Q: We are exploring alternate cleaning chemicals for our brazed copper and brass tubing components. The major residue is brazing flux and light oil residue from fabrication. We are currently using nitric acid. What do you recommend?
A: Inorganic brazing flux residue, and the light oils, will be handled nicely by our mild yet effective citric acid based detergents. Depending on your cleaning method, manual or a washer system, we can recommend Citranox® Liquid Acid Cleaner and Detergent or Citrajet® Low-Foam Liquid Acid Cleaner/Rinse, respectively. Both would be at 2% concentrations, followed by thorough rinsing. These acidic detergents are a far safer, less hazardous, less corrosive option than nitric acid. And because these are detergents, rather than a single commodity chemical like a strong acid, synergistic cleaning is engaged allowing for a more thorough critical clean.
For other persistent flux residues we recommend Detergent 8® Low-Foaming Ion-Free Detergent, however, note that Detergent 8 cleaner is typically incompatible with reactive metals like copper and brass.