☣️ UN 3516 • CLASS 2
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.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 3516 Quick Details
UN 3516
Product name: Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A)
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 173 (check current ERG)
Initial isolation: ERG 173: Isolate spill or leak area immediately for at least 100 meters in all directions; evacuate 800 meters downwind if fire or large release; Inhalation Hazard Zone A requires maximum isolation
Common Hazards of UN 3516
- 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
| 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 |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3516
Extinguishing Media
Do not use water; evacuate area and allow gas to dissipate; use appropriate respiratory protection
PPE Requirements
⚠️ Level A required; full encapsulation with SCBA; chemical-resistant suit; corrosive and toxic gas protection mandatory
Isolation & Evacuation
ERG 173: Isolate spill or leak area immediately for at least 100 meters in all directions; evacuate 800 meters downwind if fire or large release; Inhalation Hazard Zone A requires maximum isolation
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 173).
First Actions for a UN 3516 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- 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.
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UN 3516 — Adsorbed gas, poisonous, corrosive, n.o.HAZMAT RADIO NOTE — UN 3516
Product: Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 173
PPE: Level A required; full encapsulation with SCBA; chemical-resistant suit; corrosive and toxic gas protection mandatory
ISOLATION: ERG 173: Isolate spill or leak area immediately for at least 100 meters in all directions; evacuate 800 meters downwind if fire or large release; Inhalation Hazard Zone A requires maximum isolation
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3516 — Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
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.
Water Reactivity: May react with water producing corrosive or toxic fumes depending on specific gas identity
Extinguishing: Do not use water; evacuate area and allow gas to dissipate; use appropriate respiratory protection
PPE: Level A required; full encapsulation with SCBA; chemical-resistant suit; corrosive and toxic gas protection mandatory
Isolation: ERG 173: Isolate spill or leak area immediately for at least 100 meters in all directions; evacuate 800 meters downwind if fire or large release; Inhalation Hazard Zone A requires maximum isolation
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating.
• Contact with gas may cause burns and injury.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/3516 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3516 Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG173 | allfirefighter.com/hazmat/un/3516SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/3516
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Frequently Asked Questions about UN 3516
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
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A required; full encapsulation with SCBA; chemical-resistant suit; corrosive and toxic gas protection mandatory
Water reactivity: May react with water producing corrosive or toxic fumes depending on specific gas identity. Recommended extinguishing: Do not use water; evacuate area and allow gas to dissipate; use appropriate respiratory protection.
ERG Guide 173 recommendation: ERG 173: Isolate spill or leak area immediately for at least 100 meters in all directions; evacuate 800 meters downwind if fire or large release; Inhalation Hazard Zone A requires maximum isolation
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 173 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.