☣️ UN 3517 • CLASS 2
Adsorbed gas, poisonous, flammable, 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 3517
Class: 2
Placard type: Toxic Gas
ERG: Guide 173 (check current ERG)
Isolation: ERG 173: Initial isolation 200m all directions; protective action distance 3.7km daytime, 8.0km nighttime for large spills; immediate evacuation of spill area
Chemical & Response Details
| 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 |
| Extinguishing | Do not use water or foam; use dry chemical or CO2 from safe distance only if necessary |
| PPE | ⚠️ Level A required; fully encapsulated suit with SCBA; toxic by inhalation Zone A requires maximum protection; avoid any skin or eye contact |
| Isolation | ERG 173: Initial isolation 200m all directions; protective action distance 3.7km daytime, 8.0km nighttime for large spills; immediate evacuation of spill area |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
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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UN 3517 — Adsorbed gas, poisonous, flammable, corr HAZMAT RADIO NOTE — UN 3517
Product: Adsorbed gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 173
PPE: Level A required; fully encapsulated suit with SCBA; toxic by inhalation Zone A requires maximum protection; avoid any skin or eye contact
ISOLATION: ERG 173: Initial isolation 200m all directions; protective action distance 3.7km daytime, 8.0km nighttime for large spills; immediate evacuation of spill area
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 3517 — Adsorbed gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
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.
Water Reactivity: May react with water or moisture producing corrosive and toxic fumes; avoid water contact
Extinguishing: Do not use water or foam; use dry chemical or CO2 from safe distance only if necessary
PPE: Level A required; fully encapsulated suit with SCBA; toxic by inhalation Zone A requires maximum protection; avoid any skin or eye contact
Isolation: ERG 173: Initial isolation 200m all directions; protective action distance 3.7km daytime, 8.0km nighttime for large spills; immediate evacuation of spill area
— 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/3517 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3517 Adsorbed gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG173 | allfirefighter.com/hazmat/un/3517SMS / 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/3517
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FAQ
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; fully encapsulated suit with SCBA; toxic by inhalation Zone A requires maximum protection; avoid any skin or eye contact
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.