Opening and closing speed regulation of pneumatic butterfly valve
There are many ways to adjust the opening and closing speed of the pneumatic butterfly valve. First, the quick exhaust valve can make the pneumatic butterfly valve open and close more quickly. On the contrary, if the pipeline is equipped with a quick exhaust valve, the opening and closing speed will slow down. The opening and closing speed of pneumatic butterfly valve can also be adjusted by adjusting the air source pressure. A positioner is added to regulate the flow in the pipeline. Adjusting the flow of the pipeline changes the impact on the pipeline and can also regulate the opening and closing speed of the pneumatic butterfly valve.

The manufacturing methods of non-metallic contraction joints include:
Mechanical bulging, hydroforming, rolling forming, welding forming, and electro deposition forming. Hydroforming can obtain bellows with better comprehensive performance; Rolling forming can be used to manufacture large diameter bellows; The bellows with good elasticity can be formed by welding; Electrodeposition forming can produce corrugated pipes with small diameter and high precision.
The design of non-metallic contraction joint is very complicated, and it needs to calculate and check the following parameters: pressure resistance ability, stress caused by displacement, fatigue life, stiffness and stability.
Stiffness: force required to make bellows produce unit displacement. It is the basis for calculating the elastic thrust of corrugated contraction joints. For bellows with the same diameter and pressure, the stiffness is one of the parameters to weigh the performance of bellows. At present, the consumer manufacturers use the EJMA method to calculate the single wave axial stiffness (fir) of the bellows, from which the axial stiffness (Kx) of the shrink joint is obtained. The stress in non-metallic contraction joints is mainly caused by internal pressure and displacement. The stress caused by displacement is usually greater than the stress caused by internal pressure. It is generally higher than the compliance force of bellows data along the meridian direction (longitudinal direction) of bellows.