The opening and closing parts of the stop valve are plug-shaped disc, the sealing surface is flat or conical, and the disc moves in a straight line along the center line of the fluid. The movement form of the valve rod includes the lifting rod type (the valve rod is lifted and the handwheel is not lifted) and the lifting rotating rod type (the handwheel is rotated and lifted together with the valve rod, and the nut is set on the valve body). The function of stop valve is only applicable to full open and full close, and it is not allowed to regulate and throttle. This is mainly determined by the characteristics of the stop valve, as follows:
The most obvious advantages are:
In the process of opening and closing, the friction force between the disc and the sealing surface of the valve body is smaller than that of the gate valve, so it is wearable.
Generally, the opening height is only 1 / 4 of the valve seat channel diameter, so it is much smaller than the gate valve.
Generally, there is only one sealing surface on the valve body and disc, so the manufacturing process is relatively good and easy to maintain.
The function of the stop valve is mainly to cut off the medium in the pipeline. Compared with gate valve, it has better regulating performance, small opening height, short closing time, convenient manufacturing and maintenance, and its sealing surface is not easy to wear and scratch, with good sealing performance and long service life; the valve body structure design of stop valve is zigzag, so it has large flow resistance and large energy consumption; it is suitable for medium such as steam and oil products, and it is not suitable for medium with large viscosity, particles, coking and precipitation. The medium. Medium and high pressure stop valves and large diameter stop valves can be of balanced structure. Throttle valve, the extension product of stop valve, controls the pressure and flow of medium by changing the cross section of flow passage. Except that the opening and closing parts are of streamline cone shape, most of them are the same as the stop valve.
When the globe valve is opened, when the opening height of the disc is 25%-30% of the nominal diameter, the flow rate reaches the maximum, indicating that the valve has reached the full open position. Therefore, the full open position of the stop valve shall be determined by the stroke of the disc.
Post time: Oct-16-2019