E+H mass flow meter
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What are the main reasons why the E+H mass flow meter shows a significantly high value, and how can this be addressed? The fault phenomenon is that when the control valve is opened by 1% of its full stroke, the flow rate reaches 20 t/h. The flow meter is of DN80 type; when the control valve is closed at 0%, the flow meter shows 0, indicating no flow. What causes this phenomenon?
How about using a process line valve with a control valve to test the flow meter? It’s not necessarily a problem with the mass flow meter; simply using a control valve for testing doesn’t allow for a definite determination as to whether there is an issue with the flow meter
When the opening degree of the control valve is zero, it does not mean that no fluid passes through the valve and flow meter, as all valves have a permissible leakage rate, and mass flow meters are equipped with low-signal cutoff functions. The method upstairs can be tried, or it might be applicable to other measuring devices such as level gauges and scales.
Was there any vibration at the scene? Is there enough straight pipe section at the installation location?
You didn’t specify what the flow measurement range is. For mass flow meters, the pipe must be completely filled; it’s also important to avoid any bubbles. Improper installation that results in stress can also cause the flow meter to malfunction.
Don’t consider only the flow meter itself; the entire process pipeline, the medium, and the distances of the straight sections before and after it should also be taken into account in the analysis
Mass flow meters do not require straight sections of pipe before and after them, but care must be taken to avoid any stress being applied during installation. A simple way to check this is to close the valves at both ends, ensuring that the pipe is filled with the medium and the flow rate is 0. You can then check whether the measured value includes density information; it should be close to the actual density of the medium or the reading should be zero in the case of an empty pipe. Turn off the flow for low volumes and see if there are any unusually high flow values. For DN80 pipes, a flow rate of 10 kg/h or less is generally considered acceptable. If the value is too high, perform a zero-point adjustment and check how much the adjusted zero-point differs from the factory-set zero-point; a difference of around 15 to 20 is usually acceptable. If all the above checks show no problems, then it can be confirmed that there is nothing wrong with the flow meter; the issue lies in the process. What is the medium being measured? Is it viscous? It’s not a non-Newtonian fluid, right?
What is the diameter? How much low-flow cut-off should there be for the flow meter? What about the actual zero point?
Is 20t/h stable? It still just jumps to 20 in an instant and then fluctuates?