High performance butterflyvalve usuall adopts single eccentric ordouble eccentric structure.Thefirst eccentricity is that shaftdeviates fromcenterine of sealing surface.The second eccentricity is that shalt deviates from centreline of the pipe.Eccentricityaims to reduce the friction betweenthe seal ring and seat after the valve opens to 20°.

Sottseat which adopts TFE,PTFE and RTFE,also has good sealing when the fire occurs,because fireproof structure suits for thefiretest accordingto APl607.

Metal Sealing structure has the entitative fireproof ability,it can assure the zero leakage of bidirection.Seat can be replaced when the shaft and thedisc aren'dismantled.There's nolow friction coefficent bush bearing at up and bottom shafts,so the friction is reduced when the valve is opening andclosing.

Double ecentric structure decreases the damage of secondary sealing when the valve is opening or closing frequently.The interface of the valve and the driving mechanism is suitable for 1$05211,and the quality of product is controlled seriously according to IS05211.

1.The disc is under closing,media enters from the upstream of seat,as media's action of force,seal ring clings to seal surface because of seal ring'sresilience and deformation effect to assure the secondary has a good sealing.

2.The disc is under closing,media enters from the downstream of seat,as pressure plate extrudes up and down,seal ring covers the media's forceaction,and clings to the seal surface to assure the secondary has a good sealing.