The present disclosure provides a valve for a respiratory bypass conduit, the valve further comprised of an inner frame that provides rigidity to a flexible outer seal. The inner frame has guiding flanges to guide the valve within he conduit, and a hinge portion to be secured within a slot of the conduit. Together, the hinge and the guiding flanged help the valve move from a first position to a second position. The present disclosure also provides for a method of assembling the valve for respiratory bypass conduit, whereby the inner frame is aligned with and inserted into the outer seal until a peripheral gap of the outer seal substantially houses the inner frame and an inner periphery of the inner frame surrounds a recessed portion of the outer seal to secure the outer seal in the correct orientation relative to the inner frame.