There are many types of vacuum valves ,which play an important rolein the vacuum system . They are usually classified according to their functions, structure types, driving methods, materials and uses. But what are the common connection forms of vacuum valves?
1. Flange connection.
This is a commonly used connection form in valves.
2. Threaded connection.
This is a simple connection method, often used for small valves. There are two situations :
1) Direct sealing: internal and external threads are directly sealed. In order to ensure that the joint does not leak, it is often filled with lead oil, silk hemp, and PTFE material tape; among them, PTFE material tape is widely used; this material has good corrosion resistance, excellent sealing effect, and convenient use and storage , It can be completely removed when disassembling, because it is non-sticky, it is much better than lead oil and thread hemp.
2) Indirect sealing: The screw tightening force is transmitted to the gasket between the two planes, making the gasket play a sealing role.
3. Clamp connection.
The ferrule connection has only been developed in our country in recent years. Its connection and sealing principle is that when the nut is tightened, the ferrule is pressed to make its edge bite on the outer wall of the pipe, and the outer cone of the ferrule is in close contact with the inner cone of the connector under pressure, thereby reliably preventing leakage.
The advantages of this connection form are :
1) Small size, light weight, simple structure, easy to disassemble and assemble;
2) Firm connection, wide application range, high pressure resistance (1000kg/cm2), high temperature resistance (650℃), shock and vibration resistance;
3) A variety of materials can be selected, suitable for anti-corrosion;
4) The processing accuracy is not high;
5) Easy to install at high altitude.
At present, some small-diameter valve products in our country have been connected by ferrules.
4. Clamp connection.
This is a quick connection method that only requires two bolts and is suitable for low-pressure valves that are frequently disassembled.
5. Internal self-tightening connection.
The above connection forms all use external force to offset the medium pressure and achieve sealing.