UN 3468 — Hydrogen in a metal hydride storage system contained in equipment
Placard: Flammable Gas. ERG Guide 115. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3468 is Hydrogen in a metal hydride storage system contained in equipment, a flammable gas-in-equipment entry assigned to ERG Guide 115. Hydrogen release, overhead accumulation and ignition are key hazards.
Hazard overview: EXTREMELY FLAMMABLE hydrogen stored in a metal hydride system; release can form explosive mixtures with air. Hydrogen is much lighter than air and may accumulate under roofs, hoods or poorly ventilated overhead spaces. Equipment damage, heating or depressurization can release gas from the hydride matrix.
Response guidance: For UN 3468, eliminate ignition sources, ventilate overhead spaces and cool exposed equipment. Do not extinguish a leak flame unless gas flow can be stopped safely.
Firefighter training notes: Training for UN 3468 should emphasize hydrogen flame behavior, overhead accumulation, gas monitoring, equipment cooling, source control and re-ignition prevention. Use ERG 115 and local SOP.
Regulatory context: Hydrogen in a metal hydride storage system contained in equipment is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, concentration, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Hydrogen in a metal hydride storage system contained in equipment should be stored away from heat, ignition sources and mechanical damage, with ventilation, leak detection and manufacturer guidance for metal hydride modules.
UN 3468 Quick Details
Common Hazards of UN 3468
- EXTREMELY FLAMMABLE hydrogen stored in a metal hydride system; release can form explosive mixtures with air.
- Hydrogen is much lighter than air and may accumulate under roofs, hoods or poorly ventilated overhead spaces.
- Equipment damage, heating or depressurization can release gas from the hydride matrix.
- Ignition may be invisible or hard to see in daylight; flashback can occur to the leak source.
- Pressure vessels or equipment may rupture when heated.
- Metal hydride material may remain hot or reactive after gas release.
- Fire may involve plastics, metals and equipment components in addition to hydrogen.
Chemical Identity & Physical Properties
Colorless, odorless, tasteless gas at room temperature. Lighter than air. Stored in metal hydride matrix which releases hydrogen gas when heated or depressurized.
| Also known as | Hydrogen gasDihydrogenMolecular hydrogenH2 |
| CAS Number | 1333-74-0 |
| Appearance | Colorless, odorless, tasteless gas at room temperature. Lighter than air. Stored in metal hydride matrix which releases hydrogen gas when heated or depressurized. |
| Flash Point | Not applicable (gas) |
| Boiling Point | -253C (-423F) |
| Vapor Density | 0.07 (lighter than air) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 3468
Extinguishing Media
PPE Requirements
Use SCBA for fire or confined spaces, flame-resistant antistatic protective clothing and eye/face protection. Avoid ignition sources and damaged storage modules.
Isolation & Evacuation
First Actions for a UN 3468 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.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers, equipment 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 115, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3468 — Hydrogen in a metal hydride storage systUse 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.