Abstract: A system and method for cleaning an article with cleaning fluid comprising a liquified gas, preferably carbon dioxide, maintained at a pressure elevated above atmospheric pressure in the wash chamber of a pressure vessel. A basket holding the article is rotated in the wash chamber by a drive shaft passing through a wall of the pressure vessel, and a seal mechanism for this passage prevents escape of the cleaning fluid. The seal mechanism includes a first seal component adjacent to the wash chamber and a second seal component outboard of the first seal component to provide a sealant chamber in which a pressurized sealant fluid is provided such that a pressure differential across the first seal component is substantially less than the pressure differential between the wash chamber and atmospheric pressure The sealant fluid may be a gaseous component or a liquid component of the cleaning fluid. Fluid and control systems are provided for automating washing, rinsing and sealing operations.