Automatic pressure relief structure: when the pressure in the middle chamber rises abnormally, the medium in the middle chamber can automatically relieve the pressure by pushing the valve seat with its own thrust, thus ensuring the safety of valve lifting.

The opening and closing part of the ventilation butterfly valve is a disc shaped butterfly plate, which rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjustment. The butterfly valve is generally less than 90 ° from full opening to full closing, and the butterfly valve and butterfly stem have no self-locking capacity. In order to position the butterfly plate, a worm gear reducer should be installed on the valve stem. The use of worm gear reducer can not only make the butterfly plate have self-locking ability, make the butterfly plate stop at any position, but also improve the operating performance of the valve. Special industrial butterfly valve is characterized by high temperature resistance, high applicable pressure range, large nominal diameter of valve, carbon steel valve body, and metal ring instead of rubber ring for sealing ring of valve plate. The large high-temperature butterfly valve is welded with steel plate and is mainly used for the flue and gas ducts of high-temperature media.