1. globe valve) is a plug-shaped disc with a flat or conical sealing surface, and the disc moves linearly along the center line of the fluid. The movement forms of the valve stem are lifting rod type (the valve stem moves up and down, and the handwheel does not move up and down) and lifting rotary rod type (the handwheel rotates up and down with the valve stem, and the nut is installed on the valve body).
2. The globe valve has the following advantages: simple structure and convenient manufacture and maintenance. Short working stroke and short opening and closing time. Good sealing performance, small friction between sealing surfaces and long service life.
3. The disadvantages of the globe valve are as follows: large fluid resistance and large force required for opening and closing. Not suitable for media with particles, high viscosity and easy coking. Poor regulation performance.
4. The main features of the ball valve are compact structure and easy operation and maintenance. Suitable for general working media such as water, solvent, acid, natural gas, etc., and also suitable for media with harsh working conditions such as oxygen, hydrogen peroxide, methane and ethylene. Ball valve body can be integrated or combined.
5. The ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. Ball valve is a new type of valve widely used in recent years. It has the following advantages:
The fluid resistance is small, and its resistance coefficient is equal to that of the same length of pipe. Simple structure, small volume and light weight. Tight and reliable, at present, the sealing surface material of ball valve is widely used in plastic, which has good sealing performance and is widely used in vacuum system. Simple operation, fast opening and closing, only 90 degrees rotation from full opening to full closing, convenient for remote control. Convenient maintenance, simple ball valve structure, movable sealing ring and convenient disassembly and replacement.
6. When fully opened or closed, the sealing surfaces of the ball and the valve seat are isolated from the medium, and when the medium passes through, it will not cause corrosion of the valve sealing surface. ? Its application range is very wide, from small diameter to several millimeters to several meters, from high vacuum to high pressure. Ball valves have been widely used in petroleum, chemical industry, power generation, paper making, atomic energy, aviation, rockets and other departments, as well as people's daily lives.
Extended data:
Globe valves are only suitable for full opening and full closing, and adjustment and throttling are not allowed. Globe valve is a kind of forced sealing valve, so when the valve is closed, pressure must be exerted on the disc to force the sealing surface not to leak. When the medium enters the valve 6 from below the disc, the resistance to be overcome by the operating force is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the diameter of the valve stem should be larger, otherwise the valve stem will bend.
The working principle of ball valve is to make the valve unblocked or blocked by rotating the valve. Ball valve switch is light in weight, small in volume, can be made into large caliber, reliable in sealing, simple in structure, convenient in maintenance, and the sealing surface and spherical surface are often closed, so it is not easy to be eroded by media, and is widely used in various industries. Ball valve and plug valve belong to the same type of valve, only its closing part is a sphere, and the sphere rotates around the center line of the valve body to realize opening and closing.
References:
Stop valve-Baidu encyclopedia
Ball valve-Baidu encyclopedia