UN 3516 — Adsorbed gas, poisonous, 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 3516 is Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A), a Zone A toxic corrosive adsorbed gas entry assigned to ERG Guide 173. Corrosive gas release and inhalation toxicity are critical.
Hazard overview: Adsorbed gas package containing toxic 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 3516, 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 3516 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, 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, 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 3516 Quick Details
Common Hazards of UN 3516
- Adsorbed gas package containing toxic 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.
- Corrosive gas can burn eyes, skin and respiratory tissue.
- Water or moisture may form acids or other corrosive/toxic fumes depending on the gas.
- Runoff or vapor-control water may be toxic and corrosive.
- Containers exposed to fire may vent, rupture or release toxic gas.
Chemical Identity & Physical Properties
Compressed gas adsorbed onto a solid porous material in a cylinder. May be colorless or visible depending on specific gas. Corrosive and toxic properties vary by specific chemical identity.
| Also known as | Adsorbed toxic gas NOSAdsorbed poisonous corrosive gasUN3516 adsorbed gasToxic corrosive gas adsorbed |
| Appearance | Compressed gas adsorbed onto a solid porous material in a cylinder. May be colorless or visible depending on specific gas. Corrosive and toxic properties vary by specific chemical identity. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (compressed gas) |
| Vapor Density | Varies by specific gas; typically heavier than air |
| Water Reactivity | May react with water producing corrosive or toxic fumes depending on specific gas identity |
Fireground Response Guidance — UN 3516
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 3516 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.
- 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 3516 — Adsorbed gas, poisonous, corrosive, n.o.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.