The pneumatic ball valve with fixed shaft is called fixed pneumatic ball valve. Fixed pneumatic ball valve is mainly used for high pressure and large diameter. According to the installation of the valve seat sealing ring, the fixed pneumatic ball valve can have two structures: the valve seat sealed before the ball, and the valve seat sealed after the ball.

Features of corrugated pneumatic butterfly valve:
1. Maximum allowable shrinkage per wave recommended: full height △ α= ± 24mm half height △ α= ±12mm。
2. Ash baffle: it can not be used for air duct or pipe with little dust, and it should be used for flue with much dust.
3. In order to reduce the number of corrugated sections of bellows, 50% cold drawing shall be considered.
4. The standard half height corrugated pneumatic butterfly valve is applicable to places with a sectional area of less than 4.6 square meters and the overall dimensions of the flue and air duct where one side is less than 1.5 m but more than 0.6 mm. The standard full height corrugated pneumatic butterfly valve is applicable to all flue ducts.