UN 3511 — Adsorbed gas, n.o.s.
Placard: Non-Flammable Gas. ERG Guide 174. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3511 is Adsorbed gas, n.o.s., a pressurized hazardous material assigned to ERG Guide 174. The exact contents should be verified from shipping papers and the SDS before close-range action.
Hazard overview: Primary hazards include fire or vapor ignition, container rupture. Adsorbed gas, n.o.s. may release irritating, toxic or corrosive vapors when heated, spilled or involved in fire, so avoid contact, inhalation and incompatible materials.
Response guidance: For a UN 3511 incident, establish incident command, isolate the area, stay upwind and uphill, keep unauthorized personnel away, verify shipping papers/SDS and follow ERG 174. Use extinguishing, cooling, containment and decontamination tactics only when compatible with the material and local SOP.
UN 3511 Quick Details
Common Hazards of UN 3511
- Some gases will be ignited by heat, sparks or flames.
- Substance does not burn but will support combustion.
- Vapors may travel to source of ignition and flash back.
- Cylinders exposed to fire may vent and release flammable gas through pressure relief devices.
- Containers may explode when exposed to prolonged direct flame impingement.
- Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
- Some may be irritating if inhaled at high concentrations.
- Contact with gas may cause burns and injury.
Chemical Identity & Physical Properties
Gas adsorbed onto porous solid material (activated carbon, molecular sieves, etc.). Physical appearance depends on the specific gas and adsorbent; typically a solid container with adsorbed gas molecules. The gas itself may be colorless and odorless or have characteristic properties depending on identity.
| Also known as | Adsorbed gas not otherwise specifiedAdsorbed gas NOSGas adsorbed on solid medium |
| Appearance | Gas adsorbed onto porous solid material (activated carbon, molecular sieves, etc.). Physical appearance depends on the specific gas and adsorbent; typically a solid container with adsorbed gas molecules. The gas itself may be colorless and odorless or have characteristic properties depending on identity. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (varies by specific gas component) |
| Vapor Density | Varies depending on specific gas; generally heavier than air for most industrial gases |
| Water Reactivity | Generally no significant reaction, though depends on specific gas adsorbed |
Fireground Response Guidance — UN 3511
Extinguishing Media
PPE Requirements
Level B minimum with SCBA required; full chemical protective clothing if gas identity unknown or presents toxic inhalation hazard
Isolation & Evacuation
First Actions for a UN 3511 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 800 meters (1/2 mile).
📋 Copy & Share Field Card
UN 3511 — Adsorbed gas, 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.