Gate Valve (Vag-eko) Gate valve refers to the closing part (gate) along the channel axis of the vertical movement of the valve, in the pipeline mainly as a cut-off medium used, that is, full open or closed use. Generally, the gate valve can not be used as a regulating flow. It can be applied at low temperature pressure and can be applied to high temperature and pressure, and can be based on different material of valve.
However, gate valves are generally not used for conveying mud and other media pipelines.
Advantages: The ① fluid resistance is small, the torque required for ② and closing is smaller; ③ can be used in the media to the two-direction of the Loop network management, that is, the flow of the media is unrestricted; when the ④ is fully open, the seal face is smaller than the cut-off valve by the working medium, the ⑤ body structure is relatively simple, the manufacturing process is good, and the ⑥ structure length is
Disadvantages: ① size and opening height, the required installation space is also larger; ② in the opening and closing process, the seal of the relative friction, the friction is larger, even in high temperature easily cause abrasions; ③ General gate Valve has two sealing surface, to the processing, grinding and maintenance increased some difficulties; ④ opening and closing time is long.
Butterfly valve (VAG-INTEREX;VAG-EKN)
Butterfly valve is a kind of valve that opens, closes and regulates the fluid passage by rotating the disc-type headstock around 90°. Advantages: ① structure is simple, small size, light weight, supplies province, especially for large-diameter valves; ② open and close quickly, the flow resistance coefficient is small; ③ can be used for media with suspended solids, and can be used for powdery and granular media depending on the strength of the sealing surface.
It can be applied to the two-way on-off and adjusting of the ventilation and dedusting pipeline, and is widely used in the gas pipelines and waterways of metallurgy, light industry, electric power, petrochemical system. Disadvantages: ① flow adjustment range is not large, when the opening up to 30%, the flow will be more than 95%. ② due to the butterfly valve structure and sealing material limitations, not suitable for high-temperature, high-pressure piping system. General operating temperature below 300 ℃, PN40 (6~40) below.
③ sealing performance relative to the ball valve, cut-off valve is poor, so the sealing requirements are not very high place.
Ball valve is from the plug valve evolved, its headstock is a ball, the use of the ball around the stem axis rotation of 90 ° to achieve the opening and closing purposes.
The ball valve is mainly used for cutting, distributing and changing the flow direction of the medium, and the ball valve designed as V-shaped opening has good flow regulation function. Advantages: ① has the lowest flow resistance (actually 0); ② is not stuck when working (in the absence of lubricant) Therefore, it can be applied reliably in corrosive medium and low boiling liquid, and the ③ can be fully sealed in the range of pressure and temperature, the ④ can realize the rapid opening and closing, and the open and close time of some structures is only 0.05~0.1s, To ensure that it can be used in the automation system of the test bed. Fast opening and closing valve, the operation without impact. The ⑤ spherical closed parts can be positioned automatically at the boundary position, and the ⑥ working medium is sealed reliably on both sides; ⑦ the sealing surface of the ball and the seat is separated from the medium in full open and closed, so the medium with high speed through the valve will not cause the erosion of the sealing surface; ⑧ Compact and lightweight It is considered that it is the most reasonable valve structure for cryogenic medium system, the ⑨ valve body symmetry, especially the welded valve body structure, can withstand the stress from the piping well, and the ⑩ close part can withstand the high pressure difference when it closes.
⑾ fully welded valve body ball valve, can be buried directly in the ground, so that the valve is not eroded, the maximum service life of up to 30 years, oil, natural gas pipeline is the most ideal valve. Disadvantage: ① because the ball valve is the most important valve seat sealing material is PTFE, it is inert to almost all chemical substances, and has a small friction coefficient, stable performance, not easy to aging, wide range of temperature application and excellent sealing performance of the comprehensive characteristics. However, the physical properties of PTFE, including higher coefficient of expansion, sensitivity to cold flow and poor heat conductivity, require that the design of the seat seals be carried out around these characteristics. Therefore, when the sealing material hardens, the reliability of the seal is damaged. Moreover, the temperature resistance of PTFE is lower and can only be used in less than 180 ℃. More than this temperature, the sealing material will be aging. And considering the long-term use of the case, generally will only be used in 120 ℃.
② its adjustment performance relative to the cut-off valve to some, especially the pneumatic valve (or electric valve).
Globe Valve (Vag-mono) is the valve that closes the piece (disc) to move along the seat centerline. According to this type of movement of the disc, the change of valve seat pass is proportional to the disc stroke. As the valve stem opening or closing of the valve is relatively short, and has a very reliable cutting function, but also because of the valve seat through the mouth of the changes and the disc's journey into a positive proportional relationship, very suitable for the flow of regulation.
Therefore, this type of valve is ideal for cutting off or regulating and throttling. Advantages: ① In the process of opening and closing, because the friction between the valve and body sealing surface is smaller than the gate valve, so wear-resistant. ② opening height is generally only 1/4 of the seat channel, so it is much smaller than the gate valve; ③ usually has only one sealing surface on the valve body and disc, so the manufacturing process is better and easy to repair. ④ because its filler is generally asbestos and graphite mixture, so the temperature-resistant grade is higher.
General steam valves are used as globe valves.
Disadvantage: ① as the media through the flow direction of the valve has changed, so the minimum flow resistance of the cut-off valve is higher than most other types of valves; ② because of the long stroke, the opening speed is slower than the ball valve.