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 At a Glance
UN 3523 (Germane, adsorbed) is listed as DOT Class 2 Toxic Gas and is assigned to ERG Guide 173. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.