A molded, one piece, generally Y-shaped, flexible, tubular valve body formed of a fabric reinforced elastomer. The valve body is mounted in a housing which also supports a roller type pinching mechanism to open and close the legs of the Y-shaped valve body. A nose portion is formed as part of the valve body at the juncture of the legs of the valve body and moves in the direction of the leg being pinched closed. The nose portion is reinforced by a stiff arcuate shaped insert. The configuration of the valve body and its mounting on the housing permits flexing of the portion of the valve body upstream of the nose portion during opening and closing of the leg portions of the valve body. This construction permits the pinching elements to be positioned close to the juncture of the legs of the Y-shaped valve body, thus reducing the volume of the plug of material that is trapped in the branch leg upon closing thereof.