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Use and Maintenance of Vortex Flow Meters: The vortex flow sensor is powered by 12VDC from a secondary instrument; it uses piezoelectric crystal elements to detect the frequency of vortex separation. The probe installed inside the cylinder detects the pressure pulses generated on both sides of the back of the cylinder as a result of the vortices. The piezoelectric crystal elements embedded within the probe generate alternating charges in response to these stress forces, and after processing by the sensor, these signals are transmitted as pulses of a certain amplitude to the secondary instrument. This pulse signal is proportional to the flow rate passing through the pipe, and this proportional relationship is determined by the K factor of the sensor. The K factor is typically calibrated by the manufacturer, and it indicates the number of pulses emitted by the sensor for each unit of flow rate through the pipe. The secondary instrument is a flow display device based on the SK series microcontroller 908. Upon receiving this pulse signal, it displays the instantaneous flow rate using an analog ammeter, while simultaneously showing the cumulative flow rate or cumulative time via an 8-digit digital display. It can also output a 4–20 mA or 0–10 mA signal for use with regulators or recorders. The secondary meter has its parameters set based on the K coefficient of the sensor and the flow range. The main problem is the issue with vortex flowmeters. The main issues are: ① Indications that are inaccurate over the long term ； ②No instructions at all ； ③Indicates large fluctuations; no reading possible ； ④Indicate not to return to zero ； ⑤No indication at low flow rates ； ⑧The indication is okay at high flow rates, but inaccurate at low flow rates ； ⑦The indication fails to keep up when the flow rate changes ； ⑧The K coefficient for the instrument cannot be determined, as there are inconsistencies in various sources. Analysis and resolution of major issues: The analysis and resolution of these issues are complicated due to the intricate nature of the problems. Issues exist to varying degrees in aspects such as design and installation, parameter setting, daily maintenance, and the operating environment; many of these issues are interrelated. Additionally, resolving some issues requires waiting for certain conditions to be met during the operation process, which adds significant difficulty to their resolution. Some issues are caused by a combination of different factors, with some of those factors being related to multiple different issues. Summarizing the main reasons for these problems, they mainly relate to the following aspects: (1) Issues with selection. Some vortex flowmeter sensors, either due to the choice of diameter or as a result of changes in manufacturing conditions after the initial design, end up having a diameter that is too large; in such cases, it is necessary to choose the smallest possible diameter in order to improve measurement accuracy. The reasons for this are mainly related to issues ①, ③, and ⑥. For example, a vortex street pipeline is designed to serve several devices; since some of the equipment in the process system is not used at times, the actual flow rate in use is reduced. As a result, the diameter selected in the original design is too large, which raises the lower limit of the flow rate that can be measured. The gauge cannot provide accurate readings when the flow rate is low, but it still functions properly when the flow rate is high, as it would be too difficult to make modifications in such cases (sometimes, changes in process conditions are only temporary). The indication accuracy can be improved by adjusting the parameters. (2) Issues with installation. Mainly, the length of the straight section in front of the sensor is insufficient, which affects the measurement accuracy; this issue is primarily related to problem #1. (3) Reasons for the parameter tuning direction. Due to incorrect parameters, the instrument readings are inaccurate. These parameter errors result in an incorrect calculation of the full-scale frequency of the secondary instrument; the causes of this are mainly related to issues ① and ③. A significant difference in the full-scale frequency leads to inaccurate readings over time; when the actual full-scale frequency is much higher than the calculated value, the readings fluctuate greatly and become unreadable. Moreover, inconsistencies in the parameters listed in the documentation affect the final determination of these parameters. This issue was resolved by performing re-calibration and making comparisons between different values. (4) Secondary instrument failure. There are many faults in this area, including broken wires in the primary instrument circuit boards, faulty display of individual bits related to range setting, and faulty display of individual bits related to K-factor setting, which makes it impossible to determine the range setting and the K-factor value. These issues are mainly related to problems ① and ②. The problem was resolved by fixing the corresponding fault. (5) Four-way circuit connection issue. On the surface, the wiring in some