UN 0492 — Signals, railway track, explosive
Placard: Explosive 1.3G. ERG Guide 112. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 0492 is Signals, railway track, explosive, a Class 1.3 pyrotechnic or signal entry assigned to ERG Guide 112. It is mainly a fire and deflagration hazard with intense heat, smoke and possible fragment projection.
Hazard overview: UN 0492 may burn intensely, produce smoke or bright flame, rupture casings and scatter burning fragments. Pyrotechnic or signal compositions can make suppression difficult, so responders should avoid close approach and rely on incident command direction.
Response guidance: For a UN 0492 incident, responders should confirm the division and product using markings, shipping papers and ERG Guide 112. Isolate the area, stay upwind, avoid smoke and radiant heat, and protect exposures only from a safe distance under local SOP.
Firefighter training notes: Training should emphasize pyrotechnic, propellant or explosive fire behavior, smoke hazards, fragment potential and the risk of escalating nearby explosive articles. Common errors include approaching through smoke, disturbing damaged packages and failing to expand isolation when fire spreads.
Regulatory context: Signals, railway track, explosive is regulated as a Class 1 explosive hazardous material. Transportation, storage, quantity limits, fire code controls and reporting requirements may vary by jurisdiction. Responders should verify current requirements through shipping papers, SDS or product documents and applicable DOT, ATF, OSHA, NFPA, military, state or local authority guidance.
Storage & handling: Signals, railway track, explosive should be stored only in approved packaging, magazines or authorized explosive storage areas, separated from ignition sources, incompatible materials and unauthorized access. Packages should be protected from heat, impact, friction, moisture where relevant and physical damage according to product documentation and applicable explosive storage regulations.
UN 0492 Quick Details
Common Hazards of UN 0492
- Fire and deflagration hazard; pyrotechnic or signal articles may burn with intense heat, smoke and localized fragment projection.
- Not normally a mass explosion hazard when transported as classified, but bulk fire can escalate rapidly.
- Smoke may contain irritating or toxic combustion products.
- Heated casings may rupture or scatter burning fragments.
- Nearby combustibles, ammunition or pyrotechnics may be ignited.
- Large quantities may require expanded isolation and remote operations.
Chemical Identity & Physical Properties
Small explosive devices, typically metal or plastic casings containing primary explosives, designed to be placed on railroad tracks to produce audible warning signals.
| Also known as | Railway track signalsRailroad track torpedoesTrack warning devicesDetonating railway signalsTrack detonators |
| Appearance | Small explosive devices, typically metal or plastic casings containing primary explosives, designed to be placed on railroad tracks to produce audible warning signals. |
| Flash Point | Not applicable (explosive article) |
| Boiling Point | Not applicable (explosive article) |
| Vapor Density | Not applicable (solid explosive device) |
| Water Reactivity | No significant reaction with water under normal conditions |
Fireground Response Guidance — UN 0492
Extinguishing Media
PPE Requirements
Responders should use structural firefighting gear with SCBA for smoke or fire exposure and maintain standoff distance from burning articles or packages. PPE does not replace evacuation if additional explosives or large quantities are involved.
Isolation & Evacuation
First Actions for a UN 0492 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away and deny entry.
- Stage upwind and avoid smoke from burning pyrotechnic, propellant or explosive material.
- Eliminate ignition sources if it is safe to do so.
- Isolate the area and check for nearby explosives, ammunition, propellants or pyrotechnic articles.
- Protect exposures only from a safe distance if directed by incident command.
- Use ERG Guide 112, shipping papers and incident command to set isolation and evacuation distances.
📋 Copy & Share Field Card
UN 0492 — Signals, railway track, explosiveUse 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.