UN 3512 — Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A)
Placard: Toxic Gas. ERG Guide 173. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3512 is Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A), a pressurized hazardous material assigned to ERG Guide 173. The exact contents should be verified from shipping papers and the SDS before close-range action.
Hazard overview: Primary hazards include toxic exposure, corrosive burns, fire or vapor ignition, container rupture. Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A) 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 3512 incident, establish incident command, isolate the area, stay upwind and uphill, keep unauthorized personnel away, verify shipping papers/SDS and follow ERG 173. Use extinguishing, cooling, containment and decontamination tactics only when compatible with the material and local SOP.
UN 3512 Quick Details
Common Hazards of UN 3512
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating.
- Contact with gas may cause burns and injury.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some gases may burn or be ignited by heat, sparks or flames.
- May form explosive mixtures with air.
- Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
Chemical Identity & Physical Properties
Variable appearance depending on specific gas; typically colorless to pale colored gas adsorbed onto porous solid material in cylinders. Odor varies by specific substance, may be odorless or have characteristic smell.
| Also known as | Toxic gas adsorbedPoisonous gas adsorbedAdsorbed toxic gas n.o.s.Inhalation Hazard Zone A gas |
| Appearance | Variable appearance depending on specific gas; typically colorless to pale colored gas adsorbed onto porous solid material in cylinders. Odor varies by specific substance, may be odorless or have characteristic smell. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (varies by specific adsorbed gas) |
| Vapor Density | Heavier than air (typical for toxic gases) |
| Water Reactivity | Variable; depends on specific gas identity - may react or be inert |
Fireground Response Guidance — UN 3512
Extinguishing Media
PPE Requirements
Level A required; full encapsulating suit with SCBA; extreme toxicity requires maximum protection
Isolation & Evacuation
First Actions for a UN 3512 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.
- See Table 1 - Initial Isolation and Protective Action Distances.
📋 Copy & Share Field Card
UN 3512 — Adsorbed gas, poisonous, n.o.s. (InhalatUse 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.