UN 3523 — Germane, adsorbed
Placard: Toxic Gas. ERG Guide 173. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3523 is Germane, adsorbed, a toxic pyrophoric adsorbed germane gas assigned to ERG Guide 173. Air ignition and low-area vapor are key hazards.
Hazard overview: TOXIC and PYROPHORIC germane gas adsorbed on a porous solid; inhalation may be fatal. Released gas may ignite spontaneously in air and form explosive mixtures. Gas is heavier than air and may spread into low/confined areas before ignition.
Response guidance: For UN 3523, isolate downwind/low areas, treat as a life-threatening gas release and use Level A/SCBA for entry. Verify exact gas with shipping papers and ERG 173.
Firefighter training notes: Training for UN 3523 should emphasize toxic-gas recognition, Zone A isolation, Level A/SCBA entry, air monitoring, source-control limits and decontamination. Use ERG 173, SDS and local SOP.
Regulatory context: Germane, adsorbed is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, gas identity and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Germane, adsorbed should be stored in secured compatible adsorbed-gas packages away from heat, impact, corrosion, moisture where incompatible and unauthorized access, with ventilation and emergency planning.
UN 3523 Quick Details
Common Hazards of UN 3523
- TOXIC and PYROPHORIC germane gas adsorbed on a porous solid; inhalation may be fatal.
- Released gas may ignite spontaneously in air and form explosive mixtures.
- Gas is heavier than air and may spread into low/confined areas before ignition.
- Heating or package damage can release toxic flammable gas from the adsorbent.
- Fire may produce germanium oxide fumes and irritating/toxic smoke.
- Water or moisture can contribute to decomposition and hydrogen formation depending on conditions.
- Containers exposed to fire may vent, rupture or release gas.
Chemical Identity & Physical Properties
Colorless gas with a disagreeable odor at room temperature. Supplied as adsorbed compressed gas on a porous substrate in cylinders.
| Also known as | Germanium tetrahydrideGermanium hydrideMonogermaneGeH4 |
| CAS Number | 7782-65-2 |
| Appearance | Colorless gas with a disagreeable odor at room temperature. Supplied as adsorbed compressed gas on a porous substrate in cylinders. |
| Flash Point | Not applicable (pyrophoric gas, ignites spontaneously in air) |
| Boiling Point | -88C (-126F) |
| Vapor Density | 2.63 (heavier than air) |
| Water Reactivity | Decomposes slowly in water producing germanium dioxide and hydrogen; reaction accelerates with moisture |
Fireground Response Guidance — UN 3523
Extinguishing Media
PPE Requirements
Use Level A fully encapsulating chemical protective clothing with positive-pressure SCBA for entry. Zone A toxic gas requires maximum respiratory and skin protection.
Isolation & Evacuation
First Actions for a UN 3523 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind and avoid low or poorly ventilated areas unless monitoring shows they are safe.
- Treat the release as a life-threatening inhalation hazard until the gas is identified and monitored.
- Eliminate ignition sources if this can be done safely.
- Do not handle leaking cylinders, adsorbed-gas packages or damaged gas articles without proper training and PPE.
- Ventilate only after monitoring and only if properly trained and equipped.
- Use ERG Guide 173, shipping papers, markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3523 — Germane, adsorbedUse 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.