A valve permits articles disposed within a sterilizer container to be exposed to an entire sterilization cycle, yet seals the sterilizer container upon completion of the cycle. The valve includes a housing which defines a passage through which fluid can flow between the interior and exterior of the sterilizer container. A sealing member seals the passage after a predetermined number of high and low pressure stages of a sterilization cycle has been completed. A cam member is reciprocated as the high and low pressure stages of the sterilization cycle are performed, each reciprocation causing the sealing member to move one step closer toward sealing the sterilizer container. Apparatus is provided to permit the valve to be reset for further use of the container.