☣️ UN 3191 • CLASS 4
UN 3191 — Self-heating solid, poisonous, inorganic, n.o.s.
Placard: Spontaneously Combustible. ERG Guide 136. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ 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.
Self-heating solid, poisonous, inorganic, n.o.s. is a broad self-heating solid entry. Product identity, packaging and temperature history control the response.
Hazard overview: The main risk is spontaneous heat buildup leading to ignition, toxic smoke, re-ignition or container failure.
Response guidance: Isolate, keep away from combustibles and moisture, monitor for heating, and use dry media unless SDS approves another method.
Firefighter training notes: Use this page as initial reference only; responders should train from ERG, SDS, department SOPs and product-specific preplans.
Regulatory context: UN 3191 is regulated for transport under its proper shipping name, hazard class 4 and ERG Guide 136. Verify current DOT/PHMSA requirements and shipping papers.
Storage & handling: Store only as permitted by the SDS and applicable code: segregate from incompatible materials, protect packages from heat, damage and moisture, and maintain labels.
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UN 3191 Quick Details
UN 3191
Product name: Self-heating solid, poisonous, inorganic, n.o.s.
DOT Class: 4
Placard type: Spontaneously Combustible
ERG Guide: 136 (check current ERG)
Initial 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
Common Hazards of UN 3191
- Self-heating solid; may generate heat and ignite when exposed to air, moisture or contamination.
- Fire can develop without an outside ignition source if heat is not dissipated.
- Burning material may produce dense irritating, toxic or corrosive smoke.
- Water compatibility varies; water may worsen reaction or spread hot material.
- Containers may rupture when heated.
- Re-ignition is possible after apparent extinguishment.
- Because this is an n.o.s. entry, exact SDS data controls final tactics.
Chemical Identity & Physical Properties
Variable appearance depending on specific substance; typically a solid that may be transported in molten form. Capable of spontaneous heating when exposed to air.
| 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; avoid water or moisture until exact material compatibility is confirmed |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3191
Extinguishing Media
Dry chemical, dry sand, soda ash or other SDS-approved dry media; avoid water unless confirmed compatible
PPE Requirements
⚠️ Level B minimum; SCBA required; full protective clothing due to toxic inhalation hazard and rapid burning with irritating fumes
Use SCBA and chemical protective clothing; upgrade protection for toxic, corrosive or unknown vapor conditions.
Isolation & Evacuation
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
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 136).
First Actions for a UN 3191 Incident
- Call 911 and the emergency response number shown on shipping papers.
- Keep unauthorized personnel away and establish an isolation perimeter.
- Stay upwind, uphill and upstream; avoid low areas where vapors or gases may collect.
- Avoid breathing vapors, dust, smoke or decomposition products.
- Do not touch damaged containers or spilled material without appropriate PPE.
- Separate from combustibles, moisture and ignition sources while monitoring for heat buildup.
- Ventilate confined spaces only if trained, equipped and atmospheric monitoring supports entry.
- Use ERG guidance, SDS, labels and shipping papers to confirm the exact hazards before action.
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📋 Copy & Share Field Card
UN 3191 — Self-heating solid, poisonous, inorganicHAZMAT 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; avoid water or moisture until exact material compatibility is confirmed
Extinguishing: Dry chemical, dry sand, soda ash or other SDS-approved dry media; avoid water unless confirmed compatible
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 —
• Self-heating solid; may generate heat and ignite when exposed to air, moisture or contamination.
• Fire can develop without an outside ignition source if heat is not dissipated.
• Burning material may produce dense irritating, toxic or corrosive smoke.
— First Actions —
• Call 911 and the emergency response number shown on shipping papers.
• Keep unauthorized personnel away and establish an isolation perimeter.
• Stay upwind, uphill and upstream; avoid low areas where vapors or gases may collect.
• Avoid breathing vapors, dust, smoke or decomposition products.
SOURCE: allfirefighter.com/hazmat/un/self-heating-solid-poisonous-un-3191 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3191 Self-heating solid, poisonous, inorganic, n.o.s. Cls4 ERG136 | allfirefighter.com/hazmat/un/self-heating-solid-poisonous-un-3191SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/self-heating-solid-poisonous-un-3191
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Frequently Asked Questions about UN 3191
It is a broad toxic, organic, inorganic self-heating solid entry; the exact product must be confirmed.
Yes. Self-heating materials can reach ignition temperature without an external flame.
Do not use water unless the SDS confirms compatibility; dry agents are safer for unknown products.
Use SCBA with chemical protective clothing; Level A may be needed for toxic or corrosive vapors.
Heat can remain inside the material and flare again when exposed to air.
Smoke, vapor or contact may be toxic; avoid all exposure and contain contaminated runoff.
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.