This corrosion resistant butterfly valve is separated style,enclosed the valve with PTFE liner ring.It can be fit for various corrosive and dangerous medium.Between the liner ring and valve is the back liner which was made of high-elasticity rubber,the liner ring disc adopts the double spherical surface even some laceration emerges due to long-time using.With the ascendant design,it will be safety and no leaking out during long-term use.