Answer / senthil r.m

My dear,
In control valve we ll compare the setpoint(operator interference value) and the actual pressure on the line.this deviation is given to the control valve.When the error is positive(means pressure is high),the C/V starts closing and when the error is negative(means pressure is low),the C/V opens and maintains the pressure.
One more thing,why u need to fix the low limit of control valve to open 20%.Depending on the deviation the controller controls the process pressure.
Finally,the controller tuning is must for this control.play with the gain and integral time and deadband to make steady process..

Answer / daxish_02

If pipe size is same before and after so this answer is correct..
basic fundamental behind the general formula that is
pressure=force/area......ok
here pipe size is fixed...ok
assume 20% valve open....than area of pipe cover after the valve is more so we get some pressure..
assume that valve open 40% so area of material flowing through valve increase so pressure decrease after the valve.....

Answer / ashraf

First, know where the valve is.If it is at upstream,(High
pressure line to vessel), then close valve and open vent
valve till pressure reduces to 10 kg. If it is at
Downstream,open the valve.

Answer / g.s.arun

to open the byepass valve ,to reduce the pressure 20kg to 10 kg.

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