Plug valve, a valve that uses a plug body with a through hole as the opening and closing member. The plug body rotates with the valve rod to achieve opening and closing action ,A small plug valve without packing is also known as a “cock”. The plug body of the plug valve is mostly a conical body (also known as a cylinder), which cooperates with the conical hole surface of the valve body to form a sealing pair. Plug valve is the earliest type of valve used, with simple structure, rapid opening and closing, and low fluid resistance.Ordinary plug valves rely on the direct contact between the finished metal plug body and the valve body to seal, resulting in poor sealing performance, high opening and closing force,and easy wear. They are generally only used in low (not higher than 1 MPa) and small diameter (less than 100 mm) applications. In order to expand the application range of plug valves, many new structures have been developed. The oil lubricated plug valve is the most important type. Special lubricating grease is injected from the top of the plug body between the tapered hole of the valve body and the plug body to form an oil film to reduce the opening and closing torque, improve sealing performance and service life. Its working pressure can reach 64 MPa, the maximum working temperature can reach 325 ℃, and the maximum diameter can reach 600 mm. There are various forms of passage for plug valves. The common straight through type is mainly used to cut off fluid. Three-way and four-way plug valves are suitable for fluid reversing plug valves. The opening and closing member of the plug valve is a perforated cylinder that rotates about an axis perpendicular to the channel, thereby achieving the purpose of opening and closing the channel. Plug valves are mainly used to open and close pipelines and equipment media.
The main advantages of plug valves are as follows:
1. Suitable for frequent operation, quick and light opening and closing.
2. Low fluid resistance.
3. Simple structure, relatively small size, light weight, and easy maintenance.
4. Good sealing performance.
5. The flow direction of the medium can be arbitrary, regardless of the installation direction.
6. No vibration, low noise.
7. Plug valves can be divided into four types according to their structure: tight set plug valves, self sealing plug valves, packing plug valves, and oil injection plug valves. According to the channel type, it can be divided into three types: straight through type, three-way type, and four-way type.
Post time: Mar-21-2023