Main problems and solutions of the hottest vortex

The main problems and solutions of vortex flowmeter

the main problems are: ① the indication is inaccurate for a long time; ② There is no indication at all; ③ Indicates a wide range of fluctuations, unable to read; ④ Indication does not return to zero; ⑤ No indication at low flow; ⑧ The indication is OK in case of large flow, and inaccurate in case of small flow; ⑦ When the flow changes, the change of indication cannot keep up; ⑧ The K coefficient of the instrument cannot be determined, and the data at many places are inconsistent

analysis and solutions

summarize the main causes of these problems, mainly involving the following aspects:

1, problems in model selection. Some vortex street sensors choose a large specification due to the change of process conditions in the selection of caliber or after the design and selection. The actual selection should choose the smallest caliber as possible to improve the measurement accuracy. The reasons in this regard are mainly related to problems ①, ③ and ⑥. For example, a vortex pipeline is designed to be used by several equipment. Due to the fact that some process equipment is sometimes not used, the current actual use flow is reduced. The actual use causes the original design selection diameter to be too large, which is equivalent to raising the lower limit of measurable flow. The indication of process pipeline can not be guaranteed when the flow is small, but it can be used when the flow is large, because it is sometimes too difficult to rebuild. The change of technological conditions is only the performance characteristics of the temporary microcomputer controlled electric control testing machine. It can be combined with the re setting of parameters to improve the accuracy of indication

2. Installation problems. The main reason is that the length of the straight pipe in front of the sensor is not enough, which affects the measurement accuracy. The reason in this regard is mainly related to problem ①. For example, the straight pipe section in front of the sensor is obviously insufficient. Since fic203 is not used for measurement, it is only used for control, so the current accuracy can be used, which is equivalent to degraded use

3. Reasons for parameter setting direction. Due to parameter error, the instrument indication is incorrect. Parameter error makes the calculation of secondary instrument full frequency wrong, and the reason in this regard is mainly related to problems ① and ③. The similar full-scale frequency makes the indication inaccurate for a long time. The actual full-scale frequency is larger than the calculated full-scale frequency, which makes the indication fluctuate in a large range and cannot be read. The inconsistency of parameters in the data affects the final determination of parameters. Finally, the parameters are determined through re calibration and mutual comparison, which solves this problem

4. Secondary instrument failure. There are many faults in this part, including: there is a disconnection in the primary instrument circuit board, the display of individual bits in the range setting is bad, and the display of individual bits in the K-factor setting is bad, making it impossible to determine the range setting and K-factor setting. As stated in the report, this part of the reason is mainly related to problems ① and ②. By repairing the corresponding fault, the problem can be solved

5. Four circuit connection problem. On the surface of some circuits, the line connection is very good. Careful inspection shows that some connectors have actually become loose, causing circuit interruption. Although some connectors are tightly connected, the fastening screws are fastened on the wire cover due to the problem of the auxiliary line, which also makes the circuit interruption. This part of the reason is mainly related to problem ②

6. Connection between secondary instrument and subsequent instrument. The Ma output circuit of the secondary instrument is interrupted due to the problems of the subsequent instrument or the maintenance of the subsequent instrument. For this type of secondary instrument, this part of the reason is mainly related to problem ②. Especially for the subsequent recorders, when the recorders are damaged for a long time and cannot be repaired, we must pay attention to short circuit the output of the secondary instrument

7. There is no indication in the circuit due to the fault of the horizontal axis cable of the secondary instrument. Due to long-term operation and the influence of dust, the fault of the flat shaft cable is caused. The problem can be solved by cleaning or replacing the flat shaft wire

8. For the problem ⑦, the main reason is that the fixing screw of the secondary instrument display header coil is loose, causing the header to sink, the pointer and the case friction is large, and the action is not flexible. The problem can be solved by adjusting the header and re fixing it

9. Environmental problems. In particular, the sensor installed in the underground shaft causes the circuit board to be affected by moisture due to high environmental humidity, which is mainly related to problems ② and ②. Through the corresponding technical transformation measures, some sensors with high environmental humidity have been separated from the probe part and the conversion part again, and a separate sensor has been used, so the working environment has been improved, and this part of the instrument runs well a few days ago

10. Due to poor on-site adjustment or changes in the actual situation after adjustment. Due to the poor balance adjustment and sensitivity adjustment of on-site vibration and noise. Or due to the change of site conditions after a period of operation after adjustment, the indication problems are mainly related to problems ④ and ⑤. Use the oscilloscope and readjust it in combination with the process operation

requirements of vortex flowmeter [3] installation on straight pipe section:

correct selection of installation point and correct installation of flowmeter are very important links. If the installation link is wrong, the light will affect the measurement accuracy, and the heavy will affect the service life of flowmeter, and even damage the flowmeter in our environment

the installation of vortex flowmeter is very important for the requirements of straight pipe section. Its detailed requirements are as follows:

the flowmeter has certain requirements for the upstream and downstream straight pipe sections on the installation point, otherwise the measurement accuracy will be affected

if there is a reducer upstream of the installation point of the flowmeter, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 15d (D is the pipe diameter), and the downstream should have an equal diameter straight pipe section of not less than 5D

if there is a diffuser upstream of the installation point of the flowmeter, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 18D (D is the pipe diameter), and the downstream should have an equal diameter straight pipe section of not less than 5D

if there is a 90 ° elbow or downstream joint upstream of the installation point of the flowmeter, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 20d, and the downstream should have no less than 1. Add appropriate cooling medium to the cooling tank of the low temperature tank to the equal diameter straight pipe section of 5D

if there is a 90 ° elbow on the same plane upstream of the flowmeter installation point, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 25d, and the downstream should have an equal diameter straight pipe section of not less than 5D

the flow regulating valve or pressure regulating valve should be installed as far as 5D downstream of the flowmeter. If it must be installed upstream of the flowmeter, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 25d, and the downstream should have an equal diameter straight pipe section of not less than 5D

if there are piston or plunger pumps, piston or roots fans and compressors in the upstream of the flowmeter, the upstream of the flowmeter should have an equal diameter straight pipe section of not less than 25d, and the downstream should have an equal diameter straight pipe section of not less than 5D

special attention: if a valve is installed near the upstream of the installation point of the vortex flowmeter, constantly opening and closing the valve will have a great impact on the service life of the flowmeter, and it is very easy to cause permanent damage to the flowmeter. The flowmeter shall not be installed on the very long overhead pipeline as far as possible. After a long time, due to the sagging of the flowmeter, it is very easy to cause the sealing leakage of the flowmeter on the flange. If it has to be installed, the pipeline fastening devices must be set at the upstream and downstream 2D of the flowmeter