The cumulative value of the mass flow meter suddenly decreases
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The cumulative value on the display of a Yokogawa mass flow meter in our unit suddenly dropped from over 7,000 to over 4,000. Could anyone explain what’s causing this? Thank you
How can the cumulative flow decrease? Is there a reverse flow, with negative flow accumulating?
Before putting the mass flow meter into use, the medium is filled in, the valves at both ends are closed, and zero-point adjustment is performed. After commissioning, perform a low-flow cut-off.
This post was last edited by liaifeng on 2020-7-30 08:50. 1. Are there any relevant alarm alerts on the field panel or DCS? 2. Is your mass flow meter of the balanced type? 3. What medium? Is there any vaporization occurring? 4. Is the operating condition of the flow meter within its operating range?
Check the configuration of the flow direction and accumulation amount to ensure it is set to two-way, with positive values for accumulation and negative values for depletion.
Cumulative flow is achieved by performing additive counting on pulse signals; if the reverse flow measurement function is not enabled, the cumulative value does not decrease but only increases, and it resets to zero and starts counting over again once the measured value exceeds its limit. This flow meter is either measuring reverse flow, is faulty, or has been reset by someone
This mass flow meter is used in the recycling system for loading substances onto vehicles; the medium in question is crude benzene. After loading, the vehicle drives away, so there should be no risk of backflow. Although the cumulative amount has dropped from over 7,000 to over 4,000 at present, according to feedback from the operators, the cumulative amount can start building up again from over 4,000, and the values remain fairly accurate. So what needs to be clarified now is why it suddenly dropped from over 7,000 to over 4,000.