Abstract: A closure device (4) is used to seal an opening of a vessel (6), while providing access to the interior of the vessel. The closure device automatically releases gas and/or toxic vapor from the sealed vessel to protect the operator from harmful vapor without requiring the operator to manually actuate a valve or other mechanism prior to removing the vessel from the closure device. The closure device is constructed so the interior of the vessel can be pressurized while maintaining a pressure seal against the vessel opening, and the vessel can be cannulated without overpressurizing the vessel interior.

Abstract: A closure device (4) and a method for sealing an opening of a vessel (6), while providing access to the interior of the vessel. The device also provides a method for automatically releasing gas and/or toxic vapor from the sealed vessel to protect the operator from harmful vapor without requiring the operator to manually actuate a valve or other mechanism prior to removing the vessel from the closure device. In addition, the device provides a method for pressurizing the interior of the vessel while maintaining a pressure seal against the vessel opening and a method for cannulating the vessel without overpressurizing the vessel interior.