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A rotameter, also known as a float flow meter, is a type of flow meter that operates on the principle of variable area. As the liquid flows through the meter’s gauge tube, from bottom to top, the buoyancy of the fluid along with upward forces cause the float to rise. When these forces reach an equilibrium with gravity, the float remains stable, and the flow indication at that point represents the actual flow rate. I. Large measurement errors in rotameters: 1. Due to factors such as long-term use and pipeline vibration, moving parts of the float meter such as the sensing magnet, pointer, counterweight, and rotating magnet become loose, resulting in significant errors. Solution: You can first verify by manually pushing the pointer. First, press the pointer to the RP position and check whether the output is 4mA and whether the flow rate display shows 0%. Then, verify it sequentially according to the scale. If any discrepancies are 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. 2. 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. 3. The relatively large variation in the density of the liquid medium is also a reason for the significant errors. Since, before calibration, the medium is converted to an equivalent density as specified by the user in order to calibrate it using the flow rate of water under standard conditions, any significant change in the density of the medium can cause substantial errors in the measurements. The solution is to substitute the changed medium density into the formula to calculate the error correction coefficient, and then multiply the flow rate measured by the flow meter by this coefficient to obtain the actual flow rate. 4. Incorrect installation: For vertically installed rotameters, they must be kept vertical, with an inclination of no more than 20 degrees; for horizontally installed rotameters, they must also be kept horizontal, with an inclination of no more than 20 degrees. There should be no ferromagnetic objects within 100 mm around the rotameter. The installation location should be far away from valve diameter changes, 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.