Abstract: A check valve for use in an air flow line to convey pressurized air to unload a tank trailer, railroad car, or other conveying facility. It includes a housing, having a valve seat, a check valve for seating upon the valve seat, a bushing holding the valve stem for the check valve, with the bushing having a channel therein, through which the valve stem locates, and contains a spring therein that is totally encapsulated within the bushing chamber, during usage. The housing is internally contoured to enhance the flow of pressurized air therethrough.