The valve is important to cut off and throttle the medium in the pipeline. Cut-off valve as an extremely important cut-off type valve, its seal is by exerting torque on the stem, the valve stem in the axial direction to the disc pressure, so that the disc sealing surface and the seat sealing surface tightly fitting, prevent the media along the sealing surface gap leakage.
The sealing pair of the cut-off valve consists of the disc sealing surface and the sealing surface of the seat, and the valve STEM drives the disc to move vertically along the centerline of the seat. Cut-off valve opening in the process of a small height, easy flow adjustment, and manufacturing maintenance convenience, the pressure is wide range.
Compared with the other commonly used truncation type valves in industrial production, the cut-off valve is simpler and easier to manufacture and maintenance than the former. From the service life, the cut-off valve sealing surface is not easy to wear and abrasion, valve in the process of valve opening and the sealing surface between the disc and _ the relative sliding, so the sealing surface of wear and abrasion is smaller, so improve the service life of the sealing pair valve in the whole closed process disc stroke small, its height relative to the alarm valve smaller. The disadvantage of the cut-off valve is that the headstock torque is larger and difficult to realize fast and close, because the valve body flow is relatively tortuous, fluid flow resistance, resulting in the fluid power in the pipeline loss.