Features of pneumatic three piece ball valve:
1. Pneumatic control valve Pneumatic three piece ball valve is simple in structure, small in size, light in weight, and low in fluid resistance. Its resistance coefficient is equal to that of pipe sections of the same length.
2. The pneumatic three piece ball valve is easy to maintain, the pneumatic ball valve is simple in structure, the sealing ring is generally movable, and it is easy to remove and replace.
3. Tight and reliable. At present, plastic is widely used as the sealing surface material of the ball valve with good sealing performance, and it has also been widely used in the vacuum system.
4. Convenient operation, fast opening and closing, 90 ° rotation from full opening to full closing, convenient for remote control.
5. It has a wide range of applications, ranging from a few millimeters to several meters in diameter, from high vacuum to high pressure. 6. When the valve is fully opened or closed, the sealing surface of the ball and valve seat is isolated from the medium. When the medium of the self operated regulating valve passes through, it will not cause erosion of the valve sealing surface.

Advantages and correct application of rotary compensator
(1) The compensation amount is large, which can be arranged according to the natural terrain and pipeline strength. The largest group of rotary compensators can compensate 500m pipe section;
(2) . There is no blind plate force generated by medium pressure, and the fixed support can be made very small, especially suitable for large diameter pipes;
(3) The rotary sealing performance is superior, and long-term operation requires no maintenance;
(4) Investment is greatly saved;
(5) Convenient design and calculation;
(6) It can be installed on steam buried pipe and hot water buried pipe, which can greatly save investment and improve operation safety.
The rotary compensator is usually installed in a group of 150~500m devices on the pipeline (it can be determined according to the natural terrain). There are more than ten device modes, which can be determined according to the pipeline direction. After using this type of compensator, the spacing between fixed supports will increase. In order to prevent the deflection of the pipe section, the guide support should be properly increased. In order to reduce the friction resistance of the operation of the pipe section, rolling bearings should be installed on the sliding support.
The rotary compensator can greatly absorb the single wave displacement of the bellows with low fatigue life in application, but at the same time, the comprehensive stress of the bellows has also been greatly improved, which will certainly have a greater impact on the strength and stability of the bellows. The comprehensive stress and compressive strength of bellows are both strength indicators. When the allowable service life of the bellows scheme is low, not only the meridian comprehensive stress is high, but also the circumferential stress is relatively high, which makes the local bellows enter plastic deformation quickly, leading to the instability of the bellows.
As for the internal pressure bellows, the displacement stress forms a plastic hinge at the wave crest and wave trough of the bellows. Combined with the pressure stress, the bellows will soon suffer from plane instability. This is the fundamental reason why the plane instability pressure of bellows with low fatigue life is far lower than that of bellows with high fatigue life under the premise of displacement. For example, in the pre displacement configuration, when the displacement of the bellows is 1/2 of the allowable value, a bellows with a allowable fatigue life of 200 times will suffer from plane instability before reaching its allowable scheme pressure; For the bellows with the allowable fatigue life of 1000 times, when reaching the scheme pressure, the bellows will be in the plane stable state, and when reaching 1.5 times the scheme pressure, the bellows will be in the critical unstable state; When the allowable fatigue life of the bellows is 2000 times and reaches 1.5 times of the scheme pressure, the bellows is still in a plane stable shape.
The main problems of rotary compensator are the stability and falling of bellows. The stability of bellows can be solved through scientific analysis of bellows waveform parameters, fatigue life, accurate installation and stress analysis of piping system. There are two ways to deal with the problem of corruption:
(1) Scientific bellows material selection and compensator structural scheme can block the source of falling.
(2) Strengthen the treatment of accumulated water in the chamber and fundamentally deal with the problem of degeneration.