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1. The pointer of a metal rotor flowmeter stops in a certain position and does not move. The main reason for this is that the float of the float flowmeter gets stuck. Generally, this occurs because the valve is opened too quickly when using the metal rotor, causing the float to rush upward and strike the stopper, which in turn leads to deformation of the stopper and trapping of the float. However, it is also possible that the float gets stuck due to the float guide rod and the stop ring not being aligned. During processing, the gauge can be removed, the deformed stopper can be taken off and reshaped, and it should be checked whether it is concentric with the guide rod; if not, correction can be made. Then the float should be installed, and the float should be pushed by hand to ensure that it moves up and down smoothly without any obstruction. Additionally, when installing a float flow meter, it must be installed vertically or horizontally – it cannot be tilted, as this can also lead to obstruction of the gauge and cause measurement errors. 2. Trembling of the pointer in metal rotor flowmeters 1. Mild pointer trembling: Usually caused by fluctuations in the medium; this can be addressed by increasing damping. 2. Moderate pointer jitter: This is usually caused by the flow conditions of the medium; in the case of gases, it is often due to unstable operating pressure of the medium. Pressure or flow stabilizing devices can be used to overcome this issue, or the gas damping in the metal rotor flow meter can be increased. 3. Severe pointer oscillation: This is mainly caused by medium pulsations, unstable air pressure, or differences between the pressure, temperature, and flow rate specified by the user for gas operation and the actual conditions of the metal rotor flow meter, resulting in the float flow meter operating outside its range. III. Large measurement errors in metal rotor flowmeters 1. Improper installation (1) For vertically installed float flowmeters, they must be kept vertical, with an inclination of no more than 20 degrees. (2) For horizontally installed float flowmeters, they must be kept horizontal, with an inclination of no more than 20 degrees. (3) There should be no ferromagnetic objects within 100 mm around the float flowmeter. (4) The installation location should be far away from valve reducers, pump outlets, and bends in the process pipelines. The requirement of a 5D front section and a 250 mm straight pipe section at the back must be maintained. 2. Large changes in the density of the liquid medium are also a cause of significant errors. Since, before calibration, the medium is converted to a density specified by the user in order to calibrate it using the flow rate of water under standard conditions, any significant change in the medium’s density can cause large errors in the measurements. The solution is to substitute the altered medium density into the formula to calculate an error correction factor, and then multiply the flow rate measured by the flow meter by this factor to obtain the actual flow rate. 3. Since gas media are greatly affected by temperature and pressure, it is recommended to use temperature and pressure compensation to obtain an accurate flow rate. 4. Prolonged use and pipe vibrations, among other factors, cause the moving parts of the float flow meter such as the sensing magnet, pointer, counterweight, and rotating magnet to become loose, resulting in significant errors. Solution: You can first verify by manually pushing the pointer. First, place the pointer at the RP position and check whether the output is 4 mA and whether the flow display shows 0%. Then verify it step by step along the scale. If any discrepancy is found, the position of the component can be adjusted. It is generally required that professionals make adjustments; otherwise, the position will be lost and it will be necessary to return to the manufacturer for correction. Flow metering is one of the components of measurement science and technology, and it is closely related to the national economy, national defense construction, and scientific research. Doing this job well plays an important role in ensuring product quality, improving production efficiency, and promoting the development of science and technology. Especially in today’s era of energy crises and an increasing degree of automation in industrial production, the significance and role of flow meters in the national economy have become even more evident.