Hazardous Materials Storage, Handling, and Incompatibility Management
This domain covers what happens between receiving a hazardous material and shipping it out: segregation, containment, container condition, and the housekeeping regulators cite most often. Items usually describe a storage room or transfer operation and ask what is wrong.
Segregation logic
Incompatibility is about what materials do when they meet, not whether they share a hazard class. Acids with cyanides or sulfides release HCN or H2S; hypochlorite with acid releases chlorine; oxidizers feed fires involving flammables; water-reactives such as alkali metals and calcium carbide must be kept away from sprinkler water and aqueous solutions. Organic peroxides need isolated, temperature-controlled storage. Post a segregation chart and verify it against the SDS.
Containment and containers
Secondary containment is typically sized for 110% of the largest container or 10% of aggregate volume, whichever is greater. Containers stay closed except when material is added or removed, are inspected weekly, and carry accumulation start dates where RCRA applies.
Flammable liquids
NFPA 30 Class I liquids have a flash point below 37.8 °C (100 °F): IA below 22.8 °C with boiling point below 37.8 °C, IB below 22.8 °C with boiling point at or above 37.8 °C, IC from 22.8 to 37.8 °C. Bond and ground containers during transfer and control ignition sources, including forklifts and portable heaters.
Worked example
A room holds 20 L of nitric acid, four 200 L drums of toluene, and a 25 kg drum of sodium cyanide on one pallet. Three failures: cyanide where acid could reach it during a spill (HCN generation); oxidizer and flammable in shared containment without separation; no secondary containment for the drums. Fix by isolating the cyanide in a dry, acid-free cabinet, separating the acid, and providing at least 220 L of diked volume.
Traps
Treating "same hazard class" as "compatible"; overlooking solid oxidizing salts; forgetting containment for powders; missing the dating requirement that starts the accumulation clock.