Several common connections of vacuum valves

Several common connections of vacuum valves

1. Flange connection    

This is the most common form of connection used in valves.According to the shape of the surface can be divided into the following types;

1) smooth;For valves with low pressure.Easy to process

2) concave-convex type;High working pressure, medium hard washer can be used

3) tenon groove type: it can be used as a gasket with large plastic deformation. It is widely used in corrosive media with good sealing effect.

4) trapezoidal groove type: use oval metal ring as gasket for valves with working pressure ≥ 64kg/cm2 or high temperature valves.

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

6) o-ring type, this is a relatively new form of flange connection, it is with the emergence of a variety of rubber o-ring, and developed, it is more reliable in sealing than the general plain gasket.

2. Threaded connection

This is a simple connection and is often used for small valves.There are two situations:

1) direct sealing: the internal and external threads play a direct sealing role.In order to ensure that the joint does not leak, often with lead oil, lint and teflon raw material belt filling;Among them, ptfe raw material belt, widely used;This material has good corrosion resistance, excellent sealing effect, easy to use and preserve, when disassembled, it can be completely removed, because it is a layer of non-viscous film, much better than lead oil, hemp.

2) indirect seal: the force of thread tightening is transferred to the gasket between the two planes, so that the gasket can act asa seal.

3. Card socket connection

Sleeve connection, developed in China in recent years, its connection and sealing principle is that when the nut is tightened, the sleeve is under pressure, making the blade bite into the outer wall of the pipe, and the outer cone of sleeve is closely connected with the inside cone of the joint under pressure, thus it can reliably prevent leakage.

The advantages of this form of connection are:

1) small size, light weight, simple structure, easy to disassemble and assemble:

2) strong relay, wide range of use, able to withstand high pressure (1000 kg/cm2), high temperature (650℃) and impact vibration;

3) can choose a variety of materials, suitable for corrosion;

4) low machining accuracy requirements;

5) easy to install at height.

At present, the form of bayonet connection has been used in some small-caliber valves in China.

4. Clamp connection

This is a quick connection method that requires only two bolts and is suitable for frequently removed low pressure valves.

5. Internal self-tightening connection

Above all kinds of connection forms, are the use of external forces to offset the pressure of the medium, the realization of sealing.The following describes the use of medium pressure for self - tightening connection.Its sealing ring installed in the inner cone, with the media facing the side into a certain Angle, medium pressure to the inner cone, and transfer to the sealing ring, in a certain Angle of the cone, produce two components, one is parallel to the center line of the valve body outward, another pressure to the inner wall of the valve body.The latter component is the self - tightening force.The greater the medium pressure, the greater the self-tightening force.Therefore, this type of connection is suitable for high-pressure valves.It is more than the flange connection, to save a lot of materials and manpower, but also need a certain amount of early warning force, so that in the door pressure is not high, the use of reliable.

Use from close seal the valve that principle makes, it is decorous valve commonly