Abstract: A check valve has a valve body with an annular seat surrounding the duct and a flap member pivotally mounted on the valve body so as to pivot about an axis transverse to the duct from an open position to a closed position pressing against the seat. The flap member includes a circular flap plate with a rigid backer plate and a front resilient layer carried on a pivot mounting bracket having a rigid mounting plate generally parallel to the backer plate. The backer plate and the mounting plate each have a central hole therethrough and are connected by an integral body molded from a resilient elastomeric material to form the front resilient layer, a back stopper portion and a connecting neck portion arranged so as to provide resilient flexing movement between the flap plate and the mounting bracket. The mounting bracket is carried on a shaft with a pair of coil springs housed in a receptacle separated from the duct so that broken spring parts do not enter the fluid in the housing.

Abstract: An insulation piece for joining with a similar piece to surround a pipe elbow of a larger diameter such as greater than 9 inches outside diameter is formed by cutting from a block of the insulation material.