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Industry has continued to use fluoride-bearing fluxes for over 60 years, despite the many known hazards and toxic effects of fluorides. There are two primary reasons for this:
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Fluoride-bearing fluxes perform excellently in many applications, providing little incentive for change.
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It was almost universally held that developing acceptable fluoride-free brazing flux was impossible. This resulted in little to no serious R&D effort being devoted to fluoride-free brazing flux development.
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Superior Flux & Mfg. Co. has developed fluoride-free fluxes,
Superior Nos. 650 and 652. These fluxes exhibits excellent brazing characteristics when used with copper, gold and select ferrous alloy base metals, using cadmium-free, silver BAg alloys, phos-copper alloys, and gold alloy filler metals.
When cadmium, a carcinogen, was removed from brazing alloys, the brazing process was made safer. The removal of fluoride continues this trend toward a safer and more environmentally-friendly brazing process:
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1. Operator Safety and Improved Workplace Air Quality: Removing fluorides from fluxes eliminates the active ingredient responsible for “flux sores” and damage to the fingernails. Preliminary results from toxicological tests on Superior Nos. 650 and 652 and the fluoride-bearing brazing flux of a major competitor show the following:
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DERMATOLOGICAL TOXICOLOGY TEST RESULTS (SUMMARY)
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Superior Nos. 650 and 652 Fluoride-Free Flux |
Conventional Fluoride-Bearing Flux |
| Primary Dermal Irritation Index (PDII) |
2.3 |
5.9 |
| Classification |
Not a primary irritant. |
A primary irritant. |
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Non-corrosive to skin. |
Corrosive to skin. |
Moreover, at brazing temperatures, fluoride-bearing fluxes release toxic boron-trifluoride and hydrogen-fluoride gases. Exposure limits for these two gases are shown below:
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ACGIH TWA-TLV |
OSHA TWA PEL |
NIOSH TWA-REL |
OSHA Label |
DOT Label |
| Boron Trifluoride (BF3) |
1 ppm |
1 ppm |
1 ppm |
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Poison |
| Hydrogen Fluoride (HF) |
3 ppm |
3 ppm |
3 ppm |
Toxic |
Corrosive |
These gases and fumes cause both acute and long-term deterioration of the respiratory system and the skeletal structure (bones).
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2. Plant Water Effluents: Excessive fluoride levels in drinking water can pose long-term health hazards. The approach of municipalities/states to acceptable fluoride levels in water has become more stringent. Today, many regions experiencing water shortages are making the demand for clean water a greater priority. Manufacturing facilities affecting these levels are being watched and asked to lower the fluoride content of the effluent that is being disposed into the local water supply.
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