☣️ UN 3191 • CLASS 4
Self-heating solid, poisonous, inorganic, n.o.s.
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 3191
Class: 4
Placard type: Spontaneously Combustible
ERG: Guide 136 (check current ERG)
Isolation: ERG 136: isolate spill or leak area immediately for at least 25-50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters in all directions
Chemical & Response Details
| Also known as | Self-heating solid, toxic, inorganic, n.o.s.Self-heating solid, poisonous, inorganic, not otherwise specifiedUN3191 |
| Appearance | Variable appearance depending on specific substance; typically a solid that may be transported in molten form. Capable of spontaneous heating when exposed to air. |
| Flash Point | Not applicable (self-heating solid) |
| Boiling Point | Variable depending on specific substance; may be transported molten |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Variable; use caution as some inorganic self-heating materials may react with water |
| Extinguishing | Dry chemical, sand, dry earth; avoid water-based agents initially |
| PPE | ⚠️ Level B minimum; SCBA required; full protective clothing due to toxic inhalation hazard and rapid burning with irritating fumes |
| Isolation | ERG 136: isolate spill or leak area immediately for at least 25-50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters 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 3191 — Self-heating solid, poisonous, inorganic HAZMAT RADIO NOTE — UN 3191
Product: Self-heating solid, poisonous, inorganic, n.o.s.
Class 4 / Spontaneously Combustible / ERG 136
PPE: Level B minimum; SCBA required; full protective clothing due to toxic inhalation hazard and rapid burning with irritating fumes
ISOLATION: ERG 136: isolate spill or leak area immediately for at least 25-50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters 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 3191 — Self-heating solid, poisonous, inorganic, n.o.s.
Class: 4 | Placard: Spontaneously Combustible | ERG Guide: 136
Appearance: Variable appearance depending on specific substance; typically a solid that may be transported in molten form. Capable of spontaneous heating when exposed to air.
Water Reactivity: Variable; use caution as some inorganic self-heating materials may react with water
Extinguishing: Dry chemical, sand, dry earth; avoid water-based agents initially
PPE: Level B minimum; SCBA required; full protective clothing due to toxic inhalation hazard and rapid burning with irritating fumes
Isolation: ERG 136: isolate spill or leak area immediately for at least 25-50 meters in all directions; if tank/rail car involved in fire, isolate 800 meters 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/3191 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3191 Self-heating solid, poisonous, inorganic, n.o.s. Cls4 ERG136 | allfirefighter.com/hazmat/un/3191SMS / 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/3191
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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 B minimum; SCBA required; full protective clothing due to toxic inhalation hazard and rapid burning with irritating fumes
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.