☣️ UN 3516 • CLASS 2
Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A)
Placard: Toxic Gas. 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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Quick details
UN 3516
Class: 2
Placard type: Toxic Gas
ERG: Guide 173 (check current ERG)
Verify shipping papers and exact product details; use ERG Guide 173 for initial actions and isolation/evacuation guidance.
Common hazards (high level)
- 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
First actions (field-minded)
- 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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MAYDAY / HAZMAT QUICK NOTE UN 3516 — Adsorbed gas, poisonous, corrosive, n.o.s. (Inhalation Hazard Zone A) Class: 2 | Placard: Toxic Gas ERG: Guide 173 (check current ERG) FIRST ACTIONS: use SOP/SOG + ERG; stage upwind; isolate; deny entry; request Hazmat.
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FAQ
A UN/NA number is a four-digit identifier used in transport markings and placards to help identify hazardous materials for emergency response.
No. This page is a training/quick-reference aid. Always consult the current ERG and follow your SOP/SOG for incident-specific protective actions.
Common locations include placards, orange panels, shipping papers, SDS documents, container markings, rail car/vehicle IDs, and facility signage.
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.