☣️ UN 3518 • CLASS 2
Adsorbed gas, poisonous, oxidizing, 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 3518
Class: 2
Placard type: Toxic Gas
ERG: Guide 173 (check current ERG)
Isolation: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind in all directions; if tank/container involved in fire, evacuate 1600m radius
Chemical & Response Details
| Also known as | Adsorbed gas, toxic, oxidizing, corrosive, n.o.s.Compressed gas, poisonous, oxidizing, corrosive, n.o.s.Toxic oxidizing corrosive gas adsorbedHazard Zone A adsorbed gas |
| Appearance | Gaseous material adsorbed onto a porous solid substrate. Specific color and odor depend on the actual gas involved; may be colorless or colored with irritating or pungent odor. |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | Not applicable (varies by specific gas) |
| Vapor Density | Not applicable (gas form) |
| Water Reactivity | May react with water or moisture; reaction severity depends on specific gas. Potential for violent reaction producing corrosive or toxic fumes. |
| Extinguishing | Do not use water or foam; dry chemical or inert gas only if applicable |
| PPE | ⚠️ Level A required; fully encapsulated chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard requiring maximum respiratory and skin protection |
| Isolation | ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind in all directions; if tank/container involved in fire, evacuate 1600m radius |
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 3518 — Adsorbed gas, poisonous, oxidizing, corr HAZMAT RADIO NOTE — UN 3518
Product: Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 173
PPE: Level A required; fully encapsulated chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard requiring maximum respiratory and skin protection
ISOLATION: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind in all directions; if tank/container involved in fire, evacuate 1600m radius
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 3518 — Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
Appearance: Gaseous material adsorbed onto a porous solid substrate. Specific color and odor depend on the actual gas involved; may be colorless or colored with irritating or pungent odor.
Water Reactivity: May react with water or moisture; reaction severity depends on specific gas. Potential for violent reaction producing corrosive or toxic fumes.
Extinguishing: Do not use water or foam; dry chemical or inert gas only if applicable
PPE: Level A required; fully encapsulated chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard requiring maximum respiratory and skin protection
Isolation: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind in all directions; if tank/container involved in fire, evacuate 1600m radius
— 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/3518 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3518 Adsorbed gas, poisonous, oxidizing, corrosive, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG173 | allfirefighter.com/hazmat/un/3518SMS / 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/3518
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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 chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard requiring maximum respiratory and skin protection
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.