Self-operated (after valve) Pressure Control Valve

After throtting by the plug and seat, the before-valve pressure P1 of the process medium is changed into the after-valve pressure P2.Through the control pipeline, P2 is input to the lower diaphragm chamber of the actuator and acts on the topdisc. The acting force producedbalances the reacting force of the spring, determining relative positions of the plug andseat and controling the after-valve pressure.Whenthe after-valve pressure P2 increases, the acting force of P2 that actson the top disc will increase accordingly. At the time, the acting forceon the top disc is higher than the reacting force ofthe spring to make the plug close towards the seat, until the acting force on the top discbalances the reacting force of thespring. At the time, the flow area between the plug and seat is reduced, the flow resistance becomeshigher and P2 isreduced to the set value. Likewise, when the after-valve pressure P2 decreases, the acting direction is reverse to theabove.This is the working principle during the control of after-valve pressure.
When it is necessary to change the set value of after-valve pressure P2, please adjust the adjusting nut.