The copper used was essentially pure copper; the aluminum was 5005 

 alloy with an H-19 hardness. 



Cleaning and Coating of Heat Exchangers 



The heat exchangers were taken to the Guaranteed Products Division, 

 DG Shelter Products, City of Industry, Calif., for cleaning and for 

 coating of one set of the three types. The procedures were as follows: 



1. Copper tube/copper fin and copper tube/aluminum fin: 



• Cleaner (detergent plus 6% Oakite) , 3 min at 150°F 

 (66°C) 



• Rinse, 2 min at room temperature 



• Deoxidizer (DESMUT) (Oakite LNC containing sulfuric 

 acid) , 10 sec at room temperature 



• Rinse, 2 min at room temperature 



• Cleaner, 3 min at 150°F (66°C) 



• Rinse, 2 min at room temperature 



• Place three copper tube/copper fin heat exchangers and 

 three copper tube/aluminum fin heat exchangers in indi- 

 vidual plastic bags for return to CEL 



• Paint one copper tube/copper fin heat exchanger and one 

 copper tube/aluminum fin heat exchanger with Sherwin 

 Williams H74BC23 POWERCLAD enamel (black) at 150V DC 

 maximum, 2,000 amp 



• Bake painted heat exchangers; dry film thickness of 

 coating, 0.6 mil (0.0015 cm) 



• Place coated heat exchangers in individual plastic 

 bags for return to CEL 



2. Aluminum tube/aluminum fin: 



• Cleaner (detergent plus 6% Oakite), 3 min at 150°F 

 (66°C). 



• Rinse, 2 min at room temperature 



• Caustic etch (4% sodium hydroxide solution) , 4 min at 

 120°F (49°C) 



• Rinse, 2 min at room temperature 



• Deoxidizer (DESMUT) (Oakite LNC containing sulfuric 

 acid) , 1-1/4 min at room temperature 



