vacuum valve common connection forms

About several common connection forms of vacuum valve, EVP vacuum pump manufacturer will introduce relevant contents for you. If you have any questions, please feel free to contact us!

1. Flange connection

This is the most commonly used connection form in vacuum valves. According to the shape of the joint surface, it can be divided into the following types:

1) Smooth type: for valves with low pressure. The processing is convenient

2) Concave convex type: high working pressure, medium hard washer can be used.

3) Tenon and groove type: the washer with large plastic deformation can be used widely in corrosive medium, and the sealing effect is good.

4) Trapezoidal groove type: use oval metal ring as gasket, used in valve with working pressure ≥ 64kg / cm2, or high temperature valve

5) Lens type: the gasket is lens shaped and made of metal. For high pressure valve with working pressure ≥ 100kg / cm2, or high temperature valve.

6) O-ring type: This is a new type of flange connection. It is developed with the appearance of various rubber O-rings. It is more reliable than ordinary flat gaskets in sealing effect.

2. Threaded connection

This is a simple connection method, which is often used for small valves. There are two situations

1) Direct sealing: internal and external threads play a direct role in sealing. In order to ensure that the joint does not leak, it is often filled with lead oil, thread hemp and polytetrafluoroethylene raw material belt; among them, polytetrafluoroethylene raw material belt is widely used; this material has good corrosion resistance, excellent sealing effect, and is convenient for use and preservation. When disassembling, it can be completely removed because it is a layer of non viscous film, which is much better than lead oil and thread hemp.

2) Indirect sealing: the force of thread tightening is transmitted to the gasket between two planes, so that the gasket plays a sealing role.

3. Ferrule connection

Ferrule connection has only developed in China in recent years. Its connection and sealing principle is that when the nut is tightened, the ferrule is under pressure, which makes its edge bite into the outer wall of the pipe, and the outer cone surface of the ferrule is closed with the inner cone of the joint under pressure, so that the leakage can be prevented reliably.

The advantages of this form of connection are:

1) Small size, light weight, simple structure and easy disassembly;

2) It can withstand high pressure (1000 kg / cm2), high temperature (650 ℃) and shock vibration;

3) A variety of materials can be selected for corrosion protection;

4) The machining accuracy is not high;

5) Easy to install at high altitude.

At present, ferrule connection has been used in some small caliber valve products in China.

4. Clamp connection

This is a quick connection method, it only needs two bolts, it is suitable for the low pressure valve which is often disassembled.

5. Internal self tightening connection

The above various connection forms, are the use of external forces to offset the pressure of the medium, to achieve sealing. The following describes the use of medium pressure for self tightening connection. Its sealing ring is installed at the inner cone and forms an angle with the opposite side of the medium. The medium pressure is transmitted to the inner cone and then to the sealing ring. On the conical surface with a certain angle, two components are generated, one is parallel to the center line of the valve body, and the other is pressed to the inner wall of the valve body. The latter component is the self tightening force. The larger the medium pressure, the greater the self tightening force. Therefore, this type of connection is suitable for high pressure valves. Compared with flange connection, it can save a lot of materials and manpower, but it also needs a certain pre tightening force, so that it can be used reliably when the pressure in the valve is not high. The valve made of self tightening sealing principle is generally high pressure valve.

There are many forms of vacuum valve connection, for example, some small valves which do not need to be removed are welded with the pipe; some non-metallic valves are connected by socket and socket connection, etc. Vacuum valve users should be treated according to the specific conditions.

 

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