UN 2203 — Silane
Placard: Flammable Gas. ERG Guide 116. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2203 is Silane, a pyrophoric extremely flammable gas assigned to ERG Guide 116. It can ignite spontaneously in air and re-ignite.
Hazard overview: PYROPHORIC and EXTREMELY FLAMMABLE gas; may ignite spontaneously in air. Can form explosive mixtures with air and may re-ignite after apparent extinguishment. Cylinders exposed to fire may vent flammable gas, rupture or rocket.
Response guidance: For a UN 2203 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 116. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2203 should emphasize toxic flammable gas behavior, source isolation, downwind monitoring, cylinder cooling, ignition control, Level A decisions and medical coordination. Use ERG 116, SDS and local SOP.
Regulatory context: Silane 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: Silane containers should be secured in a cool, ventilated gas storage area away from heat, physical damage and incompatible materials. Toxic, flammable, oxidizing, corrosive or refrigerated gases require leak detection/ventilation and emergency planning according to SDS and local code.
UN 2203 Quick Details
Common Hazards of UN 2203
- PYROPHORIC and EXTREMELY FLAMMABLE gas; may ignite spontaneously in air.
- Can form explosive mixtures with air and may re-ignite after apparent extinguishment.
- Cylinders exposed to fire may vent flammable gas, rupture or rocket.
- Gas may travel to ignition sources and flash back.
- Contact with rapidly expanding or liquefied gas may cause frostbite.
- Fire may produce silicon oxide smoke and irritating gases.
- Remote operations and source isolation are preferred.
Chemical Identity & Physical Properties
Colorless gas with a repulsive, garlic-like or rotten fish odor. Pyrophoric — ignites spontaneously in air at room temperature above approximately 21°C (70°F).
| Also known as | Silicon tetrahydrideMonosilaneSilicon hydrideSiH4 |
| CAS Number | 7803-62-5 |
| Appearance | Colorless gas with a repulsive, garlic-like or rotten fish odor. Pyrophoric — ignites spontaneously in air at room temperature above approximately 21°C (70°F). |
| Flash Point | Not applicable (pyrophoric gas, ignites spontaneously in air) |
| Boiling Point | -112°C (-170°F) |
| Vapor Density | 1.1 (slightly heavier than air) |
| Water Reactivity | Reacts with water to produce hydrogen gas and silicon dioxide; reaction accelerates with heat |
Fireground Response Guidance — UN 2203
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fire-resistant protection for fire or leak response. Level A may be needed for unknown concentrations; remote operations are preferred because silane can ignite spontaneously.
Isolation & Evacuation
First Actions for a UN 2203 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 gas, vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Eliminate ignition sources if safe and treat the release as both toxic and flammable.
- Do not touch damaged containers or spilled/released 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, vapor/gas spread, cylinder heating, oxidizer reaction or unknown product identity.
- Use ERG Guide 116, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2203 — SilaneUse 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.