A sealed container provided with a valve opening and a resilient valve member self-biased into closing position. The valve is manually openable by a lever which is held in the open position by a rigid fuse-like element which melts after being subjected to sterilizing temperatures long enough to sterilize the container and its contents. The valve then closes sealing the container. The valve and a gasket between the container lid and base will permit leakage out of the box to permit the withdrawal of steam from the container when a vacuum is applied to the container exterior but will prevent reverse flow so that a vacuum is maintained within the container once one is created. The vacuum may be released by opening the valve, which simultaneously cocks it for the next sterilizing operation.
An alternate approach includes a disposable, resilient valve member which plugs into a hole in the wall of the container and covers a valve orifice into the container. A washer-like fuse element fits into the valve member to bias it into an open position. When the fuse melts after sterilization, the valve member will snap into closed position.