☣️ UN 2950 • CLASS 4
Magnesium granules, coated
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.
Advertisement
Quick details
UN 2950
Class: 4
Placard type: Dangerous When Wet
ERG: Guide 138 (check current ERG)
Isolation: ERG 138: isolate spill 25m all directions; if tank/rail car involved in fire isolate 800m and consider evacuation 800m downwind
Chemical & Response Details
| Also known as | Magnesium metal granulesCoated magnesiumMagnesium granularMg granules |
| CAS Number | 7439-95-4 |
| Appearance | Silver-gray metallic granules with a protective coating to reduce reactivity. Solid at room temperature with minimal odor. |
| Flash Point | Not applicable (pyrophoric metal) |
| Boiling Point | 1090C (1994F) |
| Vapor Density | Not applicable (solid metal) |
| Water Reactivity | Reacts with water producing flammable hydrogen gas; coating reduces but does not eliminate reactivity; heat accelerates reaction |
| Extinguishing | Dry sand, soda ash, dry chemical (Class D powder preferred); DO NOT use water, foam, CO2, or halogenated agents |
| PPE | ⚠️ Minimum Level C with face shield; Level B with SCBA if fire or gas evolution present; heat-resistant gloves recommended |
| Isolation | ERG 138: isolate spill 25m all directions; if tank/rail car involved in fire isolate 800m and consider evacuation 800m 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).
Advertisement
📋 Copy & Share
UN 2950 — Magnesium granules, coated HAZMAT RADIO NOTE — UN 2950
Product: Magnesium granules, coated
Class 4 / Dangerous When Wet / ERG 138
PPE: Minimum Level C with face shield; Level B with SCBA if fire or gas evolution present; heat-resistant gloves recommended
ISOLATION: ERG 138: isolate spill 25m all directions; if tank/rail car involved in fire isolate 800m and consider evacuation 800m 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 2950 — Magnesium granules, coated
Class: 4 | Placard: Dangerous When Wet | ERG Guide: 138
Appearance: Silver-gray metallic granules with a protective coating to reduce reactivity. Solid at room temperature with minimal odor.
Water Reactivity: Reacts with water producing flammable hydrogen gas; coating reduces but does not eliminate reactivity; heat accelerates reaction
Extinguishing: Dry sand, soda ash, dry chemical (Class D powder preferred); DO NOT use water, foam, CO2, or halogenated agents
PPE: Minimum Level C with face shield; Level B with SCBA if fire or gas evolution present; heat-resistant gloves recommended
Isolation: ERG 138: isolate spill 25m all directions; if tank/rail car involved in fire isolate 800m and consider evacuation 800m 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/2950 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2950 Magnesium granules, coated Cls4 ERG138 | allfirefighter.com/hazmat/un/2950SMS / 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/2950
Advertisement
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.
Minimum Level C with face shield; Level B with SCBA if fire or gas evolution present; heat-resistant gloves recommended
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.