New member seeking help; hope everyone can assist
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1. The V-cone flow meters used in the factory where I work always show excessive deviations in production. All routine inspections have been carried out – there are no blockages or leaks – and the operating pressure and temperature have also been compared with the design values, which are fairly similar. Has anyone encountered such a problem? How did you resolve it? 2. Since the cone is relatively large (1.4m), the differential pressure range is very small; typically, the differential pressure used is around 0.1–0.2 Kpa. Are there any better methods to address the deviations that occur in flow meters operating under such low differential pressures? 3. We also have a V-cone used for settlement, which was subjected to third-party calibration before being put into use; calibration certificates were issued for aspects such as the cone shape and differential pressure as well as the pressure transducer. The question is: is there a calibration cycle for the V-cone itself? Is a recheck needed after some time? Is there a clear written rule? It has been in use for two years now; only the differential pressure and pressure transducers have been rechecked. There is no inspection done on the V-cone itself – is it necessary to carry out a recheck? I hope to get everyone’s help, thank you! ! !
Liu Ming, is it a problem with the operating conditions? Is it not applicable?
This one won’t; it’s a flow meter specified according to the design conditions
What does a V-cone measure? Gas? It’s not easy to measure gas in the first place. If it is said that the process deviation is large, is there any evidence for that? It needs to be determined, right? The differential pressure is small; if there is a slight difference in the instrument’s zero point, the measurement will be inaccurate
Question 1: The V-cone is already a standard throttling device; see ISO5167-5 for details. It’s not clear whether it is included in the national standards as they have not been translated yet. The procedure used for calibration is JJG640. Question 2: Is it possible that the uncertainty of such large gas standard devices is high? Water can be used for testing by applying Reynolds similarity, as the discharge coefficient remains consistent at the same Reynolds number
Based on what the poster said, has the transmitter been replaced or not?
There’s no problem with the transmitter; it hasn’t been replaced
The medium is exhaust gas; the static pressure is around 4 Kpa, and the differential pressure is indicated by a gauge of 3051 1A
I’ve memorized them all: 3051 CD1A range –6.22 to +6.22 KPA, CD2 range –62.2 to +62.2 kPA. :)
I think the problem lies with the V-cone. 1. The measurement range is too small ； 2. Is there erosion or wear on the V-cone (this usually results in a lower indicated value)? ； If the indication is high (it may indicate issues such as scaling of process media on the V-taper).