Abstract: A method and an apparatus for treating workpieces with a fluid, in particular for cleaning metallic workpieces prior to a subsequent heat treatment are disclosed. The workpieces are positioned in an air-tight washing vessel. The vessel is filled with an immersion bath substantially covering the workpieces and having a temperature of between 50.degree. C. and 90.degree. C. After closing the washing vessel it is evacuated down to a vacuum having a pressure being below the saturation vapor pressure of the fluid at the prevailing temperature. Thus, the fluid starts to boil although its temperature is substantially below the boiling temperature of the fluid at atmospheric pressure. After a certain period of time of maintaining the vacuum and the boiling, the vacuum is relieved and the bath is discharged.

Abstract: A method and an apparatus for treating workpieces with a fluid, in particular for cleaning metallic workpieces prior to a subsequent heat treatment are disclosed. According to claimed method the workpieces are positioned in a washing vessel and are entirely overflowed with a pressureless swell of a treating fluid. After a certain period of time, a discharge opening in the vessel is closed so that an immersion bath is filled in. When the workpieces are entirely immersed in the treating fluid, the fluid is agitated by means of air bubbles. During subsequent bath discharge the workpieces are continuously overflowed by the treating fluid in order to avoid chemical reactions with the ambient atmosphere. Finally, the workpieces are dried by means of a vacuum dryer.