circuits appears to be properly connected; however, upon closer inspection, it is found that some connectors are actually loose, resulting in a disruption of the circuit. In other cases, although the connectors are tightly fitted, issues with the auxiliary wires cause the fastening screws to tighten against the wire insulation, which also leads to a disruption of the circuit. These problems are mainly related to issue #2. The corresponding wiring issues have been resolved, and the existing problems have also been addressed. (6) Connection issues between secondary instruments and subsequent instruments. Due to issues with the subsequent instruments or maintenance work on those instruments, the mA output circuit of the secondary instrument is interrupted. For this type of secondary instrument, this issue is mainly related to problem #2. Especially for subsequent recorders, when the recorder is permanently damaged and cannot be repaired, it is essential to short-circuit the output of the secondary instrument. (7) The circuit shows no indication at all due to a fault in the flat-axis cable of the secondary instrument. Due to long-term operation and the impact of dust, faults occurred in the flat cable; the problem was resolved by cleaning or replacing the flat cable wires. (8) For issue No. 7, it was mainly due to loose fixing screws of the gauge coil in the secondary instrument, which caused the gauge head to sink; this led to excessive friction between the pointer and the gauge casing, resulting in impaired operation. The problem was resolved by adjusting the gauge head and re-fixing it. (9) Environmental issues related to use. Especially the sensor part installed in the ground well suffers from moisture on the circuit boards due to high environmental humidity; this issue is mainly related to problems ② and ②. Through appropriate technical improvements, the probes of some sensors that operate in high humidity environments were separated from their conversion units, and separate-type sensors were used as a result; this improved the working conditions, and these instruments are now functioning well. (10) Due to poor on-site calibration, or due to further changes in the actual conditions after calibration. Problems with the readings are caused by inadequate adjustment of the on-site vibration and noise levels as well as sensitivity settings, or by further changes in the on-site conditions after operation for a while following such adjustments; these reasons are mainly related to issues ④ and ⑤. Use an oscilloscope, and adjust again by taking into account the operation conditions of the process. (11) Question ⑧ was raised separately because it has had a significant impact on the analysis and resolution of the issue for a long time. Due to the lack of conditions for calibrating the K coefficient, this coefficient could only be determined based on the data provided by the manufacturer. However, various changes within the manufacturer itself led to inconsistencies in the K coefficients given in those documents, which hindered the resolution of the issue. By seeking conditions for re-calibration, or through repeated modifications and comparisons, unified instrument parameters were finally determined. Summary: (1) Since the determination of the K coefficient is extremely important in the entire process related to vortex flow meters, its accuracy directly affects the precision of the measurement system. Factors such as the replacement of components in the instrument and wear and tear on the process pipelines can also influence the K coefficient. Enterprises lack the means and capabilities for calibration; they can only send the devices for calibration. Due to the demands of ongoing processes, it takes 5 to 6 days to remove the vortex flow meters from the pipelines for calibration, which is difficult to accommodate within the constraints of industrial operations, thus making it impossible to determine the K coefficient. This year, through modifications to the flow meters, the conditions for calibrating vortex flowmeters of smaller diameters have been established; however, such methods are still ineffective for vortex flowmeters of larger diameters. In the future, it is necessary to employ on-site calibration techniques for vortex flowmeters, using standard frequencies and portable ultrasonic flowmeters to measure the instantaneous flow rate in the pipeline as well as the pulse output frequency of the sensor, so as to calculate the K coefficient on-site. (2) The probes of vortex flowmeters should be cleaned regularly. During inspections, it was found that the detection holes of some probes were blocked by dirt or even covered with plastic sheets, which affected accurate measurement. (3) Regularly check the grounding and shielding to eliminate external interference. Sometimes, indication problems are caused by interference. (4) Probes installed in humid environments should be dried regularly or treated to prevent moisture absorption. Since the probe itself is not treated to be moisture-resistant, it suffers from impaired performance when exposed to moisture. (5) Sufficient attention should be paid to the management of instrument data to facilitate future work.