☣️ UN 3396 • CLASS 4
Organometallic substance, solid, water-reactive, flammable
Placard: Dangerous When Wet. 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 3396
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: Isolate spill area immediate 25m (80ft) all directions; if tank/rail car involved in fire isolate 800m (0.5 miles) all directions and consider initial evacuation 800m
Chemical & Response Details
| Also known as | Organometallic compoundsMetal-organic solidsWater-reactive organometallic materialsPyrophoric organometallic substances |
| Appearance | Solid materials varying in color from white to gray or metallic appearance, typically odorless or with slight metallic odor. Physical state is solid at room temperature and may be powdered, crystalline, or in chunk form. |
| Flash Point | Not applicable (spontaneously combustible on contact with water or moist air) |
| Boiling Point | Variable depending on specific compound; most decompose before boiling |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts violently with water producing flammable gases (often hydrogen or metal hydrides); may ignite spontaneously. DO NOT USE WATER. |
| Extinguishing | Dry chemical (Class D for metal fires), dry sand, dry graphite powder, soda ash; absolutely NO water or aqueous agents |
| PPE | ⚠️ Level B minimum with SCBA required; chemical-resistant suit; face shield; keep upwind; avoid all moisture contact including perspiration |
| Isolation | ERG 138: Isolate spill area immediate 25m (80ft) all directions; if tank/rail car involved in fire isolate 800m (0.5 miles) all directions and consider initial evacuation 800m |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- 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
First actions (field-minded)
- 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 3396 — Organometallic substance, solid, water-r HAZMAT RADIO NOTE — UN 3396
Product: Organometallic substance, solid, water-reactive, flammable
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required; chemical-resistant suit; face shield; keep upwind; avoid all moisture contact including perspiration
ISOLATION: ERG 138: Isolate spill area immediate 25m (80ft) all directions; if tank/rail car involved in fire isolate 800m (0.5 miles) all directions and consider initial evacuation 800m
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 3396 — Organometallic substance, solid, water-reactive, flammable
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Solid materials varying in color from white to gray or metallic appearance, typically odorless or with slight metallic odor. Physical state is solid at room temperature and may be powdered, crystalline, or in chunk form.
Water Reactivity: Reacts violently with water producing flammable gases (often hydrogen or metal hydrides); may ignite spontaneously. DO NOT USE WATER.
Extinguishing: Dry chemical (Class D for metal fires), dry sand, dry graphite powder, soda ash; absolutely NO water or aqueous agents
PPE: Level B minimum with SCBA required; chemical-resistant suit; face shield; keep upwind; avoid all moisture contact including perspiration
Isolation: ERG 138: Isolate spill area immediate 25m (80ft) all directions; if tank/rail car involved in fire isolate 800m (0.5 miles) all directions and consider initial evacuation 800m
— 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/3396 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3396 Organometallic substance, solid, water-reactive, flammable Cls4 ERG138 | allfirefighter.com/hazmat/un/3396SMS / 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/3396
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FAQ
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 B minimum with SCBA required; chemical-resistant suit; face shield; keep upwind; avoid all moisture contact including perspiration
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.