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Pneumatic flange hard seal butterfly valve pneumatic head The butterfly plate of Shanghai Yuwang Valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis. The initial position of the valve is determined according to actual needs. National standard, flange connection, with double-acting actuator/single-acting actuator, control mode: switch Type, adjustment type.