Packing seal refers to the dynamic sealing device that produces compression force between packing and rotating parts and fixing parts through pretightening or self-tightening action of medium pressure. Also known as "stuffing box seal". There are many structural forms, mainly composed of packing, packing box and packing fixing parts
Under the action of fluid pressure flowing in one direction, the disc opens; When the fluid flows in the opposite direction, the self-coincidence disc of the fluid pressure and the disc acts on the seat, thus cutting off the flow.