☣️ UN 1389 • CLASS 4
UN 1389 — Alkali metal amalgam, liquid
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.
Alkali metal amalgam is a silvery liquid metal alloy consisting of mercury combined with alkali metals (sodium, potassium, etc.). It is a hazardous material that requires special handling and emergency response.
Hazard overview: Alkali metal amalgam produces flammable gases on contact with water and may ignite on contact with water or moist air.
Response guidance: In the event of a fire or water contact, use dry sand, dry chemical, or soda ash to extinguish. Do not use water, foam, or CO2.
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UN 1389 Quick Details
UN 1389
Product name: Alkali metal amalgam, liquid
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: isolate spill area minimum 25m all directions. If fire or water contact, isolate 800m and consider evacuation 1600m downwind.
Common Hazards of UN 1389
- 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
Alkali metal amalgam is a dense, mobile liquid at room temperature with a metallic luster.
| Also known as | Sodium amalgam liquidPotassium amalgam liquidMercury-alkali metal alloyLiquid metal amalgam |
| Appearance | Silvery liquid metal alloy consisting of mercury combined with alkali metals (sodium, potassium, etc.). Dense, mobile liquid at room temperature with metallic luster. |
| Flash Point | Not applicable (reactive metal) |
| Boiling Point | Varies by composition, mercury component boils at 357C (675F) |
| Vapor Density | Not applicable (liquid metal, mercury vapor heavier than air) |
| Water Reactivity | Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously. Keep away from moisture and water. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1389
Extinguishing Media
Dry sand, dry chemical, soda ash. DO NOT use water, foam, or CO2. Use dry graphite powder or approved Class D extinguishing agents.
PPE Requirements
⚠️ Level A or B required; SCBA mandatory. Full chemical-resistant suit, neoprene or butyl rubber gloves. Protect against mercury vapor exposure.
Level A or B protective clothing, SCBA, full chemical-resistant suit, neoprene or butyl rubber gloves are required to handle alkali metal amalgam.
Isolation & Evacuation
ERG 138: isolate spill area minimum 25m all directions. If fire or water contact, isolate 800m and consider evacuation 1600m downwind.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 1389 Incident
- 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 1389 — Alkali metal amalgam, liquidHAZMAT RADIO NOTE — UN 1389
Product: Alkali metal amalgam, liquid
Class 4 / Dangerous When Wet / ERG 138
PPE: Level A or B required; SCBA mandatory. Full chemical-resistant suit, neoprene or butyl rubber gloves. Protect against mercury vapor exposure.
ISOLATION: ERG 138: isolate spill area minimum 25m all directions. If fire or water contact, isolate 800m and consider evacuation 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 1389 — Alkali metal amalgam, liquid
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Silvery liquid metal alloy consisting of mercury combined with alkali metals (sodium, potassium, etc.). Dense, mobile liquid at room temperature with metallic luster.
Water Reactivity: Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously. Keep away from moisture and water.
Extinguishing: Dry sand, dry chemical, soda ash. DO NOT use water, foam, or CO2. Use dry graphite powder or approved Class D extinguishing agents.
PPE: Level A or B required; SCBA mandatory. Full chemical-resistant suit, neoprene or butyl rubber gloves. Protect against mercury vapor exposure.
Isolation: ERG 138: isolate spill area minimum 25m all directions. If fire or water contact, isolate 800m and consider evacuation 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 —
• 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
SOURCE: allfirefighter.com/hazmat/un/alkali-metal-amalgam-liquid-un-1389 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1389 Alkali metal amalgam, liquid Cls4 ERG138 | allfirefighter.com/hazmat/un/alkali-metal-amalgam-liquid-un-1389SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/alkali-metal-amalgam-liquid-un-1389
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Frequently Asked Questions about UN 1389
Yes, alkali metal amalgam reacts violently with water producing flammable hydrogen gas and heat.
Yes, alkali metal amalgam may ignite on contact with water or moist air.
Dry sand, dry chemical, or soda ash can be used to extinguish alkali metal amalgam.
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.