What is vapour degreasing?
Vapour degreasing suspends parts in the hot vapour of a boiling solvent. The vapour condenses on the cooler part, dissolves oil and drips back into the tank, leaving the part dry with no rinse. Traditionally run on trichloroethylene, it is being displaced by aqueous cleaning.
The process is elegant: the solvent distils itself continuously, so parts always meet clean condensate, and they leave dry and residue-free. That is why it dominated precision cleaning for so long.
The problems are the solvent, not the principle. Chlorinated solvents such as TCE are carcinogenic and heavily regulated; the vapour zone must be held at 90–100 °C; and evaporative loss, drag-out and disposal all carry cost and exposure risk.
Modern replacements go one of two ways: an aqueous line with wash, rinse and dry stages, or a sealed vacuum degreaser running a modified alcohol. For most Indian engineering plants the aqueous route is cheaper to install and far simpler to comply with.
