☣️ UN 3391 • CLASS 4
Organometallic substance, solid, pyrophoric
Placard: Spontaneously Combustible. 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 3391
Class: 4
Placard type: Spontaneously Combustible
ERG: Guide 135 (check current ERG)
Isolation: ERG 135: Isolate spill 25m all directions. Large spill: initial isolation 100m, protective action 300m downwind.
Chemical & Response Details
| Also known as | Pyrophoric organometallic solidOrganometallic compound solid pyrophoricMetal-organic pyrophoric solid |
| Appearance | Solid material of varying color depending on specific compound. May appear as powder, granules, or crystalline solid. Ignites spontaneously when exposed to air at room temperature. |
| Flash Point | Not applicable (ignites spontaneously in air) |
| Boiling Point | Varies by specific compound |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts with moisture, may ignite or produce flammable gases. Keep completely dry. |
| Extinguishing | Dry sand, dry chemical, soda ash. NO water, NO foam, NO CO2 |
| PPE | ⚠️ Level A or B with SCBA required. Full body protection against pyrophoric fire. Heat-resistant gloves essential. |
| Isolation | ERG 135: Isolate spill 25m all directions. Large spill: initial isolation 100m, protective action 300m downwind. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Flammable/combustible material.
- May ignite on contact with moist air or moisture.
- May burn rapidly with flare-burning effect.
- Some react vigorously or explosively on contact with water.
- Some may decompose explosively when heated or involved in a fire.
- May re-ignite after fire is extinguished.
- Runoff may create fire or explosion hazard.
- Containers may explode when heated.
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 3391 — Organometallic substance, solid, pyropho HAZMAT RADIO NOTE — UN 3391
Product: Organometallic substance, solid, pyrophoric
Class 4 / Spontaneously Combustible / ERG 135
PPE: Level A or B with SCBA required. Full body protection against pyrophoric fire. Heat-resistant gloves essential.
ISOLATION: ERG 135: Isolate spill 25m all directions. Large spill: initial isolation 100m, protective action 300m 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 3391 — Organometallic substance, solid, pyrophoric
Class: 4 | Placard: Spontaneously Combustible | ERG Guide: 135
Appearance: Solid material of varying color depending on specific compound. May appear as powder, granules, or crystalline solid. Ignites spontaneously when exposed to air at room temperature.
Water Reactivity: Reacts with moisture, may ignite or produce flammable gases. Keep completely dry.
Extinguishing: Dry sand, dry chemical, soda ash. NO water, NO foam, NO CO2
PPE: Level A or B with SCBA required. Full body protection against pyrophoric fire. Heat-resistant gloves essential.
Isolation: ERG 135: Isolate spill 25m all directions. Large spill: initial isolation 100m, protective action 300m downwind.
— Key Hazards —
• Flammable/combustible material.
• May ignite on contact with moist air or moisture.
• May burn rapidly with flare-burning effect.
— 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/3391 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3391 Organometallic substance, solid, pyrophoric Cls4 ERG135 | allfirefighter.com/hazmat/un/3391SMS / 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/3391
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FAQ
Flammable/combustible material. May ignite on contact with moist air or moisture. May burn rapidly with flare-burning effect. Some react vigorously or explosively on contact with water. Some may decompose explosively when heated or involved in a fire. May re-ignite after fire is extinguished. Runoff may create fire or explosion hazard. Containers may explode when heated.
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 with SCBA required. Full body protection against pyrophoric fire. Heat-resistant gloves essential.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 135 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.