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 At a Glance
UN 3516 (Adsorbed gas, poisonous, corrosive (Inhalation Hazard Zone A)) is listed as DOT Class 2 Toxic Gas and is assigned to ERG Guide 173. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
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.