HF is a unique inorganic acid and does not completely dissociate. Therefore, researchers should allow sufficient time for the neutralizing agents to neutralize the acid.
Properly dispose of waste from HF cleanup work using polyethylene containers.
HF spillage should be contained and avoid allowing the spill to go down the drainage sink in the fume hood, if possible. If necessary, neutralized liquid within the fume hood should be diluted with copious amount of running water.
For detailed spill response, please review EHS spill response guidelines.
A spill containing HF should be neutralized with calcium hydroxide, calcium carbonate, or other magnesium salts.
- Spill kits containing silica such as sand, vermiculite, Floor-Dri or kitty litter should not be used because HF reacts with silica to produce a toxic silicon tetrafluoride (SiF4) gas.
- Commercially available HF specific spill kits include spill absorbent materials such as 3M universal adsorbent, HF Acid-Eater (NPS Corp) or HF Spill Tamer (JT Baker/Mallinckrodt), Kolor-Safe® Kolor-Lock powder, and PIG® HF neutralizer. Silver shield gloves with inner double Nitrile gloves can be used for spill cleanup work.
Depiction of Commercially Available Spill Kit
- The HF spill kit should also include thick chemical resistant gloves (2 pairs, 14 mil or higher thickness), chemical splash goggles (at least 1), polyethylene bags (2 bags, 4 mil thickness). Commercially available spill kits may also include: HF spill adsorbent/neutralizer materials, 2 aprons, 2 pairs of gloves, hazmat boot covers, 2 pairs of goggles, MSDS and cleanup instructions.
- Calcium based neutralizers convert HF to an insoluble calcium fluoride salt.
- Small amounts of HF spill in the fume hood (<2 ml, 40% or less) can be absorbed using calcium carbonate antacid tablets (15 tablets, 500 mg each). Dilute the spilled area with water and then neutralize the acid cautiously using crushed tablets.
- HF with concentrations greater than 40% will generate fumes in air. Therefore, the spilled area must be carefully and rapidly diluted to less than 40% concentration with water and then neutralized using calcium hydroxide slurry or other commercial spill materials. The effectiveness of the neutralization should be checked with pH paper.
- HF cleanup waste should be collected separately and EHS should be contacted for disposal.
- Researchers using boric acid for HF spill cleanup and neutralization should collect the resulting solution for disposal by EHS.
- Any HF spill greater than 250 ml outside of a fume hood should be treated as a large spill.
- Call 911 for any large spills (if the spill is greater than 250 ml HF outside of a fume hood).
- See risk reduction assessment table for additional detail.