UN 2201 — Nitrous oxide, refrigerated liquid
Placard: Non-Flammable Gas. ERG Guide 122. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2201 is Nitrous oxide, refrigerated liquid, a refrigerated oxidizing gas assigned to ERG Guide 122. It is not flammable but supports combustion and causes cryogenic injury.
Hazard overview: NON-FLAMMABLE oxidizing refrigerated liquid; does not burn but strongly supports combustion. Can intensify fire and may react dangerously with fuels, oils, grease or other combustibles. Contact with refrigerated liquid or cold vapor can cause severe frostbite and cryogenic burns.
Response guidance: For a UN 2201 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 122. 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 2201 should emphasize exposure routes, air monitoring, PPE selection, fire behavior, decontamination, runoff containment and ERG/SDS verification. Use ERG 122, SDS and local SOP.
Regulatory context: Nitrous oxide, refrigerated liquid 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: Nitrous oxide, refrigerated liquid 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 2201 Quick Details
Common Hazards of UN 2201
- NON-FLAMMABLE oxidizing refrigerated liquid; does not burn but strongly supports combustion.
- Can intensify fire and may react dangerously with fuels, oils, grease or other combustibles.
- Contact with refrigerated liquid or cold vapor can cause severe frostbite and cryogenic burns.
- Vapor may displace oxygen or cause dizziness/asphyxiation in confined spaces.
- Containers may rupture or rocket when heated.
- Rapid vaporization can create cold vapor clouds near the release.
- Keep oil, grease and incompatible combustibles away from valves, fittings and cold surfaces.
Chemical Identity & Physical Properties
Colorless, odorless to slightly sweet-smelling cryogenic liquid that boils at very low temperature. Gas is also colorless with a faint sweet odor.
| Also known as | Laughing gasDinitrogen monoxideN2ONitrous oxide cryogenic liquidNitrogen oxide (N2O) |
| CAS Number | 10024-97-2 |
| Appearance | Colorless, odorless to slightly sweet-smelling cryogenic liquid that boils at very low temperature. Gas is also colorless with a faint sweet odor. |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | -88.5C (-127.3F) |
| Vapor Density | 1.53 (heavier than air) |
| Water Reactivity | No significant reaction with water; dissolves slightly |
Fireground Response Guidance — UN 2201
Extinguishing Media
PPE Requirements
Use SCBA and oxygen monitoring in confined or oxygen-deficient areas. Wear face shield, insulated/cryogenic gloves and protective clothing where liquefied or refrigerated gas contact is possible.
Isolation & Evacuation
First Actions for a UN 2201 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.
- 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 122, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2201 — Nitrous oxide, refrigerated liquidUse 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.