A closed 20-mL glass scintillation vial containing approximately 5 grams of an aluminum hydride compound ruptured and shattered, likely due to pressure buildup after 6 weeks of storage. The glass vial with aluminum hydride compound was stored inside a closed plastic box. The plastic box with vial was stored within an air-free glove box at room temperature. When the glass vial ruptured, the vial was contained within the plastic box; however, the plastic box door was forced slightly ajar. The ruptured containers and internal materials were fully contained within the glove box. No damage was observed to the glove box and no one was injured. The attached photograph shows the remains of the vial within the plastic box.
- Laboratory Equipment
1. Evaluate any change in normal procedures or conditions for storage of aluminum hydride products. In this case, the aluminum hydride material was typically stored at -35°C in the glove box freezer. However, due to a change in glove boxes, this was no longer an option. Since commercially available aluminum hydride compound is shipped in glass bottles at room temperature, it was assumed that this was considered safe handling. The vial was stable for 6 weeks before the near miss occurred.
2. Limit aluminum hydride materials to small quantities as needed for immediate use. Larger samples have the potential to caused more damage.
3. Do not store aluminum hydride materials for extended periods of time and promptly dispose of any remaining material after use.
4. In-process aluminum hydride material should be stored at lower temperatures (i.e., in a freezer) and in an air-free contained environment (i.e., inside an air-free glove box) to reduce or slow decomposition into volatile materials (e.g., hydrogen, aluminum metal, and similar). In this case, if the aluminum hydride material had been stored in air, it is likely that a fire may have started.
5. Store aluminum hydride material in plastic containers instead of sealed glass containers to avoid catastrophic failure of containment. In this case, it is likely that the decomposition process of the aluminum hydride compound slowly built up pressure sufficient to destroy the glass vial.
Additional discussion about working with reactive metal-hydride materials in the laboratory can be found in the Lessons Learned Corner on this website and in the Hydrogen Safety Best Practices Manual.