☣️ UN 1420 • CLASS 4
Potassium metal alloys, liquid
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 1420
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: Isolate spill area at least 50m in all directions; for fire, isolate 800m and consider evacuation for 1600m downwind
Chemical & Response Details
| Also known as | Potassium metal alloys in liquid formLiquid potassium alloysMolten potassium alloysK-metal alloys |
| Appearance | Silvery-white to gray molten metal alloy with a metallic luster. No odor. Liquid at ambient or elevated temperatures depending on alloy composition. |
| Flash Point | Not applicable (pyrophoric metal) |
| Boiling Point | Varies by alloy composition, typically above 760C (1400F) |
| Vapor Density | Not applicable (liquid metal) |
| Water Reactivity | Reacts violently and exothermically with water, releasing flammable hydrogen gas and heat; may ignite spontaneously on contact with moisture or humid air |
| Extinguishing | Dry sand, dry graphite powder, soda ash, or Met-L-X powder; absolutely no water, foam, CO2, or halogenated agents |
| PPE | ⚠️ Level A required for spill response; full face SCBA; chemical-resistant suit; face shield and heat-resistant gloves for fire; avoid all skin contact |
| Isolation | ERG 138: Isolate spill area at least 50m in all directions; for fire, isolate 800m and consider evacuation for 1600m downwind |
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 1420 — Potassium metal alloys, liquid HAZMAT RADIO NOTE — UN 1420
Product: Potassium metal alloys, liquid
Class 4 / Dangerous When Wet / ERG 138
PPE: Level A required for spill response; full face SCBA; chemical-resistant suit; face shield and heat-resistant gloves for fire; avoid all skin contact
ISOLATION: ERG 138: Isolate spill area at least 50m in all directions; for fire, isolate 800m and consider evacuation for 1600m 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 1420 — Potassium metal alloys, liquid
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Silvery-white to gray molten metal alloy with a metallic luster. No odor. Liquid at ambient or elevated temperatures depending on alloy composition.
Water Reactivity: Reacts violently and exothermically with water, releasing flammable hydrogen gas and heat; may ignite spontaneously on contact with moisture or humid air
Extinguishing: Dry sand, dry graphite powder, soda ash, or Met-L-X powder; absolutely no water, foam, CO2, or halogenated agents
PPE: Level A required for spill response; full face SCBA; chemical-resistant suit; face shield and heat-resistant gloves for fire; avoid all skin contact
Isolation: ERG 138: Isolate spill area at least 50m in all directions; for fire, isolate 800m and consider evacuation for 1600m downwind
— 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/1420 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1420 Potassium metal alloys, liquid Cls4 ERG138 | allfirefighter.com/hazmat/un/1420SMS / 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/1420
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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 face SCBA; chemical-resistant suit; face shield and heat-resistant gloves for fire; avoid all skin contact
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.