Vapor Degreasing

Definition - What does Vapor Degreasing mean?

Vapor degreasing is a surface-finishing process. It involves solvents in vapor form to cleanse the workpiece in preparation for further finishing operations. It is a solvent cleaning procedure for the removal of soluble contamination or oils from a variety of metallic and nonmetallic parts.

Benefits of vapor degreasing include:

  • Can be used on electronic parts to remove excess oil, grease, wax and other non-water soluble particles
  • Cleans and prepares part surfaces for various finishing processes like painting, welding, soldering and bonding
  • Does not cause part oxidation or water spots
  • No solvent emitted with vacuum degreasers

One disadvantage of vapor degreasers is that they have a high cost and low production rate.

Corrosionpedia explains Vapor Degreasing

Vapor degreasing is a surface-cleaning process that uses solvent vapors to wash oils and other contaminants off of metal and plastic parts to be used in manufacturing. It is especially effective for cleaning small parts and those containing deep recesses that are difficult to reach by hand.

The principle of vapor degreasing is scrubbing the part with hot solvent vapors. These vapors condense on the part at a sufficient rate to form liquid flow, which dissolves and washes the contamination away as the condensed solvent drains by gravity. Sometimes it is not possible to wash the heavy contamination away by vapor degreasing. In such cases an acetone scrub is the first step to remove contamination, followed by vapor degreasing to remove residual oils, greases, etc. Vapor degreasing requires both the proper type of solvent and degreasing equipment.

The solvents used must meet the following properties:

  • High solvency of oils, greases and other contamination
  • Nonflammable, nonexplosive and nonreactive under conditions of use
  • High vapor density compared to air and low rate of diffusion into air to reduce loss
  • Low heat of vaporization and specific heat to maximize condensation and minimize heat consumption
  • Chemical stability and noncorrosiveness
  • Safety in operation
  • Boiling point low enough for easy distillation and high enough for easy condensation
  • Conformance to air pollution control legislation

The most common solvents used for vapor degreasing are:

  • Methyl chloroform (1,1,1-trichloroethane)
  • Methylene chloride (dichloromethane)
  • Perchloroethylene (tetrachloroethylene)
  • Trichloroethylene
  • Trichlorotrifluoroethane

However, the first two have been banned due to health, safety and environmental reasons.

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