☣️ UN 3124 • CLASS 6
Poisonous solid, self-heating, n.o.s.
Placard: Toxic. 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 3124
Class: 6
Placard type: Toxic
ERG: Guide 136 (check current ERG)
Isolation: ERG 136: isolate spill area minimum 25m all directions; if fire or large spill, isolate 800m in all directions and consider evacuation
Chemical & Response Details
| Also known as | Toxic solid, self-heating, not otherwise specifiedSelf-heating poisonous solidSelf-heating toxic solid N.O.S. |
| Appearance | Variable appearance depending on specific substance; typically a solid material that can spontaneously heat and ignite when exposed to air. May be transported in molten form at elevated temperatures. |
| Flash Point | Not applicable (self-heating material, spontaneous ignition hazard) |
| Boiling Point | Variable depending on specific substance |
| Vapor Density | Variable depending on specific substance |
| Water Reactivity | Variable depending on specific substance; avoid water unless material is confirmed compatible |
| Extinguishing | Dry chemical, dry sand, soda ash; no water unless specifically approved for material |
| PPE | ⚠️ Level A or B required; SCBA mandatory; full chemical protective suit; material is both toxic and self-heating |
| Isolation | ERG 136: isolate spill area minimum 25m all directions; if fire or large spill, isolate 800m in all directions and consider evacuation |
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 3124 — Poisonous solid, self-heating, n.o.s. HAZMAT RADIO NOTE — UN 3124
Product: Poisonous solid, self-heating, n.o.s.
Class 6 / Toxic / ERG 136
PPE: Level A or B required; SCBA mandatory; full chemical protective suit; material is both toxic and self-heating
ISOLATION: ERG 136: isolate spill area minimum 25m all directions; if fire or large spill, isolate 800m in all directions and consider evacuation
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 3124 — Poisonous solid, self-heating, n.o.s.
Class: 6 | Placard: Toxic | ERG Guide: 136
Appearance: Variable appearance depending on specific substance; typically a solid material that can spontaneously heat and ignite when exposed to air. May be transported in molten form at elevated temperatures.
Water Reactivity: Variable depending on specific substance; avoid water unless material is confirmed compatible
Extinguishing: Dry chemical, dry sand, soda ash; no water unless specifically approved for material
PPE: Level A or B required; SCBA mandatory; full chemical protective suit; material is both toxic and self-heating
Isolation: ERG 136: isolate spill area minimum 25m all directions; if fire or large spill, isolate 800m in all directions and consider evacuation
— 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/3124 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3124 Poisonous solid, self-heating, n.o.s. Cls6 ERG136 | allfirefighter.com/hazmat/un/3124SMS / 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/3124
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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 or B required; SCBA mandatory; full chemical protective suit; material is both toxic and self-heating
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.