Kolon MFC300F mass flow meter, no display issues?
Thread Content
The MFC300F mass flow meter in Cologne’s tank area was used to measure the propylene product flowing through the process. It displayed normal readings after it was put into operation, but stopped showing readings after the control valve was adjusted; it was determined that this was caused by a gas-liquid two-phase flow, and management ordered that it be modified. The solution we adopted was to fully open the control valve and manually adjust the hand valve behind the flow meter; only when the opening degree of the hand valve was around 10% did the flow meter start to show a reading. By maintaining the position of the manual valve, the valve can be adjusted within the range of 70% to 100%. The cause of this problem is 1. The incorrect design of the position of the control valve, which leads to a mixture of gas and liquid in the medium? 2. Issues with flow meter selection?
The flow meter was chosen to be too large, or the process parameters were not determined accurately.
The mass flow meter is installed in front of the control valve to prevent abnormal operation of the flow meter caused by the gas-liquid mixture that arises after the control valve operates.
It may involve issues related to the matching of valve and instrument ranges; it’s best to compare the design flow rates of the valve and the flow meter: lol
Should the flow meter be placed before or after the control valve?
Insufficient back pressure causes the medium to exist in a gas-liquid mixture at the flow meter; by closing the manual valve to 10%, the pressure at the flow meter is increased. This is a problem related to process design – no matter how the valves are selected or installed, it is not possible to increase the pressure in the process pipelines.
Check whether low-flow cutoff is set; if so, it may be that the flow meter selected is too large, and the flow rate is not low enough to reach the cutoff point. If it isn’t set, then there is a fault with the flow meter; because even in the gas-liquid two-phase state, the measurement will only be inaccurate, but there shouldn’t be no flow at all. It’s best to ask the manufacturer.
Mass flow meters have very high sensitivity and precision; accuracy is a different matter – as long as there is some flow, the reading will still change slightly. Sometimes pipeline vibration, pressure fluctuations at the inlet, and a small amount of gas can also cause the flow meter to drift