A vacuum valve is a valve whose operating pressure is lower than the standard atmospheric pressure.
The vacuum valve is the valve whose working pressure is lower than the standard atmospheric pressure applied to the vacuum system. The vacuum valve has the advantages of simple structure, small volume, light weight, material consumption, installation of small size, and torque is small, simple, rapid, and also has good flow characteristics of regulation and sealed off, vacuum valves in the large size, low pressure has widely used in the.
Common types of vacuum valve vacuum valve, vacuum valve, high vacuum high vacuum butterfly valve, diaphragm valve, electro vacuum charging valve, electromagnetic high vacuum valve trim, high vacuum flapper valve, high vacuum flapper valve, ultra high vacuum flapper valve, ultra high vacuum gate valve etc..
Vacuum valves are manual, pneumatic, electric and electromagnetic action of four types, respectively by hand, compressed air, power supply and electromagnetic force as the driving force, the actuator drives the valve plate (spool valve, the valve opening and closing).
Common connection forms:
Flexible flange connection
This is the most widely used form of connection in valves. According to the shape of the joint surface, it can be divided into the following several kinds:
1. smooth: for the pressure is not high valve. Processing is more convenient.
2. concave convex type: higher working pressure, the use of medium hard washers.
3. mortise and groove type: plastic deformation can be larger washers, corrosive medium in the use of more extensive, the sealing effect is better.
4. the trapezoidal groove type: Oval metallic ring gasket used in working pressure greater than 64 kg / cm2 valves, or high temperature valve.
5. Lens type: washer is lens shape, made of metal. For 100 kg / cm2 high-pressure valve working pressure is greater than or equal to, or high temperature valve.
6. O ring type: This is a relatively new form of flange connection, it is developed with the appearance of various rubber O ring, it is more reliable than the ordinary flat washer in the sealing effect.
This is a simple connection method, often used in small valves. There are two kinds of situations:
1. Direct seal: internal and external thread directly sealing effect. In order to ensure that connections do not leak, often lead oil, hemp and PTFE filled with raw materials; including Teflon tape, become more widely used; good corrosion resistance of this material, the sealing effect is excellent, easy to use and preservation, demolition, you can be completely removed, because it is a layer of film inviscid, than lead oil, hemp is much better.
2. Indirect seal: screw tightening force, transfer to the gasket between the two planes, so that gasket sealing effect.
Quick release flange connection
Clamp the sealing O ring and valve flange to achieve better sealing