Control valve
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Ammonia flow control valve (model DN20-300LB): it is not possible to adjust the flow rate to 8 Nm3/h. The pressure before the valve is 0.5 MPa, and the pressure after the valve is 0.15 MPa. Seeking expert assistance
Is it impossible to adjust because the control valve has failed, or because the setting is not correct (too high? too low?). What is also the Cv value of this valve?
It cannot be adjusted; an opening of 1% already exceeds the range
Could the poster describe the operating conditions before and after the valve, as well as the adjustment requirements for the valve?
The pressure before the valve is 0.5 MPa(G), the pressure after the valve is 0.16 MPa(G), and the inner diameter of the valve is very small. The valve spool is also very small; it handles ammonia gas, and even an opening degree of 1% exceeds the range limit
Turn down the front manual valve of the control valve a bit
Consider the coordinated adjustment of other valves on the same branch in the system, or the adjustment via a bypass line as mentioned in point 4#
The actual opening degree is definitely more than 1%, otherwise the valve seats must be damaged