When the valve is fully open, a sealing device that prevents the medium from leaking to the stuffing box is called the upper sealing device.
When the gate valve, globe valve and throttle valve are in the closed state, because the medium flow direction of the globe valve and the throttle valve flows upward from under the valve disc, there is no pressure in the body cavity, and the pressure in the body cavity is lower than the working pressure when the gate valve is closed, so the pressure of the medium on the packing is very small. When opened, the packing will bear the working pressure, if there is an upper sealing structure, it can prevent the working medium pressure from acting on the sealing packing, extend the life of the sealing packing, so that the valve will not leak.
Its other function is that when there is leakage at the sealing packing, the valve can be fully opened to seal the upper seal, so that the packing gland or packing gland can be loosened, the packing is increased, and then the filling cover is pressed, so as to ensure that the valve packing is dense and there is no leakage, therefore, for the gate valve, globe valve, throttle valve to provide for the upper sealing device.
The information above from Tianjin Tanggu Water-seal valve Co.,ltd.
Post time: Apr-08-2023