UN 3518 — Adsorbed gas, poisonous, oxidizing, corrosive, 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 3518 is Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A), a Zone A toxic oxidizing corrosive adsorbed gas entry assigned to ERG Guide 173. Oxidizer/fire compatibility and corrosive release matter.
Hazard overview: Adsorbed gas package containing toxic oxidizing corrosive gas; release may create an immediate inhalation hazard. Inhalation Hazard Zone A entries may be fatal at very low airborne concentrations. Gas is held on a porous solid adsorbent, but damage, heating or valve failure can release free gas.
Response guidance: For UN 3518, isolate downwind/low areas, treat as a life-threatening gas release and use Level A/SCBA for entry. Verify exact gas with shipping papers and ERG 173.
Firefighter training notes: Training for UN 3518 should emphasize toxic-gas recognition, Zone A isolation, Level A/SCBA entry, air monitoring, source-control limits and decontamination. Use ERG 173, SDS and local SOP.
Regulatory context: Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A) is regulated as a hazardous material for transport and emergency response. Storage, reporting, exposure, waste and incident-notification duties depend on quantity, package type, gas identity and jurisdiction; verify shipping papers, SDS and authority guidance.
Storage & handling: Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A) should be stored in secured compatible adsorbed-gas packages away from heat, impact, corrosion, moisture where incompatible and unauthorized access, with ventilation and emergency planning.
UN 3518 Quick Details
Common Hazards of UN 3518
- Adsorbed gas package containing toxic oxidizing corrosive gas; release may create an immediate inhalation hazard.
- Inhalation Hazard Zone A entries may be fatal at very low airborne concentrations.
- Gas is held on a porous solid adsorbent, but damage, heating or valve failure can release free gas.
- Released gas behavior, odor warning and vapor density depend on the exact gas identity.
- Oxidizing gas may intensify fire involving combustibles or oils.
- Corrosive gas can burn eyes, skin and respiratory tissue.
- Water or moisture may create toxic/corrosive products and contaminated runoff.
- Containers exposed to fire may vent, rupture or release toxic gas.
Chemical Identity & Physical Properties
Gaseous material adsorbed onto a porous solid substrate. Specific color and odor depend on the actual gas involved; may be colorless or colored with irritating or pungent odor.
| Also known as | Adsorbed gas, toxic, oxidizing, corrosive, n.o.s.Compressed gas, poisonous, oxidizing, corrosive, n.o.s.Toxic oxidizing corrosive gas adsorbedHazard Zone A adsorbed gas |
| Appearance | Gaseous material adsorbed onto a porous solid substrate. Specific color and odor depend on the actual gas involved; may be colorless or colored with irritating or pungent odor. |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | Not applicable (varies by specific gas) |
| Vapor Density | Not applicable (gas form) |
| Water Reactivity | May react with water or moisture; reaction severity depends on specific gas. Potential for violent reaction producing corrosive or toxic fumes. |
Fireground Response Guidance — UN 3518
Extinguishing Media
PPE Requirements
Use Level A fully encapsulating chemical protective clothing with positive-pressure SCBA for entry. Zone A toxic gas requires maximum respiratory and skin protection.
Isolation & Evacuation
First Actions for a UN 3518 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind and avoid low or poorly ventilated areas unless monitoring shows they are safe.
- Treat the release as a life-threatening inhalation hazard until the gas is identified and monitored.
- Keep fuels, oils, greases, combustibles and reducing agents away from oxidizing gas.
- Do not handle leaking cylinders, adsorbed-gas packages or damaged gas articles without proper training and PPE.
- Ventilate only after monitoring and only if properly trained and equipped.
- Use ERG Guide 173, shipping papers, markings and air monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 3518 — Adsorbed gas, poisonous, oxidizing, corrUse 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.