☣️ UN 3400 • CLASS 4
UN 3400 — Organometallic substance, solid, self-heating
Placard: Spontaneously Combustible. ERG Guide 138. 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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UN 3400 Quick Details
UN 3400
Product name: Organometallic substance, solid, self-heating
DOT Class: 4
Placard type: Spontaneously Combustible
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: Initial isolation 100m in all directions. Protect from water and moisture. If fire involves this material, isolate 800m and consider evacuation for 1600m downwind.
Common Hazards of UN 3400
- Produce flammable gases on contact with water.
- May ignite on contact with water or moist air.
- Some react vigorously or explosively on contact with water.
- May be ignited by heat, sparks or flames.
- May re-ignite after fire is extinguished.
- Some are transported in highly flammable liquids.
- Runoff may create fire or explosion hazard.
- Inhalation or contact with vapors, substance or decomposition products may cause severe injury or
Chemical Identity & Physical Properties
| Also known as | Organometallic compound solidSelf-heating organometallic materialPyrophoric organometallic solidMetal-organic compound self-heating |
| Appearance | Solid material, color varies by specific compound. May be powder, granules, or crystalline. Often pyrophoric with potential for spontaneous ignition in air or upon contact with moisture. |
| Flash Point | Not applicable (pyrophoric solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts vigorously to violently with water producing flammable gases. May ignite spontaneously on contact with water or moist air. Do not use water for firefighting. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3400
Extinguishing Media
Dry sand, dry chemical, soda ash. DO NOT use water, foam, CO2, or halogenated agents.
PPE Requirements
⚠️ Level A required for spill response. SCBA mandatory. Chemical-resistant suit with butyl rubber gloves. Avoid all sources of ignition and moisture.
Isolation & Evacuation
ERG 138: Initial isolation 100m in all directions. Protect from water and moisture. If fire involves this material, isolate 800m and consider evacuation for 1600m downwind.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 3400 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- Consider initial downwind evacuation for at least 300 meters (1000 feet).
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UN 3400 — Organometallic substance, solid, self-heHAZMAT RADIO NOTE — UN 3400
Product: Organometallic substance, solid, self-heating
Class 4 / Spontaneously Combustible / ERG 138
PPE: Level A required for spill response. SCBA mandatory. Chemical-resistant suit with butyl rubber gloves. Avoid all sources of ignition and moisture.
ISOLATION: ERG 138: Initial isolation 100m in all directions. Protect from water and moisture. If fire involves this material, isolate 800m and consider evacuation for 1600m downwind.
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 3400 — Organometallic substance, solid, self-heating
Class: 4 | Placard: Spontaneously Combustible | ERG Guide: 138
Appearance: Solid material, color varies by specific compound. May be powder, granules, or crystalline. Often pyrophoric with potential for spontaneous ignition in air or upon contact with moisture.
Water Reactivity: Reacts vigorously to violently with water producing flammable gases. May ignite spontaneously on contact with water or moist air. Do not use water for firefighting.
Extinguishing: Dry sand, dry chemical, soda ash. DO NOT use water, foam, CO2, or halogenated agents.
PPE: Level A required for spill response. SCBA mandatory. Chemical-resistant suit with butyl rubber gloves. Avoid all sources of ignition and moisture.
Isolation: ERG 138: Initial isolation 100m in all directions. Protect from water and moisture. If fire involves this material, isolate 800m and consider evacuation for 1600m downwind.
— Key Hazards —
• Produce flammable gases on contact with water.
• May ignite on contact with water or moist air.
• Some react vigorously or explosively on contact with water.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/3400 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3400 Organometallic substance, solid, self-heating Cls4 ERG138 | allfirefighter.com/hazmat/un/3400SMS / 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/3400
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Frequently Asked Questions about UN 3400
Produce flammable gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Runoff may create fire or explosion hazard. Inhalation or contact with vapors, substance or decomposition products may cause severe injury or
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A required for spill response. SCBA mandatory. Chemical-resistant suit with butyl rubber gloves. Avoid all sources of ignition and moisture.
Water reactivity: Reacts vigorously to violently with water producing flammable gases. May ignite spontaneously on contact with water or moist air. Do not use water for firefighting.. Recommended extinguishing: Dry sand, dry chemical, soda ash. DO NOT use water, foam, CO2, or halogenated agents..
ERG Guide 138 recommendation: ERG 138: Initial isolation 100m in all directions. Protect from water and moisture. If fire involves this material, isolate 800m and consider evacuation for 1600m downwind.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 138 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.