Common Faults and Treatment Measures of Vortex Flowmeter

Common faults

① Long-term inaccurate indication: It may be caused by damage to the vortex flowmeter sensor or electronic components. The corresponding parts need to be checked and replaced.

② No indication at all: It may be caused by power failure or signal line problem. Check whether the power supply and signal line are normal.

③ The indication fluctuates over a large range and cannot be read: This may be caused by changes in the fluid properties of the vortex flowmeter or excessive sensor sensitivity. The sensor sensitivity needs to be adjusted or the fluid conditions need to be optimized.

④ The indication does not return to zero: It may be caused by sensor zero drift. The problem can be solved by recalibration.

⑤ No indication at low flow: This may be caused by low fluid viscosity or density. The fluid properties need to be checked and corresponding measures taken.

⑥ The indication is OK at high flow, but inaccurate at low flow: This may be caused by improper vortex flowmeter sensor range selection. The appropriate range needs to be reselected.

⑦ The indication changes cannot keep up with the flow change: It may be caused by the vortex flowmeter not responding fast enough. The response speed can be improved by optimizing fluid conditions or improving sensor design.

⑧ The K factor of the instrument cannot be determined, and multiple data are inconsistent: This may be caused by improper measurement principles or data processing methods. It is necessary to carefully check the measurement principles and data processing methods to ensure the accuracy of the K factor.

Possible problems

a. Selection problem. Due to changes in process conditions, the vortex flowmeter sensor caliber selection may be improper, resulting in an actual selection that is too large, affecting the measurement accuracy. To improve accuracy, the smallest possible caliber should be selected. This may be related to problems ①, ③, and ⑥. For example, a vortex pipeline is designed for use by multiple devices, but the actual flow rate is reduced, resulting in the original design selection caliber being too large, affecting the measurement at low flow rates. At this time, the indication accuracy can be improved by re-setting the parameters.

b. Installation problem. The length of the straight pipe section in front of the vortex flowmeter sensor is not enough, which will also affect the measurement accuracy. This is mainly related to problem ①, and it is necessary to ensure that the length of the straight pipe section meets the requirements.

c. Parameter setting problem. Parameter errors may cause inaccurate instrument indications, such as incorrect calculation of the full-scale frequency of the secondary instrument. This will affect the long-term stability of the indication and the accuracy of the readings. The solution is to re-determine the parameters and calibrate.

d. Secondary instrument failure. This includes circuit board disconnection, range setting or K-factor setting display failure, etc., which makes it impossible to determine the range and K-factor. This is mainly related to problems ① and ②, and the corresponding faults need to be repaired.

e. Line connection problem. Although the line connection appears to be good on the surface, there may actually be problems such as loose joints of the vortex flowmeter or fastening screws fastened on the line skin, resulting in circuit interruption. This is mainly related to problem ②, which requires careful inspection and repair.

f. Connection problem with subsequent instruments. Due to problems or repairs of subsequent vortex flowmeters, the mA output circuit of the secondary instrument may be interrupted. This is mainly related to problem ②, and it is necessary to check and ensure that the connection is normal.

g. Secondary instrument flat-axis cable failure. Long-term operation and dust influence may cause flat-axis cable failure, and the flat-axis wire needs to be cleaned or replaced to solve the problem.

h. Header problem. Due to the loosening of the fixing screws of the vortex flowmeter head coil, the head may sink, the pointer and the case may rub more, and the indication accuracy may be affected. The head needs to be adjusted and re-fixed to solve this problem.

i. Use environment problem. Especially for the sensor part of the vortex flowmeter in the ground well, the circuit board is damp due to the high humidity, which will affect the measurement accuracy. The solution is to use a split flowmeter to adapt to this environment.

j. On-site adjustment problem. Improper on-site vibration noise balance adjustment and sensitivity adjustment, or changes in on-site conditions after adjustment, may cause indication problems. It is necessary to use an oscilloscope and readjust it in combination with the process operation to solve this problem.