UN 1381 — Phosphorus, yellow, dry or under water or in solution
Placard: Spontaneously Combustible. ERG Guide 136. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1381 is Phosphorus, yellow, dry or under water or in solution, a self-heating or spontaneously combustible material assigned to ERG Guide 136. The main hazard is hidden heat buildup that can lead to smoldering, open flame or re-ignition.
Hazard overview: UN 1381 presents self-heating, smoldering fire and re-ignition hazards. Disturbing hot material can introduce oxygen and intensify burning, while smoke may contain carbon monoxide and irritating combustion products.
Response guidance: For a UN 1381 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 136. Establish incident command, isolate the area, stay upwind, avoid unnecessary disturbance of powder, piles or damaged packaging, and use only extinguishing agents compatible with the specific material.
Firefighter training notes: Training for UN 1381 should emphasize self-heating, smoldering piles, oxygen exposure during overhaul, thermal monitoring and re-ignition. Common errors include opening hot piles too aggressively and ending operations before deep-seated heat is controlled.
Regulatory context: Phosphorus, yellow, dry or under water or in solution is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Phosphorus, yellow, dry or under water or in solution should be stored to prevent self-heating, oil/moisture contamination where relevant, compacted hot spots and ignition exposure. Keep piles, bales or packages ventilated where appropriate and inspect for heat, odor or smoke according to facility procedures.
UN 1381 Quick Details
Common Hazards of UN 1381
- May self-heat and ignite when damp, oily, contaminated, compacted or stored in bulk.
- Piles, sacks, bales or rolls may retain heat and smolder internally before open flame is visible.
- Disturbing hot material may introduce oxygen and intensify smoldering or flame spread.
- Fire may produce irritating or toxic smoke including carbon monoxide.
- Runoff from fire control may carry organic or oily contamination.
- Large quantities may require prolonged overhaul and thermal monitoring.
- Material may re-ignite after apparent extinguishment.
Chemical Identity & Physical Properties
Waxy, translucent solid ranging from white to yellow in color. Garlic-like odor. Stored under water or inert atmosphere to prevent spontaneous ignition. May be shipped molten.
| Also known as | White phosphorusYellow phosphorusTetraphosphorusP4WP |
| CAS Number | 12185-10-3 |
| Appearance | Waxy, translucent solid ranging from white to yellow in color. Garlic-like odor. Stored under water or inert atmosphere to prevent spontaneous ignition. May be shipped molten. |
| Flash Point | Not applicable (pyrophoric - ignites spontaneously in air at approximately 30C/86F) |
| Boiling Point | 280C (536F) |
| Vapor Density | 4.4 (heavier than air) |
| Water Reactivity | No significant reaction with water; typically stored under water to prevent air exposure and spontaneous ignition |
Fireground Response Guidance — UN 1381
Extinguishing Media
PPE Requirements
Use SCBA for smoke, smoldering material, dust or confined-space operations. Wear protective clothing and gloves appropriate for hot organic material, contaminated runoff and extended overhaul conditions.
Isolation & Evacuation
First Actions for a UN 1381 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Check for heat, smoke, odor or smoldering before disturbing piles, bales, sacks or containers.
- Avoid breaking apart hot material unless incident command has a controlled plan for exposure, extinguishment and overhaul.
- Isolate the area and remove ignition sources if it is safe to do so.
- Use thermal imaging, monitoring and extended overhaul where available.
- Use ERG Guide 136, shipping papers, SDS and local SOP for protective actions and fire-control decisions.
📋 Copy & Share Field Card
UN 1381 — Phosphorus, yellow, dry or under water oUse 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.