A tube extends through an attachment section and defines a vapor passageway. A housing is supported to the attachment section for movement between several positions relative to the attachment section. The housing defines a float chamber below the tube. A valve seat portion is located within the float chamber and has an engagement part, a sleeve part and a seat surface. The engagement part is connected to the housing. The sleeve part telescopically engages the tube and is movable along the tube with the housing. The valve seat portion defines a central bore open to the vapor passageway and the seat surface. The float moves within the float chamber. When to fluid enters the float chamber the float floats up against the seat surface closing off the central bore and the vapor passageway. In the absence of fluid the float moves downward exposing the seat surface.