Metal hydride fires and fire suppression agents

Most metal hydrides are pyrophoric and water-reactive. Summaries of metal hydride fire incidents are presented to illustrate ignition scenarios, threats to personnel and equipment, and fire suppression experiences. Met-L-X™, a sodium chloride-based, certified, Class D fire suppression agent, has successfully extinguished some metal hydride fires by coating the hydride and excluding air access. However, the still hot hydride is prone to re-ignition upon surface disturbance, such as may be necessary during disposal. Previously reported testing of various Class D agents and moist sand for sodium hydride fires is reviewed here along with certification and ad hoc testing of existing Class D agents and recent testing of a new candidate Class D agent. Hydride explosibility testing is also briefly summarized. Additional fire and explosibility tests, as well as suppression agent reactivity evaluations, are recommended.