The valve plays an important role in cutting off and throttling the medium in the pipe in which it is located. As an extremely important cut-off valve, the seal is to apply torque to the stem, the stem in the axial direction to the disc pressure, so that the disc sealing surface and the seat sealing surface closely fit, to prevent the media along the sealing surface gap leakage.
The sealing pair of the cut-off valve is composed of the disc sealing surface and the seat sealing surface, and the stem is driven by the valve stem to vertical movement along the center line of the seat. Closing valve opening and closing process of a small height, easy flow of adjustment, and manufacturing maintenance convenience, the scope of application of pressure wide.
Compared with the other commonly used truncation valve one by one valve in industrial production, the cut-off valve is simpler than the former, which is easier to manufacture and repair. From the service life, the cut-off valve sealing surface is not easy to wear and abrasion, valve opening and closing process of valve and _ seat between the sealing surface has no relative sliding, so the wear and tear of the sealing surface is small, so the use of the seal to improve the life of the valve in the whole closed process of the valve flap travel small, the height of the relatively small valve. The disadvantage of the cut-off valve is that the opening and closing torque is large and difficult to achieve fast opening and closing, because the valve body flow is more tortuous, fluid flow resistance is large, resulting in fluid power in the pipeline loss of greater.