Metal Finishing Guide Book

2012-2013

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Table III. Incremental Value of Upgradesa NESHAP Option or Control Combination 1 2 3 4 5 6 7 8 9 10 aAll Primary Control Option Freeboard ration = 1 30% Freeboard refrigeration 30% Freeboard refrigeration 30% Freeboard ration = 1 30% Freeboard refrigeration 30% Freeboard refrigeration 30% Freeboard refrigeration 30% Freeboard ration = 1 40% Freeboard refrigeration 30% Freeboard ration = 1 30% Secondary Control Option Superheated vapor +30% Superheated vapor +30% = 60% Automatic cover +20% = 50% Superheated vapor +30% Reduced room draft +20% = 50% Freeboard ration = 1 +30% = 60% Dwell time +20% = 50% Reduced room draft +20% Carbon adsorption +30% = 60% Superheated vapor +30% Tertiary Control Option Automatic cover +10% = 70% Reduced room draft +10% = 70% Dwell time +10% = 70% Carbon adsorption +10% = 70% values are approximate, compiled from tests at a number of companies is introduced as the final rinse and all vapors are exhausted after each cycle and passed into a solvent recovery system. With the sealed chamber control of solvent loss exceeds 90%; in other words virtually no solvent escapes. Programmed automated operation permits a variety of cleaning programs including cold or warm solvent dipping, as well as vapor degreasing. Solvent recovery cycles make use of advanced methods of carbon adsorption and hot air desorption. The manufacturer of one such unit, a ���closed open-top degreaser��� with a large cleaning chamber, claims that solvent emission losses average less than 100 lb/yr. Solvent concentrations in the work area of the ���closed open-top��� unit average between 5 and 10 ppm, well below the permissible exposure limits set by OSHA for the chlorinated solvents. Although these ���emissionless��� units can be costly, a number of plants in the U.S. have found them economical because they provide excellent compliance with safety and environmental regulations,conserve solvent, save floor space, and provide excellent parts cleaning performance. Several brands of these ���emissionless��� degreasers are available in North America today. Most producers and distributors of chlorinated solvents provide support for solvent users. The Responsible Care initiative of the Chemical Manufacturers Association, to which all solvent producers subscribe, and the Responsible Distribution code of the National Association of Chemical Distributors require members to share product stewardship information, safety training, and regulatory data with customers. When selecting a supplier be sure to review what kind of support is provided. 111

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