ENCLOSED VAPOR DEGREASING SYSTEMS

摘要

Historically, vapor degreasing has been the cleaning process of choice for the majority of manufacturers. It is primarily used for batch cleaning of parts in such industries as general metalworking, automotive components, aerospace, and electronics. Vapor degreasing traditionally used CFC-113 and 1,1,1-trichloroethane solvents. Recent developments have forced both manufacturers and chemical companies producing solvent to reexamine current cleaning processes. It was the discovery that these solvents, commonly used in the cleaning process, were responsible for the depletion of the ozone layer that eventually lead to the Montreal Protocol. The Protocol called for a phased withdrawal of these solvents from the world marketplace. In the United States, taxes have been levied on continued use of these solvents and the U.S. EPA now requires warning labels on products that were manufactured using these solvents and placed into commerce. As a result, some solvent manufacturers have announced that they will cease production of these materials. These events have created many problems for manufacturers who rely on the vapor degreasing process. The "magic bullet" (a drop-in replacement solvent) that provides high threshold limit values (TLVs) and the good cleaning characteristics of 1,1,1-trichloroethane and CFC-113 without any ozone-depletion potential does not exist at present. Chemical manufacturers report that if replacements are developed, they will be more costly and perhaps have lower boiling points and lower TLVs. Most chemical companies won't even speculate on when these replacement chemistries might be available. The consensus is, however, that new replacements will not be available before the existing chemistries are phased out. This has mandated industry to seek alternatives to the conventional vapor degreasing process and it must choose from technologies and chemistries that are currently available.