Three Common Metal Tube Rotameter Faults

The rotameter is also called a float meter. It is a variable area flowmeter. The liquid flows into the graduated tube of the flow meter. From bottom to top, the buoyancy of the fluid and the upward lift pushes the float to rise, but when it reaches a balance with gravity, the float remains stable and the scale of the flow indicator at this time is the actual bit rate of the stream.

Rotameter sometimes has some faults, and there are three common ones:

1. Metal tube rotameter measurement error is large:

1. Gas Since the fluid is strongly influenced by temperature and pressure, it is recommended to use temperature and pressure compensation to obtain the actual flow rate.

2. Due to many factors such as long-term use and pipeline vibration, the floating flow meter moving parts, such as the detection magnet, needle, counterweight and the magnet rotatedtif, are loose, resulting in big errors. Solution: You can check first by pressing the pointer with your hand. First, press the pointer at the RP position to see if the output is 4mA and the flow rate display is 0%, then check according to the scale in turn. If deviations are found, positional adjustments can be made to the components. Generally, personnel need to adjust, otherwise the position will be lost and it needs to be sent back to the factory for correction.

3. The installation does not meet the requirements: for rotameters installed vertically, keep them vertical, with an angle of inclination not exceeding 20 degrees; for rotameters installed horizontally, keep them horizontal, with an angle of inclination no greater than 20 degrees; There must be no ferromagnetic objects within the 100 mm space. The installation location should be away from the variable diameter hole.e of valve, pump outlet, treatment line swivel, etc. The requirement for a straight pipe section of 250mm after the first 5D should be maintained.

4. The great change in the densities of the liquid medium is also a reason for the great error. Because the meter converts the medium according to the density given by the user before calibration, and converts it to water flow in the calibration state for calibration, so if the density of the medium changes greatly , it will cause a large error in the measurement. The solution is to incorporate the modified average density into the formula, convert it to an error correction coefficient, then multiply the flow rate measured by the flow meter by the coefficient to replace it with the actual flow rate.

Second, the rotameter pointer shakes:

1. Slight pointer shakes: Usually caused by medium fluctuations. he canbe overcome by increasing damping.

2. Moderate pointer jitter: Usually caused by media throughput status. For gas, this is usually caused by unstable fluid operating pressure. A pressure or flow stabilization device can be used to overcome or increase gas damping of the rotameter.

3. Severe needle agitation: mainly due to medium pulsation, unstable air pressure, or the pressure, temperature and flow rate of the gas working state indicated by the user do not correspond to the actual state of the rotameter. Flow meter out of range.

Third, the metal tube rotameter pointer stops at a certain position:

The main reason is that the rotameter rotor is stuck. Typically, when the rotameter is used, the valve opens too quickly, so the rotor quickly hits the cap upwards, causing the deflection.formation and failure of the cap. Lock the rotor. However, it is not excluded that the rotor is blocked because the guide rod of the rotor is not concentric with the stop ring. When processing, remove the counter, remove the deformed cap and reshape it, and check whether it is concentric with the guide rod. If it is not concentric, you can correct it. Yes, in addition, when installing the rotameter, it must be installed vertically or horizontally, and cannot be tilted, otherwise it will easily cause the meter to jam and cause measurement errors.

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