☣️ UN 3401 • CLASS 4
UN 3401 — Alkali metal amalgam, solid
Placard: Dangerous When Wet. 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 3401 Quick Details
UN 3401
Product name: Alkali metal amalgam, solid
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: Isolate spill area immediately for at least 50 meters in all directions. Evacuate 800 meters downwind if fire develops. Keep unauthorized personnel away.
Common Hazards of UN 3401
- 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 | Sodium amalgamPotassium amalgamLithium amalgamMercury-alkali metal alloy |
| Appearance | Silvery-white to gray metallic solid or semi-solid material. Odorless. Amalgam is an alloy of mercury with sodium, potassium, lithium, or other alkali metals in solid form at room temperature. |
| Flash Point | Not applicable (water-reactive solid, produces flammable hydrogen gas) |
| Boiling Point | Not applicable (decomposes on heating) |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts vigorously to violently with water, producing flammable hydrogen gas and heat. May ignite spontaneously on contact with moist air or water. Do not use water. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3401
Extinguishing Media
Dry sand, dry chemical, soda ash, or dry graphite powder. DO NOT use water, foam, CO2, or halogenated agents.
PPE Requirements
⚠️ Level B minimum with SCBA required. Full chemical-resistant suit for spill response. Avoid any moisture contact. Work in dry, well-ventilated area.
Isolation & Evacuation
ERG 138: Isolate spill area immediately for at least 50 meters in all directions. Evacuate 800 meters downwind if fire develops. Keep unauthorized personnel away.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 3401 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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📋 Copy & Share Field Card
UN 3401 — Alkali metal amalgam, solidHAZMAT RADIO NOTE — UN 3401
Product: Alkali metal amalgam, solid
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA required. Full chemical-resistant suit for spill response. Avoid any moisture contact. Work in dry, well-ventilated area.
ISOLATION: ERG 138: Isolate spill area immediately for at least 50 meters in all directions. Evacuate 800 meters downwind if fire develops. Keep unauthorized personnel away.
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 3401 — Alkali metal amalgam, solid
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Silvery-white to gray metallic solid or semi-solid material. Odorless. Amalgam is an alloy of mercury with sodium, potassium, lithium, or other alkali metals in solid form at room temperature.
Water Reactivity: Reacts vigorously to violently with water, producing flammable hydrogen gas and heat. May ignite spontaneously on contact with moist air or water. Do not use water.
Extinguishing: Dry sand, dry chemical, soda ash, or dry graphite powder. DO NOT use water, foam, CO2, or halogenated agents.
PPE: Level B minimum with SCBA required. Full chemical-resistant suit for spill response. Avoid any moisture contact. Work in dry, well-ventilated area.
Isolation: ERG 138: Isolate spill area immediately for at least 50 meters in all directions. Evacuate 800 meters downwind if fire develops. Keep unauthorized personnel away.
— 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/3401 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3401 Alkali metal amalgam, solid Cls4 ERG138 | allfirefighter.com/hazmat/un/3401SMS / 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/3401
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Frequently Asked Questions about UN 3401
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. Full chemical-resistant suit for spill response. Avoid any moisture contact. Work in dry, well-ventilated area.
Water reactivity: Reacts vigorously to violently with water, producing flammable hydrogen gas and heat. May ignite spontaneously on contact with moist air or water. Do not use water.. Recommended extinguishing: Dry sand, dry chemical, soda ash, or dry graphite powder. DO NOT use water, foam, CO2, or halogenated agents..
ERG Guide 138 recommendation: ERG 138: Isolate spill area immediately for at least 50 meters in all directions. Evacuate 800 meters downwind if fire develops. Keep unauthorized personnel away.
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.