☣️ UN 3476 • CLASS 4
UN 3476 — Fuel cell cartridges contained in equipment, containing water-reactive substances
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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.
UN 3476 applies to fuel cell cartridges contained in equipment when the cartridges contain water-reactive substances.
Hazard overview: These cartridges can produce flammable gases on contact with water or moist air. Some contents may ignite or react violently if the cartridge is damaged.
Response guidance: Keep the equipment dry, isolate damaged cartridges, prevent water contact, and use dry chemical, dry sand, or soda ash only if fire control is needed.
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UN 3476 Quick Details
UN 3476
Product name: Fuel cell cartridges contained in equipment, containing water-reactive substances
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: isolate spill 25m all directions; if fire, evacuate 800m downwind; keep containers dry
Common Hazards of UN 3476
- 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.
Chemical Identity & Physical Properties
Fuel cell cartridges or containers integrated within equipment contain water-reactive substances that may be solid or liquid, with varying appearances depending on the specific material.
| Also known as | Fuel cell cartridges with water-reactive materialsEquipment-integrated fuel cell cartridgesWater-reactive fuel cell systems |
| Appearance | Sealed cartridges or containers integrated within equipment, containing water-reactive substances that may be solid or liquid. Appearance varies depending on the specific water-reactive material contained. |
| Flash Point | Not applicable (water-reactive material) |
| Boiling Point | Not applicable (varies by contained substance) |
| Vapor Density | Not applicable (contained system) |
| Water Reactivity | Reacts with water to produce flammable gases; may ignite spontaneously on contact with water or moist air; some formulations react violently or explosively |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3476
Extinguishing Media
Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2
PPE Requirements
⚠️ Level B minimum; SCBA required; chemical-resistant suit for spills; avoid moisture exposure during handling
Level B with SCBA and chemical-resistant clothing is recommended for damaged cartridges, leaking contents, fire, or confined-space response.
Isolation & Evacuation
ERG 138: isolate spill 25m all directions; if fire, evacuate 800m downwind; keep containers dry
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 3476 Incident
- CALL 911. Then call the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate the spill or leak area in all directions using ERG guidance for the material and package size.
- Consider initial downwind evacuation for at least 300 meters (1000 feet).
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📋 Copy & Share Field Card
UN 3476 — Fuel cell cartridges contained in equipmHAZMAT RADIO NOTE — UN 3476
Product: Fuel cell cartridges contained in equipment, containing water-reactive substances
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum; SCBA required; chemical-resistant suit for spills; avoid moisture exposure during handling
ISOLATION: ERG 138: isolate spill 25m all directions; if fire, evacuate 800m downwind; keep containers dry
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 3476 — Fuel cell cartridges contained in equipment, containing water-reactive substances
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Sealed cartridges or containers integrated within equipment, containing water-reactive substances that may be solid or liquid. Appearance varies depending on the specific water-reactive material contained.
Water Reactivity: Reacts with water to produce flammable gases; may ignite spontaneously on contact with water or moist air; some formulations react violently or explosively
Extinguishing: Dry chemical, dry sand, soda ash; DO NOT use water, foam, or CO2
PPE: Level B minimum; SCBA required; chemical-resistant suit for spills; avoid moisture exposure during handling
Isolation: ERG 138: isolate spill 25m all directions; if fire, evacuate 800m downwind; keep containers dry
— 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 the emergency response number on the shipping paper, if available.
• 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/fuel-cell-cartridges-contained-un-3476 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3476 Fuel cell cartridges contained in equipment, containing water-reactive substances Cls4 ERG138 | allfirefighter.com/hazmat/un/fuel-cell-cartridges-contained-un-3476SMS / 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/fuel-cell-cartridges-contained-un-3476
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Frequently Asked Questions about UN 3476
Yes. Flammable gas may be produced if the contents contact water or moisture.
Yes. Water or moist air can generate flammable gases and may cause ignition or violent reaction.
Level B with SCBA and chemical-resistant clothing is recommended for damaged or leaking units.
Keep containers dry, isolate the area, stay upwind, and do not use water, foam, or CO2 on reactive contents.
UN 3476 is assigned to ERG Guide 138 for initial emergency response guidance.
Yes. The spelling was corrected from waterreactive to water-reactive.
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.