☣️ DOT HAZMAT CLASS 4
Flammable Solids
Materials that ignite easily, react with water, or spontaneously combust—avoid incompatible actions.
🧯☣️
⚠️ Training/quick-reference only. For real incidents, follow your SOP/SOG and the current ERG.
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Common hazards (high level)
- Rapid ignition and difficult extinguishment
- Water-reactive hazards (some products)
- Self-heating / spontaneous ignition
How to recognize
- Placards indicating Class 4.x
- Powders, granules, or packaged solids
- Heat/smoke without obvious flame source
First actions (before Hazmat team)
- Identify product markings; avoid incompatible extinguishing agents
- Isolate and stage upwind
- Request Hazmat for unknown reactive solids
- Use ERG + SOP for extinguishment guidance
- Prepare for rekindle and extended operations
What NOT to do
- Do not apply water to unknown reactive solids
- Do not disturb powders without PPE/controls
- Do not assume normal Class A behavior
Common examples
Reactive metals (varies)Self-heating materialsCertain powdersMatches (varies)
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FAQ
Certain solids react with water to release heat or flammable/toxic gases—product-specific guidance is essential.
Isolate, identify from distance, request Hazmat, consult ERG/SOP before committing.
Yes—self-heating and deep-seated involvement can cause repeated ignition.
Sources (high level): DOT/PHMSA class & marking concepts, NFPA 704 overview concepts, and ERG usage principles. This guide does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.