☣️ UN 3404 • CLASS 4
Potassium sodium alloys, solid
Placard: Dangerous When Wet. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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 3404
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: Isolate spill/leak area immediately for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Evacuate immediate area if fire develops. Protect from moisture and precipitation.
Chemical & Response Details
| Also known as | NaK alloySodium-potassium alloyLiquid metal coolantNaK eutectic |
| CAS Number | 11135-81-2 |
| Appearance | Silvery-white metallic solid or liquid at room temperature depending on composition. Typical eutectic alloy (22% Na, 78% K) is liquid above -12.6°C. Lustrous appearance when fresh, tarnishes rapidly in air. |
| Flash Point | Not applicable (spontaneously ignites with water/moist air) |
| Boiling Point | 784°C (1443°F) for eutectic composition |
| Vapor Density | Not applicable (metal, negligible vapor pressure at ambient) |
| Water Reactivity | Reacts violently and explosively with water, producing flammable hydrogen gas and heat. May ignite spontaneously. Never use water for extinguishment or cleanup. |
| Extinguishing | Dry sand, dry salt (NaCl), dry graphite powder, Class D extinguishing powder (Met-L-X, Na-X). No water, no foam, no CO2, no halogenated agents. |
| PPE | ⚠️ Level A required for spill response. Full encapsulation, SCBA, chemical-resistant gloves and boots. Avoid all moisture contact. Handle only in inert atmosphere (argon/nitrogen) when possible. |
| Isolation | ERG 138: Isolate spill/leak area immediately for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Evacuate immediate area if fire develops. Protect from moisture and precipitation. |
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 3404 — Potassium sodium alloys, solid HAZMAT RADIO NOTE — UN 3404
Product: Potassium sodium alloys, solid
Class 4 / Dangerous When Wet / ERG 138
PPE: Level A required for spill response. Full encapsulation, SCBA, chemical-resistant gloves and boots. Avoid all moisture contact. Handle only in inert atmosphere (argon/nitrogen) when possible.
ISOLATION: ERG 138: Isolate spill/leak area immediately for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Evacuate immediate area if fire develops. Protect from moisture and precipitation.
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 3404 — Potassium sodium alloys, solid
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Silvery-white metallic solid or liquid at room temperature depending on composition. Typical eutectic alloy (22% Na, 78% K) is liquid above -12.6°C. Lustrous appearance when fresh, tarnishes rapidly in air.
Water Reactivity: Reacts violently and explosively with water, producing flammable hydrogen gas and heat. May ignite spontaneously. Never use water for extinguishment or cleanup.
Extinguishing: Dry sand, dry salt (NaCl), dry graphite powder, Class D extinguishing powder (Met-L-X, Na-X). No water, no foam, no CO2, no halogenated agents.
PPE: Level A required for spill response. Full encapsulation, SCBA, chemical-resistant gloves and boots. Avoid all moisture contact. Handle only in inert atmosphere (argon/nitrogen) when possible.
Isolation: ERG 138: Isolate spill/leak area immediately for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Evacuate immediate area if fire develops. Protect from moisture and precipitation.
— 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/3404 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3404 Potassium sodium alloys, solid Cls4 ERG138 | allfirefighter.com/hazmat/un/3404SMS / 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/3404
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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 A required for spill response. Full encapsulation, SCBA, chemical-resistant gloves and boots. Avoid all moisture contact. Handle only in inert atmosphere (argon/nitrogen) when possible.
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.