An experienced researcher with 30+ years of laboratory experience (including working with air-sensitive compounds) was disposing of a small vial of catalyst and hydride powder left in the laboratory by a post-doc. The researcher emptied the vial into a container of mineral oil inside a glove box, but a small amount of the hydride powder adhered to the wall of the vial. The vial was then removed from the glove box and brought over to a tall waste jar in the laboratory that contained isopropanol. (Isopropanol is the first (slowest-acting) pacifier used when deactivating pyrophoric hydrides.) The vial was opened and inverted over the isopropanol jar and the residue powder was tapped into the jar. There was a "small flash of flame" that quickly extinguished itself.
The project team concluded that the jar contained a sufficient vapor pressure of isopropanol to ignite when it came into contact with the decomposing hydride. The lesson learned was that hydrides react rapidly in air and can lead to combustion of any organic vapor that might be present nearby. Thus, the project team adopted a procedure that all hydrides must be submerged in mineral oil before they are removed from the glove box to prevent exposure to air before isopropanol treatment. Since this procedure was adopted for pacification/disposal of hydrides, there have been no more incidents or near-misses of this type in the laboratory.