What kind of working conditions need to choose a shut-off valve
The globe valve is one of the more widely used valves. The reason why it is popular is that the friction between the sealing surfaces during the opening and closing process is small, it is relatively durable, the opening height is not large, the manufacturing is easy, and the maintenance is convenient. Low pressure, but also suitable for high pressure. The closing principle of the globe valve is to rely on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat closely fit to prevent the medium from flowing. It can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Therefore, this type of shutoff valve is very suitable for shutting off or regulating and throttling. Because the opening or closing stroke of the valve stem of this type of valve is relatively short, and it has a very reliable shut-off function, and because the change of the valve seat port is in direct proportion to the stroke of the valve disc, it is very suitable for flow adjustment.
The stem axis of the globe valve is perpendicular to the sealing surface of the valve seat. The opening or closing stroke of the valve stem is relatively short, and it has a very reliable cut-off action, making this valve very suitable for the cut-off or adjustment and throttling of the medium.
Once the valve disc of the shut-off valve is in the open condition, there is no longer contact between its valve seat and the sealing surface of the valve disc, and it has a very reliable cut-off action. This kind of valve is very suitable for cutting or adjusting and reducing the medium. Stream usage.
Once the shut-off valve is in the open state, there is no contact between its seat and the sealing surface of the disc, so its sealing surface is less mechanically worn, because most of the shut-off valve seats and discs are easier to repair or replace It is not necessary to remove the entire valve from the pipeline when sealing the components, which is very suitable for the occasion where the valve and the pipeline are welded together. The flow direction of the medium through this type of valve has changed, so the flow resistance of the stop valve is higher than that of other valves.
Commonly used globe valves are as follows:
1. Angle type stop valve: In the angle type stop valve, the fluid only needs to change its direction once, so that the pressure drop through this valve is smaller than that of the conventional structure of the stop valve.
2. Direct-flow stop valve; in direct-flow or Y-shaped stop valve, the flow passage of the valve body is in a diagonal line with the main flow passage, so that the degree of damage to the flow state is smaller than that of the conventional stop valve, so the pressure loss through the valve is also corresponding Is too small.
3. Plunger type globe valve: This type of globe valve is a modification of the conventional globe valve. In this valve, the disc and valve seat are usually designed based on the plunger principle. The valve clack is polished so that the plunger and the valve stem are connected, and the sealing is achieved by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a sleeve ring, and the sealing ring around the plunger is pressed firmly by the load exerted on the bonnet by the bonnet nut. The elastic sealing ring can be replaced and can be made of various materials. The valve is mainly used for "open" or "close", but it is equipped with a special form of plunger or special collar, which can also be used to adjust the flow rate. .