Eight common faults of vortex flowmeters and their solutions

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　　Vortex flow meters are primarily used for measuring the flow rate of fluids in industrial pipelines, including various media such as gases, liquids, and vapors. Intelligent vortex flowmeters are characterized by low pressure loss, a wide measurement range, and high accuracy. When measuring volumetric flow rate under operating conditions, they are hardly affected by parameters such as fluid density, pressure, temperature, and viscosity. Furthermore, the instrument has no moving mechanical parts, thus offering high reliability, low maintenance requirements, and stable instrument parameters over the long term. This article addresses the eight most common faults that occur during the use of vortex flowmeters, and provides corresponding inspection methods and solutions, in the hope of bringing convenience to users. 　　One of the eight common faults – flow is present in the pipeline but no signal is output, or the instantaneous flow rate is not displayed. First, check whether the circuit wiring and power voltage are correct; confirm that there is indeed flow in the pipeline, and that it is above the minimum detectable flow rate; check whether the setting for the low-flow cutoff value is too high. If the circuit wiring and power voltage are correct, turn the sensitivity potentiometer and the amplification factor potentiometer clockwise to the lowest positions. If no flow is still indicated and there is no change in the cumulative amount, it indicates a problem with the circuit board, and the amplifier board needs to be replaced. If a signal is output, it is necessary to check whether the flow rate of the medium in the pipeline exceeds the measurable range of the vortex flow sensor. If the medium flow rate is within the measurable range, it means that the sensitivity of the sensor’s sensing element is too low, and its sensitivity needs to be adjusted again. Check whether the sensor is functional or not. Remove the two leads of the sensor from the amplifier board, and use a multimeter to measure the resistance between these two leads as well as the resistance of each lead relative to the housing. Both values should be greater than 2MΩ; otherwise, the sensor needs to be replaced. If there is no problem with the sensor, then check whether the pressure transmitter and the platinum resistance thermometer are damaged. If neither of them is damaged, it can be concluded that the intelligent flow meter is defective. 　　One of the eight common faults – signal output is detected when there is no flow of medium in the pipeline, or an instantaneous flow value is shown. 1. First, confirm that indeed there is no flow or disturbance of medium in the pipeline, and check whether the vibration level in the pipeline is too high. If the vibration is severe, follow these steps to reduce it: Install pipe supports 2D downstream of the flow meter; install flexible hoses as long as the requirements for a straight pipe section are met. 2. Adjust the sensitivity potentiometer counterclockwise until no signal is output or the instantaneous flow value returns to zero. When adjusting the potentiometer, it should be done as slowly as possible; pause for more than 10 seconds after each adjustment of 5 degrees to check whether the output returns to zero. 　　One of the eight common faults – irregular, unstable signal output or unstable instantaneous flow rate. First, check whether the flow rate of the medium in the pipeline exceeds the measurable range of the sensor. If the flow rate is within the measurable range, verify that the straight sections before and after the sensor meet the requirements, and ensure that the medium in the pipeline is flowing steadily, with no two-phase flow or pulsating flow present. Check whether the vibration level in the pipeline is too high; if so, address it using the methods outlined in Fault 2. Examine whether there are strong electrical interference signals around the instrument; if so, enhance shielding and grounding. Check whether the sensor is contaminated, damp, damaged, or has poor wire connections; if so, clean or replace the sensor and tighten the wires. Verify whether the sensor is installed concentrically or whether the gasket protrudes into the pipeline; if there are issues with the installation, adjust the inner diameter of the gasket. Check the sensitivity of the sensor and adjust it as necessary. Ensure that the process flow is stable, and adjust the installation position accordingly. Check for any obstructions wrapped around the sensor. Look for cavitation in the pipeline; if present, reduce the flow rate and increase the pressure inside the pipeline. 　　One of the eight major faults – large measurement error. First, check whether the supply voltage to the flow meter is too high; also examine whether there is any drift in the instrument’s analog conversion circuit or if the range settings are incorrect. If so, adjust the zero and range markings accordingly. 　　Check for issues such as 1, 2, and 5 listed in Fault 3; verify whether the gauge has exceeded its calibration period; check for leaks in the pipes. 　　One of the eight major faults – leakage in the measurement tube: Check whether the pressure inside the tube is too high; verify that the selected nominal pressure is correct; if not, use a sensor with a higher nominal pressure rating. Check whether the seals are damaged; also check whether the sensor is corroded, and if so, take measures to prevent corrosion and provide protection. 　　One of the eight major faults – abnormal whistling sound from the sensor. Check whether the flow rate is too high, causing intense vibration; if so, adjust the flow rate or replace it with a sensor with a larger diameter. Check for cavitation; if present, adjust the flow rate and increase the liquid flow pressure. Also check whether the component in question is loose. 　　One of the eight common faults – incorrect temperature display by the instrument. Check whether the wiring is incorrect or if there are any breaks in the wires; its resistance should be around 1080 ohms at room temperature. Consult the manufacturer based on the measured values. 　　One of the eight major faults – incorrect pressure display by the gauge. Check whether the wiring is incorrect or if there are any breaks in the wires; at room temperature, its resistance should be around 5000 ohms. Consult the manufacturer based on the measurements taken.