Reasons for frequent fluctuations in flow rate of target flow meter (4 M3/h)

Reply to 1# bingxuerui with the following content, which might be helpful to you: Causes and solutions for fault phenomena – The discrepancy between actual flow rate and indicated value is due to corrosion, resulting in changes in the float’s flow rate, volume, and maximum diameter； Use corrosion-resistant materials for changes in the inner diameter of conical tubes. If the float size remains the same as before the replacement, it can be converted or recalibrated using the new weight and density ； If the dimensions are also different, recalibration is necessary. If the cylindrical surface of the float’s maximum diameter becomes worn and rough, affecting the measurement values, replace it with a new rotor. Floats made of or lined with engineering plastics may swell, resulting in changes in their maximum diameter and volume. Using floats made of appropriate materials can help to ensure that the actual flow rate matches the indicated value. Foreign substances such as scale and dirt adhering to the float or conical tube should be removed to prevent damage to the inner surface of the conical tube and the cylindrical surface of the float, thus maintaining its original surface roughness. When the actual flow rate does not match the indicated value, adjustments should be made based on the changed physical properties of the fluid. In cases where the actual flow rate differs from the indicated value due to changes in temperature or pressure of gases, steam, or compressible fluids, corrections must be made according to the new conditions. Fluid pulsations or sudden changes in gas pressure can cause fluctuations in the indicated value; in such situations, a buffer tank should be installed or an instrument with a damping mechanism should be used. If bubbles are present in the liquid or liquid droplets are present in the gas, these should be removed. In instruments used for liquids, gas may accumulate in dead corners inside the instrument, affecting the buoyancy of the float component; this issue is particularly significant for instruments handling low flow rates, so the gas must be removed. If the float or pointer moves slowly in response to changes in flow rate, it may be due to foreign particles between the float and the guide shaft or bending of the guide shaft. In such cases, the components should be disassembled and cleaned, foreign substances or accumulated layers removed, and the guide shaft straightened. Bending of the guide shaft is often caused by rapid opening and closing of solenoid valves, which leads to sudden rises in the float’s position; changing the operating mode can help resolve this issue. If the float or pointer still moves slowly despite changes in flow rate, it may be because iron powder or particles have adhered to the magnets in the magnetically coupled float assembly, or because the linkage or pointer is stuck. These issues should be resolved by disassembly and cleaning; during the initial operation phase, the pipes should be thoroughly cleaned using a bypass pipe. A moving linkage with a manual and magnetic coupling for installing a filter in front of the instrument is provided, along with adjustments for areas where jamming may occur. Check whether there are any foreign objects between the rotating shaft and the bearings that could prevent movement; remove such objects or replace the relevant parts. Changes in flow rate can cause the float or pointer to move slowly. Engineering plastic floats and tapered tubes, as well as plastic tube linings, may swell or become stuck due to thermal expansion; in such cases, replace them with corrosion-resistant materials. For media at higher temperatures, avoid using plastic as much as possible and opt for parts made of corrosion-resistant metals. If flow variations cause the float or pointer to move slowly, or if the magnetism of the magnet in magnetic coupling decreases, remove the instrument and move the float up and down by hand to ensure that the pointer and other indicating elements move smoothly accordingly ； If it does not follow or follows unstably, replace the part or re-magnetize it. To prevent a decrease in magnetism, it is prohibited for the two coupling components to collide with each other