In this paper, what is the national standard globe valve and its characteristics are analyzed in detail. If you think the answer is helpful to you, please give a compliment to the American Witton VTON valve.
Globe valves imported from China are also called globe valves, which adopt national standards. Its opening and closing part is a plug-shaped disk, which seals the valve with a plane or a sea cone, and the disk moves linearly along the center line of the valve seat to realize the opening and closing of the valve. The movement form of valve stem (commonly known as hidden rod) and lifting rotary rod can also be used to control the flow of various types of fluids such as air, water, steam, corrosive medium, mud, oil, liquid metal and radioactive medium.
The stem axis of globe valve is perpendicular to the sealing surface of valve seat. The opening or closing stroke of the valve stem is relatively short.
Once the disc of the globe valve is in the open state, its valve seat and the sealing surface of the disc are no longer in contact, so its sealing surface is less mechanically worn. Because the valve seat and disc of the globe valve are mostly easy to maintain, it is not necessary to remove the whole valve from the pipeline when replacing the seal, which is very suitable for the occasion where the valve and the pipeline are welded together. The above characteristics make the cut-off valve very suitable for cutting off or regulating media and throttling.
When the medium passes through this valve, the flow direction changes. Therefore, the flow resistance of stop valve is higher than other valves.
According to the characteristics of cut-off valve, the characteristics, advantages and disadvantages of cut-off valve (taking Witton VTON cut-off valve as an example) are summarized.
Advantages:
1, in the process of opening and closing, because the friction between the disc and the sealing surface of the valve body is smaller than that of the gate valve, it is wear-resistant.
2. The opening height is generally only 1/4 of the valve seat channel, so it is much smaller than the gate valve;
3. Usually there is only one sealing surface on the valve body and disc, so the manufacturing process is better and the maintenance is convenient.
Because its filler is generally a mixture of asbestos and graphite, it is resistant to high temperature. Generally speaking, stop valves are used for steam valves.
5. Double seal design (bellows+packing) If the bellows fails, the valve stem packing will also be avoided;
6, no leakage outside, and in line with international sealing standards;
7. No fluid loss, reducing energy loss and improving the safety of factory equipment;
8. Long service life, less maintenance times and lower operating cost;
9. Durable bellows seal design ensures zero leakage of the valve stem and provides maintenance-free conditions.
10 bellows seal globe valve adopts the design of bellows seal, which completely eliminates the shortcomings of quick aging and easy leakage of ordinary valve stem packing, not only improves energy efficiency, increases the safety of production equipment, reduces maintenance cost and frequent maintenance, but also provides a clean and safe working environment. For example, American Weidun VTON imported bellows globe valve is a widely used globe valve, which is used by many users in steam pipelines.
Disadvantages:
① Due to the change of the flow direction of the medium through the valve, the minimum flow resistance of the cut-off valve is also higher than that of most other types of valves;
① Due to the long stroke, the opening speed is slower than that of the ball valve.
② The fluid resistance is large, and the force required for opening and closing is large.
③ It is not suitable for media with particles, high viscosity and easy coking.
④ Poor regulation performance.