The shut-off valve refers to the valve whose closing part (disc) is along the center line of the valve seat. It mainly cuts off the pipeline.
The use of shut-off valves is very common, but due to the large opening and closing torques and longer mechanisms, the nominal size is usually limited to less than DN250. In addition, the nominal diameter of the globe valve is also related to the working pressure.
The most obvious advantages of the globe valve are as follows:|
1. During the opening and closing process, the friction between the valve clack and the sealing surface of the valve body is smaller than that of the gate valve, so it is worn.
2. The opening height is much smaller than the gate valve.
3. Usually there is only one sealing surface on the valve body and the valve disc, so the manufacturing process is better and easy to maintain.
However, the shortcomings of the globe valve cannot be ignored. Its disadvantages are mainly caused by the shape of the body cavity. In the body cavity, the medium changes from a straight direction to an upward flow, which causes pressure loss, especially in hydraulic devices, this pressure loss is particularly obvious.
There are many types of globe valves, which are generally classified according to the position of the thread on the stem, the form of the passage, and the shape of the disc.
Mainly can be divided into:
1. Upper threaded stem globe valve
2. Lower thread stem globe valve
3. Straight-through globe valve
4. Angle globe valve
5. Three-way globe valve
6. Direct current globe valve
7. Plunger type globe valve
8. Needle globe valve