Globe valve It is one of the most widely used valves. Due to the small friction force, long service life, low opening height, easy to manufacture and maintenance, the sealing surface is not only suitable for medium and low pressure, but also suitable for high pressure. The closing principle of globe valve depends on the pressure of the valve stem to make the sealing surface of the valve disc and the sealing surface of the valve seat closely combined to prevent the flow of medium. It can be used to control the flow of air, water, steam, various corrosive media, mud, oil, metal liquid and radioactive medium. Therefore, this type of globe valve is very suitable for closing, regulating and throttling. Because the valve stem opening or closing stroke is relatively short, it has very reliable cutting function, and the change of valve seat opening degree is directly proportional to the stroke of valve disc, so it is very suitable for regulating flow.
The sealing surface of the stop valve stem is perpendicular to the axis of the valve seat. The valve stem can be opened or closed relatively reliably by the medium.
Welded stop valve Once the enterprise is in the development and opening economic situation, the valve seat and disc sealing surface design will no longer be in contact, and has a very safe and reliable cut-off action, so this valve is very suitable for China as a medium for cutting off or regulating and throttling.
Once the valve is in the open state, it is no longer in contact between the valve seat and the valve sealing surface, thus causing mechanical wear of the smaller sealing surface. Since most valve seats and valves are easy to be repaired or replaced, it is not necessary to remove the said valve from the pipeline. When the sealing element is used, the occasions where the valve and the pipe are welded together are applicable. When the medium changes the direction of flow through such a valve, the flow resistance, and therefore higher shut-off in other valves.
The commonly used globe valves are analyzed as follows:
1. Angle stop valve; in the angle stop valve, the fluid only needs to change the direction once, so that the pressure drop through the valve is less than that of the conventional structure.
In the direct current or Y-shaped globe valve, the flow path of the valve body is diagonal to the main channel, so the destruction of the fluid state is less than that of the conventional stop valve, so the pressure loss through the valve is also relatively small.
3. Plunger valve: This is the conventional form of the stop valve variant of the stop valve. In valves, the valve and seat are usually based on the plunger principle. The polished valve rod is connected with the plunger, which is sealed by two elastic sealing rings around the plunger. Two elastic rings open through a collar, and the load is applied to seal around the plunger bonnet firmly pressed by the bonnet nut. The elastic ring can be replaced or made of various materials. It is mainly used to "open" or "close" valves. However, a special form of a plunger or special ring can also be used to regulate flow.