Problems with Abb electromagnetic flowmeters
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Our plant’s sedimentation tank is equipped with a flow meter for the inlet water – an ABB electromagnetic flow meter. When the pump starts to supply water, the gauge shows a flow rate, but the value indicated is negative. By checking the curves on the DCS system, it was found that this situation occurs: the flow rate is negative for a while, then it returns to a positive value after some time. When the pump stops and is started again, the flow rate becomes negative once more. Has anyone encountered this problem?
Could it be that they were dissatisfied from the start?
There is a control valve in front of the flow meter; with the same opening degree, the flow rate can sometimes be positive and sometimes negative.
I have never encountered this situation. If it is confirmed that the pipeline is full and the flow rate is positive with no backflow, choosing to display the absolute value will ensure that the value remains positive throughout
Set the header flow direction to forward; it seems you have set it to bidirectional
First, consider whether it is possible for the actual fluid to experience backflow after the pump is started. If that is not possible, then check whether, after the pump starts, a two-phase flow of gas and liquid may occur in the pipeline, resulting in false readings on the gauge; normal readings are restored once the amount of bubbles in the fluid decreases. Therefore, it is possible to try turning off the header empty pipe alarm function and then observe whether reverse flow will still appear on the display.