☣️ UN 1418 • CLASS 4
UN 1418 — Magnesium alloys powder
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.
Magnesium alloys powder is a highly reactive substance that can ignite spontaneously on contact with water or moist air. It is essential to handle this material with extreme caution.
Hazard overview: Magnesium alloys powder can produce flammable gases on contact with water, which may lead to fires or explosions. It may also ignite on contact with moist air.
Response guidance: In case of a spill, isolate the area at least 25m in all directions. For large fires, evacuate 800m in all directions and do not use water.
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UN 1418 Quick Details
UN 1418
Product name: Magnesium alloys powder
DOT Class: 4
Placard type: Dangerous When Wet
ERG Guide: 138 (check current ERG)
Initial isolation: ERG 138: isolate spill area at least 25m in all directions; for large fires evacuate 800m in all directions; do not use water
Common Hazards of UN 1418
- 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
Magnesium alloys powder is a gray to silver-gray metallic powder with no odor. It may contain various alloying elements such as aluminum, zinc, or manganese.
| Also known as | Magnesium alloy dustMagnesium metal powder alloysMg alloy powder |
| Appearance | Gray to silver-gray metallic powder with no odor. Dry powder at room temperature, may contain various alloying elements such as aluminum, zinc, or manganese. |
| Flash Point | Not applicable (pyrophoric metal powder) |
| Boiling Point | Not applicable (metal alloy) |
| Vapor Density | Not applicable (solid metal powder) |
| Water Reactivity | Reacts with water to produce flammable hydrogen gas and heat; may ignite spontaneously on contact with water or moist air |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1418
Extinguishing Media
Dry sand, dry graphite powder, soda ash, Class D metal fire extinguisher; DO NOT use water, foam, CO2, or halogenated agents
PPE Requirements
⚠️ Level B minimum with SCBA; chemical-resistant gloves and apron; full face shield; avoid moisture and humid conditions during handling
Level B minimum with SCBA, chemical-resistant gloves and apron, full face shield, and avoid moisture and humid conditions during handling.
Isolation & Evacuation
ERG 138: isolate spill area at least 25m in all directions; for large fires evacuate 800m in all directions; do not use water
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 138).
First Actions for a UN 1418 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 1418 — Magnesium alloys powderHAZMAT RADIO NOTE — UN 1418
Product: Magnesium alloys powder
Class 4 / Dangerous When Wet / ERG 138
PPE: Level B minimum with SCBA; chemical-resistant gloves and apron; full face shield; avoid moisture and humid conditions during handling
ISOLATION: ERG 138: isolate spill area at least 25m in all directions; for large fires evacuate 800m in all directions; do not use water
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 1418 — Magnesium alloys powder
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Gray to silver-gray metallic powder with no odor. Dry powder at room temperature, may contain various alloying elements such as aluminum, zinc, or manganese.
Water Reactivity: Reacts with water to produce flammable hydrogen gas and heat; may ignite spontaneously on contact with water or moist air
Extinguishing: Dry sand, dry graphite powder, soda ash, Class D metal fire extinguisher; DO NOT use water, foam, CO2, or halogenated agents
PPE: Level B minimum with SCBA; chemical-resistant gloves and apron; full face shield; avoid moisture and humid conditions during handling
Isolation: ERG 138: isolate spill area at least 25m in all directions; for large fires evacuate 800m in all directions; do not use water
— 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/1418 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN1418 Magnesium alloys powder Cls4 ERG138 | allfirefighter.com/hazmat/un/1418SMS / 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/magnesium-alloys-powder-un-1418
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Frequently Asked Questions about UN 1418
Yes, UN 1418 can produce flammable gases on contact with water.
Avoid moisture and humid conditions during handling.
No, do not use water, foam, CO2, or halogenated agents.
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.