Precision cleaning

The replacement of toxic solvents used in professional garment dry cleaning and critical/precision cleaning of manufactured goods... 

With a reformer, also natural gas, MeOH, biogas, coal gas etc. CO precision cleaning may be necessary. 

Precision cleaning Cleaning of sensitive parts such as optical devices and gyroscopes that have ultra-high cleanliness standards Organic residues, particulates... 

Thus, the above findings149) indicate that the first stage of the initiation of the epoxy compound polymerization under the action of the TA even in precision-cleaned systems may take place by the trimolecular mechanism to give quaternary ammonium alcoholates owing to impurity quantities of the proton donor or other electrophilic particles in the system. This reaction will not occur in the absence of such impurities. Upon appearance of the hydroxyl groups in the system due to the chain transfer to the counterion (see Sect. 3.3.3) the reaction according to Scheme (33) with participation of the unsaturated alcohol becomes the main source of the active growing sites. 

The electronics industry, which formerly used large quantities of CFCs as precision cleaning agents, has also switched to other chemicals. For example, IBM s San Jose manufacturing facility, which was the largest industrial emitter of CFCs,... 

Pirrotia, R. and Pava, T., Supercritical carbon dioxide— performance with potential. Precision Cleaning, 11 37 (1994)... 

Agopovich, J. W., Fluorocarbons and supercritical carbon dioxide service niche needs. Precision Cleaning, 111 15 (1995)... 

Spall, W. D., Supercritical carbon dioxide precision cleaning for solvent and waste reduction, Int. J. Environmentally Conscious Design and Manufacture, 2 81 (1993)... 

Williams, S. B Laintz, K. E., Barton, J. C., and Spall, W. D., Elimination of Solvents and Waste by Supercritical Caibon Dioxide in Precision Cleaning, Los Alamos National Laboratory Report, LAUR-94-3 313 (1994)... 

Spall, W. D., Supercritical Caibon Dioxide Precision Cleaning for Solvent and Waste Reduction, Int l. J. Environ. Conscious Design Manuf, 1(2-4) 1-10 (1992)... 

Sipitkowski, J. M., Design for Cleanability Part Geometry and Surface Finish, Precision Cleaning, l(l) 55-57 (Nov./Dec. 1993)... 

Precision Cleaning With Supercritical Fluid A Case Study... 

Many of the commonly used solvents for precision cleaning are being eliminated due to their suspected involvement in reduction of the earth s ozone layer. Production of these chemicals, known as ozone depleting substances (ODS), is being eliminated by an international treaty known as the Montreal Protocol. This is an international agreement, first proposed in 1987 and entered into force in 1989, which limits production of chlorofluorocarbons (CFCs) and halons due to concerns that these substances were damaging the earth s ozone layer. The Montreal Protocol was modified in 1990 and again in 1992 to completely eliminate the production of chlorofluorocarbons, carbon tetrachloride, methyl chloroform (1,1,1 -trichloroethane) and halons by 1996. 

Supercritical fluids were identified in early 1989 as a possible CFC replacement for certain niche applications at Honeywell Space Systems. At that time there was very limited data on either the application of supercritical fluids for precision cleaning or compatibility studies with materials common to the aerospace industry. 

In summary, the problems associated with this system were related to the fact that supercritical fluids had been used previously for batch extraction processes and there had been no significant development to this time of supercritical fluid extractors for the specific application of precision cleaning. These problems were exacerbated by an unwillingness of the vendors to discuss many of the problems they had already encountered and solved, based on proprietary process concerns. 

In summary, the road between initial development of alternative cleaning processes and implementation of those processes into the production environment is often long and full of potential potholes. This is especially true when implementing those processes for precision cleaning where the parts are typically complex and expensive, and the results of changes are not immediately apparent. 

Several important lessons were learned during this project. One of the first and most important was related to the equipment necessary for performing precision cleaning using supercritical fluid. The... 

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