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Gate valve a variety of different structures and performance comparison
Gate valve is widely used in the pipeline a valve, the main play and cut off the media role. Does not apply to regulate the flow of media, but according to the height of the stem to determine the size of the flow rate (such as fire with a seat sealing valve with opening and closing scale). Gate valve compared to other valves, the pressure, temperature, diameter and other requirements of the scope of the wider. Gate valve according to the different internal structure can be divided into: wedge single gate type, elastic gate type, double gate type, parallel gate type. According to the different stem holder can be divided into: Ming rod valve and dark rod gate valve. Gate valve main performance advantages are: 1. Valve fluid resistance is small, because the valve body is straight through the type, the flow does not change the direction of the media, so compare other valve flow resistance to be small. 2. Sealing performance is better than the cut-off valve, opening and closing than the cut-off valve labor-saving. 3 wide range of applications, in addition to steam, oil and other media, but also for containing granular solids and viscous media, but also for the vent valve and low vacuum system to use the valve. 4. Gate valve is a dual flow valve, not subject to the restrictions on the flow of media, it is suitable for medium may change the flow direction of the pipeline, but also easy to install. Gate valve main performance shortcomings are: 1. Shape design size is high, a long time off. The valve plate needs to be lifted to the upper part of the valve cavity when it is opened, and the valve plate needs to all fall into the valve seat when it is closed. Therefore, the valve plate has a large opening and closing stroke and a long time. 2. As the gate valve plate and valve seat sealing surface in the process of opening and closing there is friction, so easy to scratch the sealing surface, the sealing performance and service life are affected, and not easy to repair. Several different structure of the gate valve performance comparison: (1) wedge single gate valve a. Structure of the elastic gate valve is simple b. At higher temperatures, the sealing performance is not as good as the elastic gate valve or double gate valve. c. Suitable for high temperature coking medium. (2) Flexible gate valve a. It is a special form of wedge single gate valve. Compared with the wedge gate valve, at high temperature, the sealing performance is good, the gate is not easy to get stuck after heating; b. For steam, high temperature oil and oil and gas media, and applies to frequent switching parts. c. Does not apply to caking media. (3) Double gate valve a. The sealing performance is better than the wedge gate valve. When the angle of the sealing surface and the valve seat are not very accurate, it still has better sealing performance. b. After the sealing surface of the gate is worn, the metal pad at the bottom of the spherical top center can be used after replacing. Generally, there is no need to build welding and grinding sealing surface, which is the advantage that single gate and elastic gate do not have. c. Apply to steam, high temperature oil and hydrocarbon media, and apply to frequent switching parts. d. does not apply to easy caking medium. (4) Parallel Gate Valve a. The sealing performance is worse than other forms of gate valve. b. Suitable for media with lower temperature and pressure. c. Gate and seat sealing surface machining and maintenance than other forms of gate valve simple. Ming rod valve and the difference between the dark rod gate valve: gate valve is up and down through the stem of the drive gate opening and closing, Ming rod gate drive screw thread in the top of the stem bracket, so you can determine the gate opening and closing of the valve stem Position, while the drive thread is also easy to maintain daily lubrication, while fluid erosion, the disadvantage is the installation of larger space requirements. Dark bar gate valve drive thread in the body, saving the stem bracket space, so the entire valve height decreases. On the need to clearly open and close the position, the valve cover can be installed above the opening and closing scale, suitable for the bottom of the gutter (such as underground dark bar gate valve), ditch and other small space, or dust content of the place. Gate valve can also be based on different materials, different pressures, different seals, different connections, divided into different gate valve type.