Guidance on Solving Common Faults of Vortex Flow Meters

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1. The indicated error is too large and the repeatability is too high; the cause is damage to the vortex generator of the primary element； The length of the straight sections upstream and downstream is insufficient ； The instrument constant K was set incorrectly ； The probe is severely contaminated ； The fluid disturbance inside the pipeline is too severe. The solution is to replace the vortex generator ； Change the installation location ； Re-measurement calibration to obtain the correct instrument constant K ； Clean the probe ； Change the installation location to increase inlet pressure. ? 2. Signal output is present when there is no traffic. The cause is interference signals introduced due to poor shielding or grounding of the instrument’s wiring ； There are high-voltage equipment or power cables nearby the instrument, causing interference ； The pipeline vibrated violently. The solution is to strengthen the lead shielding and ensure proper grounding of the circuits ； Keep the instrument away from sources of interference ； High jump trigger level or shock absorption. 3. The expansion of the flow rate lower limit is limited; a flow display and accumulation instrument that allows for the setting of a flow compensation coefficient should be used, with software programming employed to enable the expansion of the flow rate lower limit. Taking the triangular prism vortex generator as an example, with a Reynolds number range of 2×104 to 7×106, corrections should be made when measuring low flow rates in order to extend the lower flow limit to 5×103. Based on the theoretical compensation correction coefficients in the Reynolds number range of 5×103 to 2×104, the lower limit of flow rate is expanded and the measurement error of compensated flow rate is reduced. 4. No display on the secondary instrument after power is applied? The possible causes are incorrect power wiring or an open circuit in the power supply ； The wiring voltage is greater than 220V, causing the electric furnace to be damaged ； The supply voltage does not match the voltage required by the instrument ； Sensor failure or amplifier board failure ； Therefore, the flow rate within the pipeline is too low, or there is no flow at all in the pipeline. The solution is to check the wiring and ensure it is connected properly ； If the burn damage indicates a faulty component, replace it with an original part ； Provide the power supply as required ； Replace faulty components of the secondary instruments ； Adjust the pipeline flow rate. 5. The instrument constant K changes depending on the medium being used. When a vortex flow sensor is used to measure liquid flow, water should be used to calibrate the value of K; when measuring gases and vapors, gases should be used for calibrating K. Although in principle the instrument constant K has nothing to do with the properties of the medium being measured, differences exist among various manufacturers due to the manufacturing processes used for sensors; as a result, the K values for different fluids can vary slightly. Therefore, when using different media, calibration with an equivalent medium should be performed to obtain the instrument constant K value. At the same time, when the medium temperature is above 150°C, the instrument constant K value should also be corrected. ? 6. The flow rate is inaccurate and differs significantly from the process parameters; the reason is an error in entering the process parameters ； The instrument range does not meet the actual flow requirements. The solution is: enter the instrument parameters correctly ； Adjust the process or select instruments suitable for the actual flow range. 7. Abnormal output of remote transmission signals; the reason analyzed is that if frequency or pulse signals are being transmitted, the receiving circuit and the output circuit are not compatible ； If it is a (4–20) mA current output, the flow rate setting range does not correspond one-to-one with the output current. The solution is to use external electrical components (such as resistors with a certain resistance value connected in series), so as to ensure good compatibility between the output and input circuits ； During parameter setting, the flow rate upper and lower limit values correspond one-to-one with 4mA and 20mA. 8. After the instrument has been in use for a period of time, the error may deviate from the normal range. Since industrial fluid media often contain various impurities, the sensor should be cleaned within the specified time frame, depending on the specific circumstances.