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Metal tube rotameter error big solution

Metal tube rotameter error big solution

  • May 19,2020.

A flowmeter is an instrument for measuring the linear, nonlinear, mass or volume flow of a liquid or gas.A good flowmeter selection is based on a clear understanding of specific application requirements.Therefore, take time to fully evaluate the process fluid and overall installation properties.When choosing flow timing, intangible factors such as the familiarity of personnel in a specific plant, their experience in calibration and maintenance, the availability of spare parts and the average time between failures should be considered.It is recommended that the installation cost be calculated after these steps are taken.* a common flub in flow measurement is to reverse the sequence of steps: instead of choosing the sensor that works, you try to justify using a cheaper product.Those cheap purchases can become expensive facilities

Common problems:

I. The measurement error of material tube rotameter is large:

1. As the gas medium is greatly affected by temperature and pressure, it is suggested to use temperature and pressure compensation to obtain the real flow rate.

2. Due to long-term use and vibration of pipeline and other factors, floating flowmeter sensor magnetic steel, pointer, counterweight, rotating magnetic steel and other moving parts become loose, resulting in large errors.Solution: you can verify this by pushing the pointer by hand.First, press the pointer in the RP position to see whether the output is 4mA and the flow rate is 0%. Then, verify it according to the scale.If any discrepancy is found, the position of the parts can be adjusted.Generally, professional personnel are required to adjust, otherwise the position will be lost, and the manufacturer should be returned for correction.

3. The installation does not meet the requirements: for the vertical installation of the rotameter to maintain a vertical Angle of no more than 20 degrees;For the horizontal installation of the rotameter to maintain the level, the dip Angle is not greater than 20 degrees;There shall be no ferromagnetic objects in the 100mm space around the rotameter.The installation position should be far away from valve reducer, pump outlet, process pipeline turning port, etc.Maintain the requirements of the first 5D and the second 250mm straight section.

4. The large density variation of liquid medium is also a reason for the large error.Before calibration, the meter will convert the medium to the density given by the user, and then calibrate the water flow in the calibration state. Therefore, if the medium density changes greatly, it will cause great errors in the measurement.The solution is to change the media density into the formula, into the error correction coefficient, and then the flow rate measured by the flowmeter multiplied by the coefficient into the real flow rate.

II. Rotameter pointer jitter:

1. Violent pointer jitter: mainly due to the pulsation of the medium, pressure instability or the pressure, temperature and flow rate of the gas operation state given by the user are not consistent with the actual state of the rotameter, and there is a big difference resulting in the over-range of the rotameter.2. Slight pointer jitter: generally caused by medium fluctuation.This can be overcome by increasing the damping.3. Moderate pointer jitter: generally due to the media flow state.For the gas generally due to the medium operating pressure instability.The gas damping of the rotameter can be overcome or increased by means of a pressure stabilizing or flow stabilizing device.

III. The pointer of the rotameter stops at a certain position and does not move:

The main reason is that the rotameter's rotor is stuck.Generally, because the rotameter is used to open the valve too fast, so that the rotor quickly upward impact stop, causing the stop deformation and the rotor stuck.However, it is not excluded that the rotor is stuck because the rotor guide bar is different from the stop ring.Processing instrument can be removed, the deformation of plastic surgery to stop off, and check whether with guide bar work, such as different heart can be calibrated, then the rotor installed, push the rotor, feeling the rotor unimpeded card can be up and down, in addition, the rotor flowmeter installation must be vertical or horizontal installation, cannot tilt, otherwise easy to cause the card table, and also brings to the measurement error.

NONCON material tube float flow meter

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