Problems with elliptical gear flowmeters
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We have a project requirement that the elliptical gear flow meter must output a 4-20mA signal; therefore I added a flow accumulation device. However, the reading on the flow meter’s dial does not match the output signal. Could anyone with expertise give me some advice? It’s urgent
In this situation, you need to first figure out which traffic is the correct one. The comparison method can be used, by measuring the flow rate with other flowmeters for comparison, or the direct weighing method can be employed to calibrate the cumulative flow rate. Determine specific action plans after understanding the accuracy of the flowmeter and accumulator. If it is a transmission error of the flow meter, the zero point and range of the flow meter can be adjusted (in general, the transmission unit of an elliptical flow meter converts the rotation speed into a frequency signal, which is then converted into a 4–20 mA standard signal). If it is an accumulator error, a standard signal can be input for calibration.
I’ve taken a look; what’s there on site is correct, and the flow meter has also been calibrated and works properly. The problem is that the transmission gear inside the flow meter vibrates as it moves, and this might be causing the inaccurate readings. I’m not sure how to fix it though
Is the pressure in the system pipelines not very stable? Another possibility is that there is dirt between the gears, causing jamming as they rotate. . . If it is external vibration, it should not cause significant interference to its measurement. . . It is recommended that you analyze the condition of the process medium more closely. . Or clean the gears. . . .
If the installation is done horizontally, the accuracy of these measurements will decrease. A few days ago I installed it horizontally, but the person from the manufacturer suggested that it should be installed vertically, as this results in higher accuracy and a longer service life. I used pulse counting; I haven’t used it yet, so I can’t say if there are any problems.
The poster said that the setup on-site is correct, so the fluctuation of the flow meter should not affect the measurements. It might be necessary to check whether the 4-20mA signal output by the flow meter does not match the settings within the totalizer, which could lead to discrepancies in the displayed values. If the flow meter outputs a flow signal, then the display device must be set to the same range as that of the flow meter; only in this case will the outputs be consistent. Otherwise, it means that the output from the on-site instrument does not correspond to the cumulative value generated by the flow meter.
Converting pulses to analog signals should also be linear, right? If there is shaking, consider the following: 1 Whether the number of filter elements is insufficient, resulting in particles in the fluid; 2 Whether it is in a vertical configuration with the fluid flowing from bottom to top
1. First of all, whether an elliptical gear flow meter measures correctly has nothing to do with the readings not matching； 2. Is the reading incorrect due to an accumulated value, or is it the instantaneous flow rate that is incorrect? 3. Incorrect readings are quite normal. The flow meter itself only provides pulse output; therefore, if the parameters of the integrator are not set correctly, or if the wrong integrator is used, the signals may not be compatible, which will inevitably lead to errors ； 4. So, it mainly lies in the integrator. Consult the manufacturer to determine whether the flow meter’s output signal is compatible with the integrator Is there a problem with the parameter settings? The processing of the input signal is crucial.
Meters should use pulse output; it is normal for there to be errors in the instantaneous signals.