Manner null of assembling the sheet ring and the said sheet ring of decentering die butterfly

摘要

PROBLEM TO BE SOLVED: To provide a seat ring to hold a seal function without damage, such as wear, even on a high degree fluid specification condition and provide an increased life and to provide assembly method therefor. ;SOLUTION: In an eccentric type butterfly valve wherein an annular seat ring is located between one end part of a hollow cylindrical body formed of a rigid material and the peripheral edge of a valve element, a seat part 12c in the shape of an angle in cross section to bring the peripheral edge of the valve element into pressure contact with an annular seat ring 12a during closing of a valve is continuously formed along a peripheral direction at an annular seat ring 12a. The position in a peripheral direction of a point 21, at which the whole periphery of the peripheral edge of the valve element 14 makes approximately simultaneous contact with the side of the angle seat part 12c at the annular seat ring 12a during closing of a valve is formed in a developed state from a straight line 21a in the vicinity of a position paralleling a valve spindle insertion part and formed from a cosine curve 21b in a section except the vicinity of a valve spindle insertion parallel part formed from the straight line 21a. Further, a portion between the terminal end 22 of the skirt of the angle seat 12c of an approximate simultaneous contact point 21 with the peripheral edge of the valve element at the straight line and the cosine curve and the edge 12e of the seat ring forms a flat 12f.;COPYRIGHT: (C)1999,JPO