When the pressure go into the valve control cavity ,septa velum press down and close the valve routeway .When the pressure go to the pipe, valve control will rise ,the valve routeway will open .

• 当压力介质进入阀门控制腔，隔膜下压，关闭阀门通道，当控制腔压力排向大气或下游管道，隔膜上升，阀门通道被打开。