What Is Vapour Degreasing?
Vapour degreasing has become a generic term used for any cleaning process that uses a hot solvent as the cleaning medium. However, more accurately, it is the simplest, and traditionally, the most commonly used, solvent cleaning process.
True vapour degreasing uses the vapour generated when a solvent, such as perchloroethylene, is heated to its boiling point. When the hot vapour encounters an item at a lower temperature, such as a component to be cleaned, it condenses and runs down the surface, dissolving any contamination it comes into contact with. The latent heat released when the vapour condenses gradually heats up the item until it reaches the same temperature as the vapour, at which point, condensing, and thus cleaning, stops. When the component is removed from the solvent vapour, the heat retained by the item evaporates the thin film of liquid solvent, leaving the part clean and dry.
Vapour degreasing is simple, fast and effective for cleaning items with simple geometry and relatively high thermal mass. It is not so effective on complex items with blind holes, cavities etc., or on items that heat up very quickly e.g. thin aluminium sheet. In these instances, cleaning by immersion into liquid solvent, either at the boiling point or irradiated with ultrasonic energy, is a more effective cleaning process.