UN 3156 — Compressed gas, oxidizing, n.o.s.
Placard: Non-Flammable Gas. ERG Guide 122. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3156 is Compressed gas, oxidizing, n.o.s., a broad oxidizing gas entry assigned to ERG Guide 122. Exact gas identity controls combustion support and cylinder tactics.
Hazard overview: OXIDIZING compressed or liquefied gas, n.o.s.; does not burn but can greatly intensify fire. May ignite combustibles or react violently with fuels, oils, grease or reducing agents. Liquefied gas contact, where present, can cause frostbite or cold burns.
Response guidance: For UN 3156, isolate the cylinder or leak, keep fuels/oils/grease away and cool containers from protection. Verify exact gas before entry using SDS and ERG 122.
Firefighter training notes: Training for UN 3156 should emphasize cylinder/package recognition, vapor density, air monitoring, SCBA use, frostbite/toxicity controls, isolation and source-control limits. Use ERG 122, SDS and local SOP.
Regulatory context: Compressed gas, oxidizing, n.o.s. is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, formulation and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Compressed gas, oxidizing, n.o.s. should be stored in secured, compatible cylinders or sample packages away from heat, physical damage and unauthorized access, with ventilation, segregation and emergency planning based on exact gas identity.
UN 3156 Quick Details
Common Hazards of UN 3156
- OXIDIZING compressed or liquefied gas, n.o.s.; does not burn but can greatly intensify fire.
- May ignite combustibles or react violently with fuels, oils, grease or reducing agents.
- Liquefied gas contact, where present, can cause frostbite or cold burns.
- Vapors may displace oxygen or collect in low/confined areas depending on the exact gas.
- Cylinders exposed to fire may vent, rupture or rocket.
- Runoff or leaked liquid may create oxidizing contamination and fire intensification hazards.
- Exact gas identity must be verified from cylinder markings, SDS and shipping papers.
Chemical Identity & Physical Properties
Colorless to variably colored compressed gas depending on specific oxidizer. Odor varies by specific substance. Stored under pressure in cylinders or tanks at room temperature.
| Also known as | Oxidizing compressed gas N.O.S.Compressed oxidizing gasOxidizer compressed gas not otherwise specified |
| Appearance | Colorless to variably colored compressed gas depending on specific oxidizer. Odor varies by specific substance. Stored under pressure in cylinders or tanks at room temperature. |
| Flash Point | Not applicable (non-flammable gas) |
| Boiling Point | Not applicable (compressed gas, varies by specific oxidizer) |
| Vapor Density | Varies by specific oxidizer (typically heavier than air) |
| Water Reactivity | Generally no significant reaction, though specific oxidizers may vary |
Fireground Response Guidance — UN 3156
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for releases, fire or confined spaces. Wear eye/face protection and insulated gloves where liquefied or cryogenic gas contact is possible.
Isolation & Evacuation
First Actions for a UN 3156 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Keep fuels, oils, grease, organics and reducing agents away from the oxidizing gas.
- Do not touch damaged containers, cylinders, articles or spilled material without proper training and PPE.
- Prevent contaminated runoff, debris and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 122, SDS, shipping papers, markings and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3156 — Compressed gas, oxidizing, n.o.s.Use 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.