eak away from the seat rapidly, which reduced the seal pair’s abrasion, friction torque is small, it’s flexible to open.Conical surface can enable the disc to reach sealing by through seat’s inner bore when the valve be open or closed.Conical disc’s turning radius is larger than contact location’s turning radium of seal pair, so the disc will be more tight when the valve be closed tightly more and more to reach self-locking?4, The triple eccentric butterfly valve, which makes use of a metl