Classification and characteristics of pneumatic pneumatic ball valves Pneumatic pneumatic ball valves are a set of devices equipped with pneumatic actuators, solenoid valves, limit switches, air supply triplets and other accessories. Only need the pneumatic actuator to rotate 90 degrees with the air source and a small rotating torque to close tightly. The completely equal inner cavity of the valve body provides a straight flow passage with little resistance for the medium. It is generally believed that pneumatic ball valves are most suitable for direct opening and closing, but recent development has designed pneumatic ball valves to be used for throttling and flow control. It is convenient for pneumatic and pneumatic ball valves to control the opening and closing of valves in a unified way.

COMPREHENSIVE STRESS AND COMPRESSIVE STRENGTH OF COMPENSATOR
It can be seen from the calculation method and evaluation specification of the plane stability and circumferential stability of the compensator given in the specification that both reflect the strength problem. When the allowable life of the compensator design is low, not only the meridian comprehensive stress is high, but also the circumferential stress is relatively high, which makes the compensator part enter plastic deformation quickly, leading to the instability of the compensator.
As for the internal pressure compensator, the displacement stress forms a plastic hinge at the crest and trough of the compensator, and together with the pressure stress, the compensator quickly produces plane instability. This is the basic reason why the plane instability pressure of low fatigue life compensator is far lower than that of high fatigue life compensator under displacement condition. For example, in the pre displacement state, that is, when the displacement of the compensator is 1/2 of the allowable value, a compensator with an allowable fatigue life of 200 times has had plane instability before reaching its allowable design pressure; The compensator with allowable fatigue life of 1000 times is in a plane stable state when it reaches the design pressure, and in a critical unstable state when it reaches 1.5 times the design pressure; When the compensator with the allowable fatigue life of 2000 times reaches 1.5 times of the design pressure, the compensator is still in a plane stable state.
From the longitudinal section of the external pressure compensator, it is equivalent to an arch beam under pressure. When the compensator works, it is in a tensile state, which is equivalent to that the arch beam reduces the arch height, and its ability to resist instability naturally decreases. When the single wave displacement of the compensator is too large, the ripples are straight and partially inclined, which makes the diameter of the crest of the compensator tend to decrease, but the diameter of the ring of the crest is certain. In order to coordinate the deformation, the crest will collapse and the circumferential instability of the compensator will occur. In the corresponding specifications at home and abroad, the influence of displacement on the circumferential stability of external pressure of the compensator has not been touched, which needs further discussion.
To sum up, although up to now, no damage caused by fatigue has been found in the application process of the heat pipe network, the low design fatigue life of the compensator will lead to disastrous results.