UN 3517 — Adsorbed gas, poisonous, flammable, 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 3517 is Adsorbed gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A), a Zone A toxic flammable corrosive adsorbed gas entry assigned to ERG Guide 173. Flashback and inhalation lethality drive response.
Hazard overview: Adsorbed gas package containing toxic flammable 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 3517, 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 3517 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, flammable, 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, flammable, 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 3517 Quick Details
Common Hazards of UN 3517
- Adsorbed gas package containing toxic flammable 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.
- Flammable gas may form explosive mixtures with air and flash back to the release source.
- Corrosive gas can burn eyes, skin and respiratory tissue.
- Fire may produce toxic and corrosive combustion products.
- Containers exposed to fire may vent, rupture or release toxic gas.
Chemical Identity & Physical Properties
Gas adsorbed onto porous solid material in cylinder. Physical properties depend on specific gas identity. Typically colorless to pale colored gas when released, may have irritating or pungent odor.
| Also known as | Adsorbed toxic gas N.O.S.Adsorbed poisonous gas flammable corrosiveCompressed toxic gas adsorbedAdsorbed gas Inhalation Hazard Zone A |
| Appearance | Gas adsorbed onto porous solid material in cylinder. Physical properties depend on specific gas identity. Typically colorless to pale colored gas when released, may have irritating or pungent odor. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (varies by specific gas composition) |
| Vapor Density | Heavier than air (typical for toxic corrosive gases) |
| Water Reactivity | May react with water or moisture producing corrosive and toxic fumes; avoid water contact |
Fireground Response Guidance — UN 3517
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 3517 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.
- Eliminate ignition sources if this can be done safely.
- 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 3517 — Adsorbed gas, poisonous, flammable, 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.