UN 2010 — Magnesium hydride
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2010 is Magnesium hydride, a dangerous-when-wet metal hydride assigned to ERG Guide 138. Water or moist air can release flammable hydrogen gas and heat.
Hazard overview: DANGEROUS WHEN WET metal hydride; contact with water or moist air produces flammable hydrogen gas. Reaction may generate heat and ignite spontaneously. May be ignited by heat, sparks or flames.
Response guidance: For a UN 2010 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 138. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff or dust spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2010 should emphasize moisture exclusion, dry-agent/Class D tactics where appropriate, hydrogen or ammonia gas generation, re-ignition and dust control. Use ERG 138, SDS and local SOP.
Regulatory context: Magnesium hydride is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Magnesium hydride should be stored dry in compatible sealed containers away from water, moisture, oxidizers, acids where incompatible, ignition sources and unauthorized access. Keep compatible dry extinguishing media available and prevent dust generation.
UN 2010 Quick Details
Common Hazards of UN 2010
- DANGEROUS WHEN WET metal hydride; contact with water or moist air produces flammable hydrogen gas.
- Reaction may generate heat and ignite spontaneously.
- May be ignited by heat, sparks or flames.
- Water, foam or CO2 may worsen reaction or spread fire.
- May re-ignite after apparent extinguishment.
- Dust or decomposition products may irritate eyes, skin and respiratory tissue.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
White to gray crystalline powder or solid. Odorless. Stable when dry but highly reactive with moisture.
| Also known as | Magnesium dihydrideMgH2Magnesium hydride powder |
| CAS Number | 7693-27-8 |
| Appearance | White to gray crystalline powder or solid. Odorless. Stable when dry but highly reactive with moisture. |
| Flash Point | Not applicable (water-reactive solid, pyrophoric when moist) |
| Boiling Point | Not applicable (decomposes above 280C/536F) |
| Vapor Density | Not applicable (solid material) |
| Water Reactivity | Reacts violently with water producing flammable hydrogen gas and heat; may ignite spontaneously |
Fireground Response Guidance — UN 2010
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for smoke, dust or fire exposure. Wear fire-resistant and chemical-resistant protection selected from SDS; avoid moisture contamination and dust generation.
Isolation & Evacuation
First Actions for a UN 2010 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid breathing dust, vapor, fumes, mist or smoke and avoid skin or eye contact.
- Keep water, foam and moisture away from the material unless incident command confirms a compatible control use.
- Do not touch damaged containers or spilled material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, water reaction, vapor generation, dust spread or unknown product identity.
- Use ERG Guide 138, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2010 — Magnesium hydrideUse 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.