Metal Finishing Guide Book

2012 Organic Finishing Guidebook Issue

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Page 23 of 331

Fig. 2. Totally enclosed vapor degreaser can meet stringent environmental regulations. boiling temperature of the solvent): This promotes more thorough drying of the work before it is removed from the degreaser. • Carbon adsorption equipment in the ventilation system connected with the degreaser. In addition vapor degreasing operators must employ an automated hoist or conveyor that carries parts at a controlled speed of 11 fpm or less through the com- plete cleaning cycle. Each of these procedures used alone will reduce solvent loss by a respectable amount while combining two or three procedures reduces loss even further. For example creating a freeboard ratio of 1.0 in an open-top degreaser will reduce loss by 30 to 40% over the traditional process. Combining an increased freeboard ra- tio with superheated vapor or reduced room draft increases the control level to 60%. And in most cases, if a user combines three of the procedures, this will bring the control up to 70%. Table III illustrates how these incremental im- provements can be brought about. Many companies have found it cost effective to adopt one of the new de- greasers, which have no air/vapor interface. These sealed and virtually emis- sionless units were first introduced in Europe to meet the stringent environ- mental regulations of some countries (see Fig. 2). Typically these degreasers perform the cleaning operation in a sealed cham- ber into which solvent is introduced after the chamber in closed. Solvent vapor 22

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