Vapor degreasing

Solvent Gleaning. Solvent cleaning employs the natural solubilizing properties of various nonaqueous solvents or blends of solvents. Either 100% solvents or aqueous emulsions of solvents can be used. AppHcation is typically by immersion, hand appHcation, or via a vapor degreaser machine. 

Vapor Degreasing. In vapor degreasing, the solvent is vaporized and the cold part is suspended in the vapor stream. The solvent condenses on the part, and the hquid dissolves and flushes dirt, grease, and other contaminants off the surface. The part remains in the vapor until it is heated to the... 

Trichloroethane and other chlorinated solvents are used for vapor degreasing (84—90). Other uses include cold metal cleaning, printed ckcuit board cleaning, and as a solvent for inks, coatings, adhesives, and aerosols. 1,1,1-Trichloroethane is an excellent solvent for development of photoresist polymers used in printed ckcuit board manufacture (see Integrated circuits Photoconductivepolymers). 

The demand for trichloroethylene grew steadily until 1970. Since that time trichloroethylene has been a less desirable solvent because of restrictions on emissions under air pollution legislation and the passage of the Occupational Safety and Health Act. Whereas previously the principal use of trichloroethylene was for vapor degreasing, currentiy 1,1,1-trichloroethane is the most used solvent for vapor degreasing. The restrictions on production of 1,1,1-trichloroethane [71-55-6] from the 1990 Amendments to the Montreal Protocol on substances that deplete the stratospheric ozone and the U.S. 

Clean Air Act 1990 Amendments will lead to a phase out of 1,1,1-trichloroethane by the year 2005, which in turn will likely result in a slight resurgence of trichloroethylene in vapor-degreasing appHcations. The total production, however, will probably stay relatively low because regulations will require equipment designed to assure minimum emissions. 

The details are then removed from the tool for anodizing and priming. They are first processed through a multi-tank anodize line that consists of a vapor degreaser... 

Honeycomb core parts are usually supplied from the core manufacturer clean and packaged in such a way that additional cleaning is not necessary. If this is not the case or if secondary machining is necessary, the core detail is cleaned by vapor degreasing or emulsion cleaning to remove organic contaminants. 

Chlorinated solvent vapor degreasers can be replaced with high pressure power washers which do not generate spent solvent hazardous wastes or toxic fugitive emissions. 

FIGURE 10.22 Predicted versus measured capture efficiency of vapor degreasers under operating conditions. 

The end-use pattern of trichloroethylene in the United States was estimated as follows (CMR 1986) vapor degreasing of fabricated metal parts, 80% chemical intermediates, 5% miscellaneous uses, 5% and exports, 10%. The most important use of trichloroethylene, vapor degreasing of metal parts, is closely associated with the automotive and metals industries (CMR 1983). 

Production, Import/Export, Use, Release, and Disposal. Humans are at risk of exposure to trichloroethylene because of its widespread use and distribution in the environment. Production, import, and use of the chemical are known to be relatively high, but recent quantitative data were not available (HSDB 1994). Trichloroethylene is released to the atmosphere mainly through its use in vapor degreasing operations (EPA 1985e). Landfills can be a concentrated source of trichloroethylene on a local scale. It is also released to surface water and land in sewage sludges and industrial liquid or solid waste. Trichloroethylene is... 

Ulander A, Selden A, Ahlborg G. 1992. Assessment of intermittent trichloroethylene exposure in vapor degreasing. Am Ind Hyg Assoc J 53 742-743. 

Wadden RA, Scheff PA, Franke JE. 1989. Emission factors for trichloroethylene vapor degreasers. Am Ind Hyg Assoc J 50 496-500. 

Uses Organic synthesis vapor degreasing and cold cleaning solvent for fabricated metal parts textile processing aerosol propellants synthesis of fluoropolymers production of various coatings and inks may be ingredient in adhesives, cutting oils, and aerosol formulations pesticide. 

Small job shop used trichloroethane (TCA) in a vapor degreaser Converted degreaser into a water immersion cleaning unit... 

Small job shop used TCA in a vapor degreaser to clean aluminum metal parts Firm converted to water-based cleaning system... 

Unlike cold-cleaners, vapor degreasers lose relatively small amounts of solvent as solid waste or liquid drag-out. Most emissions are due to vapor loss and the loss level is highly dependent on operator and operating conditions. Solvent losses for a poorly operated open-top vapor degreaser may be eight or more times greater than for a well-operated unit (Branson Ultrasonics Corporation, 1988). 

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