What two kinds of structure can butterfly valves be divided into?

Butterfly valve is divided into two forms, one is double eccentric butterfly valve, two is medium type butterfly valve, the two have the same points and differences. The following is a brief introduction:

Double eccentric butterfly valve: In the valve stem shaft deviates from the center of the disc, also deviates from the center of the body, the effect of double eccentricity enables the disc to be quickly removed from the seat after the valve is opened, which greatly eliminates the unnecessary excessive extrusion and scratching phenomenon of the disc and the seat, reduces the opening resistance, reduces the wear, and improves the life of the seat. However, the sealing effect of the disc through the elastic deformation caused by squeezing the seat, The location of the closure is very demanding.

Medium type butterfly valve: stem shaft, plate center, body is in the same position, simple structure, shortcomings of plate and seat is always in the extrusion, scraping state, wear fast, but because of its sealing material in the use of temperature restrictions