☣️ UN 1381 • CLASS 4
Phosphorus, yellow, dry or under water or in solution
Placard: Spontaneously Combustible. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 1381
Class: 4
Placard type: Spontaneously Combustible
ERG: Guide 136 (check current ERG)
Isolation: ERG 136: Isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m and consider evacuation 1600m in all directions
Chemical & Response Details
| 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 |
| Extinguishing | Dry sand, soda ash, or special dry chemical. DO NOT use water, foam, or CO2 on burning phosphorus. Water may be used to keep containers cool. |
| PPE | ⚠️ Level A required for large spills or fire conditions; SCBA mandatory; full chemical-resistant suit; prevent any skin contact as burns are severe and deep |
| Isolation | ERG 136: Isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m and consider evacuation 1600m in all directions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Extremely flammable; will ignite itself if exposed to air.
- Burns rapidly, releasing dense, white, irritating fumes.
- Substance may be transported in a molten form.
- May re-ignite after fire is extinguished.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated.
- Fire will produce irritating, corrosive and/or toxic gases.
- TOXIC and/or CORROSIVE; ingestion of substance or inhalation of decomposition products will cause
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Stay upwind, uphill and/or upstream.
- Keep unauthorized personnel away.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 1381 — Phosphorus, yellow, dry or under water o HAZMAT RADIO NOTE — UN 1381
Product: Phosphorus, yellow, dry or under water or in solution
Class 4 / Spontaneously Combustible / ERG 136
PPE: Level A required for large spills or fire conditions; SCBA mandatory; full chemical-resistant suit; prevent any skin contact as burns are severe and deep
ISOLATION: ERG 136: Isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m and consider evacuation 1600m in all directions
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 1381 — Phosphorus, yellow, dry or under water or in solution
Class: 4 | Placard: Spontaneously Combustible | ERG Guide: 136
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.
Water Reactivity: No significant reaction with water; typically stored under water to prevent air exposure and spontaneous ignition
Extinguishing: Dry sand, soda ash, or special dry chemical. DO NOT use water, foam, or CO2 on burning phosphorus. Water may be used to keep containers cool.
PPE: Level A required for large spills or fire conditions; SCBA mandatory; full chemical-resistant suit; prevent any skin contact as burns are severe and deep
Isolation: ERG 136: Isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m and consider evacuation 1600m in all directions
— Key Hazards —
• Extremely flammable; will ignite itself if exposed to air.
• Burns rapidly, releasing dense, white, irritating fumes.
• Substance may be transported in a molten form.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Stay upwind, uphill and/or upstream.
• Keep unauthorized personnel away.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/1381 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1381 Phosphorus, yellow, dry or under water or in solution Cls4 ERG136 | allfirefighter.com/hazmat/un/1381SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/1381
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FAQ
Extremely flammable; will ignite itself if exposed to air. Burns rapidly, releasing dense, white, irritating fumes. Substance may be transported in a molten form. May re-ignite after fire is extinguished. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. Fire will produce irritating, corrosive and/or toxic gases. TOXIC and/or CORROSIVE; ingestion of substance or inhalation of decomposition products will cause
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Stay upwind, uphill and/or upstream. Keep unauthorized personnel away.
Level A required for large spills or fire conditions; SCBA mandatory; full chemical-resistant suit; prevent any skin contact as burns are severe and deep
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 136 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.