☣️ UN 3311 • CLASS 2
UN 3311 — Gas, refrigerated liquid, oxidizing, n.o.s.
Placard: Non-Flammable Gas. ERG Guide 122. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
UN 3311 covers refrigerated liquid oxidizing gases. These cryogenic liquids can rapidly vaporize, displace air, support combustion, and cause severe frostbite on contact.
Hazard overview: The material does not burn, but it can accelerate combustion and may react dangerously with fuels. Cold vapor clouds can spread along the ground and create asphyxiation and cryogenic burn hazards.
Response guidance: Keep fuels and combustibles away, isolate the leak area, and cool exposed containers from a safe distance when directed. Avoid contact with the liquid and control ignition sources around oxygen-enriched atmospheres.
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UN 3311 Quick Details
UN 3311
Product name: Gas, refrigerated liquid, oxidizing, n.o.s.
DOT Class: 2
Placard type: Non-Flammable Gas
ERG Guide: 122 (check current ERG)
Initial isolation: ERG 122: isolate 800m (1/2 mile) all directions initially; evacuate 1600m (1 mile) downwind if tank is involved in fire
Common Hazards of UN 3311
- Substance does not burn but will support combustion.
- Some may react explosively with fuels.
- May ignite combustibles (wood, paper, oil, clothing, etc.).
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Runoff may create fire or explosion hazard.
- Containers may explode when heated.
- Ruptured cylinders may rocket.
- Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
Chemical Identity & Physical Properties
Cryogenic liquid maintained at very low temperatures (typically below -150°C). Color and odor vary depending on specific gas; typically colorless to pale colored liquid that rapidly boils and evaporates at ambient temperature producing dense white vapor clouds.
| Also known as | Cryogenic oxidizing gasRefrigerated liquefied oxidizing gasCryogenic liquid oxidizerLiquefied oxidizing gas |
| Appearance | Cryogenic liquid maintained at very low temperatures (typically below -150°C). Color and odor vary depending on specific gas; typically colorless to pale colored liquid that rapidly boils and evaporates at ambient temperature producing dense white vapor clouds. |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | Varies by specific gas, typically -150°C to -183°C (-238°F to -297°F) |
| Vapor Density | Varies by gas; most oxidizing gases are heavier than air when cold |
| Water Reactivity | No significant reaction with water, but extreme cold can cause violent boiling and splashing |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3311
Extinguishing Media
Do not use water or foam; use dry chemical or CO2 for small fires; flood area with water from safe distance for large fires
PPE Requirements
⚠️ Level A or B with SCBA required; insulated cryogenic gloves and face shield mandatory; avoid contact with liquid (severe frostbite hazard)
Level A or B with SCBA required; insulated cryogenic gloves and face shield mandatory; avoid contact with liquid (severe frostbite hazard)
Isolation & Evacuation
ERG 122: isolate 800m (1/2 mile) all directions initially; evacuate 1600m (1 mile) downwind if tank is involved in fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 122).
First Actions for a UN 3311 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- Consider initial downwind evacuation for at least 500 meters (1/3 mile).
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📋 Copy & Share Field Card
UN 3311 — Gas, refrigerated liquid, oxidizing, n.oHAZMAT RADIO NOTE — UN 3311
Product: Gas, refrigerated liquid, oxidizing, n.o.s.
Class 2 / Non-Flammable Gas / ERG 122
PPE: Level A or B with SCBA required; insulated cryogenic gloves and face shield mandatory; avoid contact with liquid (severe frostbite hazard)
ISOLATION: ERG 122: isolate 800m (1/2 mile) all directions initially; evacuate 1600m (1 mile) downwind if tank is involved in fire
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3311 — Gas, refrigerated liquid, oxidizing, n.o.s.
Class: 2 | Placard: Non-Flammable Gas | ERG Guide: 122
Appearance: Cryogenic liquid maintained at very low temperatures (typically below -150°C). Color and odor vary depending on specific gas; typically colorless to pale colored liquid that rapidly boils and evaporates at ambient temperature producing dense white vapor clouds.
Water Reactivity: No significant reaction with water, but extreme cold can cause violent boiling and splashing
Extinguishing: Do not use water or foam; use dry chemical or CO2 for small fires; flood area with water from safe distance for large fires
PPE: Level A or B with SCBA required; insulated cryogenic gloves and face shield mandatory; avoid contact with liquid (severe frostbite hazard)
Isolation: ERG 122: isolate 800m (1/2 mile) all directions initially; evacuate 1600m (1 mile) downwind if tank is involved in fire
— Key Hazards —
• Substance does not burn but will support combustion.
• Some may react explosively with fuels.
• May ignite combustibles (wood, paper, oil, clothing, etc.).
— First Actions —
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
• Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
SOURCE: allfirefighter.com/hazmat/un/gas-refrigerated-liquid-oxidizing-un-3311 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3311 Gas, refrigerated liquid, oxidizing, n.o.s. Cls2 ERG122 | allfirefighter.com/hazmat/un/gas-refrigerated-liquid-oxidizing-un-3311SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/gas-refrigerated-liquid-oxidizing-un-3311
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Frequently Asked Questions about UN 3311
No. It is not flammable, but it is oxidizing and can make other materials burn more intensely.
Contact with refrigerated liquid can cause severe frostbite and cold burns.
Yes. Oxidizing refrigerated gases can ignite or intensify combustible materials.
SCBA, face protection, insulated cryogenic gloves, and protective clothing are needed for release response.
Water may be used from a safe distance for fire control or cooling, but direct contact with cryogenic liquid can cause violent boiling.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.