Pneumatic ball valve is evolved from plug valve. It has the same 90 degree rotation action, but the difference is that the pneumatic ball valve is a sphere with a circular through hole or channel through its axis. The proportion of the sphere and the passage opening should be the same, that is, when the sphere rotates 90 degrees, the inlet and outlet should all be spherical, so as to cut off the flow. The pneumatic ball valve can be closed tightly with only 90 degree rotation and very small rotating torque. The completely equal inner cavity of the valve body provides a straight flow passage with little resistance for the medium.

Understand the important accessories of tetrafluoro compensator and the application of welded contraction joint
Outer cover: it is used to provide certain maintenance for the surface of corrugated pipe of corrugated contraction joint, so as to prevent it from contact with foreign matters or mechanical damage. Sometimes called maintenance sleeve.
Limitrod: a part set on the shrink joint assembly, usually made of a rod or bar, which is mainly used to limit the range of movement (axial, transverse, angular) of the bellows under normal working conditions. When the main fixed support is damaged, this part can avoid excessive stretching and tightening of the bellows, At the same time, it can also control all internal pressure loads and dynamic loads caused by support destruction. The important parts are the important guarantee to ensure the normal operation of the corrugated contraction joint. These parts should be properly selected according to different application conditions.
Inner liner: the cylinder used to reduce the contact between the inner wall of the bellows of the contraction joint and the moving medium passing through it, also called the inner sleeve or the guide cylinder. The information of the inner liner can be the same as or different from that of the bellows.
Welded bellows is a new type of element that has emerged at home and abroad in recent years. It can generally be used as sensing element, sealing element, isolation medium, pipeline connection and temperature compensator. In addition to the advantages of pressure resistance, temperature resistance, corrosion resistance and good sealing, it has two outstanding advantages over the traditional formed bellows: large deformation and long service life. Applying these two characteristics of welded bellows to the thermoacoustic machinery, it is believed that it can deal with many problems disturbing thermoacoustic experts for many years. After decades of research, thermoacoustic machinery has made great progress, especially in recent years, because of its short life and pollution-free outstanding characteristics, thermoacoustic machinery has attracted more and more attention. The tetrafluoro compensator has undergone tremendous changes from the original Sondhauss tube oscillation to today's standing wave and traveling wave initiators and refrigerators, from the original Rayleigh principle to today's linear thermoacoustic theory, and nonlinear thermoacoustics, which makes us fully believe that a period of widespread application of thermoacoustics is coming. However, there are still many problems to be solved in thermoacoustic machinery, such as how to shorten the resonance tube and reduce the system volume, so that it can enter the stage of applicability faster; How to suppress the thermoacoustic direct current in the traveling wave initiator and improve the efficiency of thermoacoustic conversion, etc.
Corrugated pipe is a flexible flexible element, and Teflon compensator can be roughly divided into two types from the appearance: one is welded corrugated pipe with large expansion, and the other is formed corrugated pipe with small expansion. They can be used for sealing mechanical installation, or as contraction joints of vacuum pipelines, and are widely used in vacuum, semiconductor, petrochemical, instrument, medical, aviation and military fields. The forming bellows are integrally formed, with less shrinkage and short service life. In thermoacoustic machinery, there is no report on other aspects except for compensation for thermal expansion and cold contraction on the traveling wave initiator loop.