these meters are something that cannot be seen or touched, it’s difficult to determine their accuracy. Orifice plates and vortex flow meters are more mature, which gives people more confidence.
Elbow flow meters, V-cone flow meters, etc. all belong to the category of differential pressure flow meters; likewise, Orifice flow meters and wedge flow meters also fall under this category. The specific type of flow meter to use depends on the process parameters. http://www.shakic.com/cp/product13.htm http://www.shakic.com/cp/product6.htm
The accuracy of differential pressure flow meters depends on the sensor (such as orifice plates, V-cones, etc.) as well as the accuracy of the associated differential transformer; therefore, claims in the market stating that a certain sensor can achieve a particular level of accuracy are, in my opinion, somewhat one-sided.