Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 92 of 707

Figure 2: Typical desorption schematic. ENGINEERED SOLUTIONS All degreasing equipment and solvent manufacturers encourage users to reduce emissions and workplace exposure limits to the lowest possible level. Later-generation degreasers were designed to comply with gov- ernment regulations, such as NESHAP, and offer solvent conserva- tion/operational efficiency. The older-generation degreasers still in use sometimes lack the elements of the newer designs. But with or without some of the NESHAP stated equipment control devices: • the sheer size of the units; • the type of work being cleaned; • the volume of work to be cleaned; • the process itself; • other extenuating items; .......can lead to emissive ppm levels that may exceed impending enforce- ment levels. Past emissive limits and workplace exposure levels will become hard- er to meet for some users/some systems. CURRENT TECHNOLOGY For those solvent users who have switched to nPB, carbon adsorption technology is now available that allows the recovery of emissive losses and lowers the ambient ppm levels in the workplace. To the nPB user, this means capturing emissive losses currently or nor- mally lost to the atmosphere. The capture and recovery of the emissions 91

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