UN 2921 — Corrosive solid, flammable, n.o.s.
Placard: Corrosive. ERG Guide 134. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2921 is Corrosive solid, flammable, n.o.s., a broad hazardous materials entry for solids that are corrosive and flammable. Because it is n.o.s., responders should not assume a single chemical behavior without the SDS or shipping papers.
Hazard overview: UN 2921 combines corrosive and flammable hazards. The material may injure responders through contact, inhalation or fire gases, and the severity depends on the actual product shipped under this entry.
Response guidance: For a UN 2921 incident, isolate the area, remove ignition sources when flammable vapors or dust may be present, stay upwind and prevent runoff from drains. Select suppression and control tactics only after checking ERG 134, SDS and monitoring results.
Firefighter training notes: Train responders to treat Corrosive solid, flammable, n.o.s. as a variable n.o.s. entry. Crews should identify the actual product from shipping papers, SDS, container labels and monitoring before committing personnel close to the release.
Regulatory context: Corrosive solid, flammable, n.o.s. is regulated by its DOT hazard class and subsidiary risks shown on the shipping paper. The specific chemical name, packing group and emergency contact should be verified before final cleanup or transfer decisions.
Storage & handling: Store Corrosive solid, flammable, n.o.s. according to the actual product SDS. Keep containers closed, labeled and segregated from incompatible materials such as oxidizers, acids, bases, water-reactive substances or ignition sources as applicable.
UN 2921 Quick Details
Common Hazards of UN 2921
- This n.o.s. entry covers variable solid materials; the exact product must be confirmed from shipping papers and SDS.
- Material may ignite from heat, sparks or flames.
- Dust, smoke or decomposition products may be hazardous if inhaled.
- Liquid or dust contact can cause severe skin and eye injury.
- Fire may produce irritating, corrosive or toxic gases.
- Runoff may spread contamination and create environmental hazards.
- Some products under this entry may react with water, metals or other incompatible materials.
- Containers may rupture or intensify the incident when heated.
Chemical Identity & Physical Properties
UN 2921 is normally a solid, but color, odor, vapor behavior, dust generation and water reactivity vary by the actual product. Treat unidentified releases as hazardous until confirmed.
| Appearance | Variable appearance depending on specific substance; typically a solid material at room temperature that exhibits both corrosive and flammable properties. May range from crystalline to powdered form with varying colors and odors. |
| Flash Point | Variable; typically below 93°C (200°F) for flammable classification |
| Boiling Point | Variable depending on specific substance; decomposes or sublimates in many cases |
| Vapor Density | Variable; many corrosive solids produce heavier-than-air vapors when heated |
| Water Reactivity | Variable; some formulations react with water or generate heat, so confirm SDS before applying water directly. |
Fireground Response Guidance — UN 2921
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing appropriate for splash, dust or vapor exposure. Final glove and suit selection should come from the SDS because breakthrough resistance varies.
Isolation & Evacuation
First Actions for a UN 2921 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream; avoid low areas where vapors may collect.
- Avoid breathing vapors, dust, mist, smoke or fire gases.
- Do not touch damaged containers or spilled material without proper PPE.
- Ventilate confined spaces only if trained, equipped and authorized.
- Use ERG, SDS, shipping papers, labels and monitoring results for final tactical decisions.
📋 Copy & Share Field Card
UN 2921 — Corrosive solid, flammable, n.o.s.Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.