UN 2950 — Magnesium granules, coated
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2950 is Magnesium granules, coated, a dangerous-when-wet magnesium metal entry assigned to ERG Guide 138. Moisture can release hydrogen and cause ignition.
Hazard overview: DANGEROUS WHEN WET coated magnesium granules; water or moisture can release flammable hydrogen gas. Coating reduces but does not eliminate reactivity, especially if damaged, hot or finely divided. May ignite from heat, sparks, friction or moisture and burn with intense heat.
Response guidance: For UN 2950, isolate the area, avoid dust/friction and use SCBA. Use only compatible dry media, watch for re-ignition or violent decomposition and follow SDS/ERG 138.
Firefighter training notes: Training for UN 2950 should emphasize dry-media tactics, moisture/friction control, re-ignition, remote operations, SCBA use and runoff/debris control. Use ERG 138, SDS and local SOP.
Regulatory context: Magnesium granules, coated is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Magnesium granules, coated should be stored dry in tightly closed compatible containers away from moisture, heat, ignition sources and incompatible materials. Keep compatible dry media available.
UN 2950 Quick Details
Common Hazards of UN 2950
- DANGEROUS WHEN WET coated magnesium granules; water or moisture can release flammable hydrogen gas.
- Coating reduces but does not eliminate reactivity, especially if damaged, hot or finely divided.
- May ignite from heat, sparks, friction or moisture and burn with intense heat.
- Water, foam, CO2 and halogenated agents can worsen burning metal reactions.
- May re-ignite after apparent extinguishment.
- Runoff may create fire, explosion and caustic contamination hazards.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Silver-gray metallic granules with a protective coating to reduce reactivity. Solid at room temperature with minimal odor.
| 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 |
Fireground Response Guidance — UN 2950
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for fire, dust or smoke. Wear flame/chemical protection and avoid dust, friction and incompatible media.
Isolation & Evacuation
First Actions for a UN 2950 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, gas, mist, smoke or fumes and avoid skin or eye contact.
- Keep water or moisture contact controlled because reaction, toxic fuming or re-ignition hazards may be severe.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated liquid, dust, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 138, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2950 — Magnesium granules, coatedUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.