Globe valve application

by:AIRWOLF     2020-05-24
Cut-off valve is closed ( The valve disc) Along the centerline of the valve gate valve. It mainly in the line cut off. The use of cut-off valve is very common, but since the opening and closing torque is bigger, body is longer, nominal size is usually restricted to DN250. In addition, nominal size of the cut-off valve is related to pressure of work. Globe valve is the most obvious advantages as follows: | 1. In the process of opening and closing, due to the friction between the valve disc and valve sealing surface is smaller than gate valves door, so wear and tear. 2. Open the high than gate valves. 3. Typically on the valve body and valve disc only a sealing surface, thus making craft is good, easy to maintenance. However, the cut-off valve fault is also nots allow to ignore. The downside is mainly caused by internal body cavity of shape. In the body cavity, medium flows upward from the straight line direction into, thus cause the pressure loss, especially in hydraulic equipment, particularly the pressure loss. Many different kinds of cut-off valve, general according to the position of the valve stem threads, channel form, the valve disc shape classification. The main can be divided into: 1. Threaded valve lever cut-off valve on the cut-off valve application is relatively common. It the valve stem threads outside of the shell, not direct contact with the working medium, which can make the valve rod is not affected by media, also facilitate lubrication, easy operation, as shown in figure 2 38. 2. Threaded valve lever cut-off valve under the cut-off valve of the valve stem threads in the valve body, direct contact with the media, not only can't lubrication, and vulnerable to the media, as shown in figure 2 39. The cut-off valve, multi-purpose in nominal size is small and medium temperature is not high. 3. Straight-through cut-off valve medium import two channels in the same direction, in 180 & deg; As shown in figure 2 38 and figure 2 39. This form of cut-off valve the flow state of damage is relatively small, therefore, the loss of pressure across the valve also corresponding reduced. 4. Horn type globe valve type globe valve inlet channel is not in the same direction in 90 & deg; - real Angle, as shown in figure 2 40. This form of cut-off valve made by valve door change flow direction of medium, so will produce a certain pressure drop. Angle type globe valve is one of the biggest advantages is to install the valve door in the corner of the pipeline system, such already save 90 & deg; Elbow, and convenient for operation. This type of valve door in chemical fertilizer plant of synthetic ammonia production system and cooling system. 5. Tee cut-off valve globe valve with three channels, often used as a medium flow direction changes and distribution medium, as shown in figure 2 41. 6. Once-through once-through cut-off valve globe valve stem and valve channel into a point of view, the valve seat cover and inlet channel Angle; The valve body can be made into integral, also can be made into separate type, as shown in figure 2 42. Separate type globe valve valve body with two valve body to clamp valve seat in the middle, convenient for manufacture and convenient for maintenance. Such as valve make almost not change flow direction, fluid cut-off valve for flow resistance is small; Its installation points straight through close to, but should pay special attention to after the pipe installation should be easy to operation. 7. Plunger type globe valve plunger globe valve is normal deformation of the cut-off valve. In the plunger cut-off valve, the valve flap and valve seat is designed according to the principle of the plunger; Pillars plug valve, the valve design complete ring, valve seat design on plunger valve and set of cooperate to achieve sealing ring. The valve door manufacture simple, lantern ring can be made from graphite and ptfe; Good sealing, high and low temperature medium can be used. This valve is mainly used as opening and closing, but the design into a special form of plunger and lantern ring can also be used for flow control. Plunger valve institutional form - as shown in figure 2 23. 8. Needle by needle valve globe valve is as accurate flow control, usually limited to a small, usually the size of the valve seat hole is smaller than nominal size, as shown in figure 2 44.
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