☣️ UN 3512 • CLASS 2
UN 3512 — Adsorbed gas, poisonous, 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 3512 Quick Details
UN 3512
Product name: Adsorbed gas, poisonous, 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/leak 100m all directions; initial evacuation 800m downwind daytime, increase at night or if large spill
Common Hazards of UN 3512
- 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 | Toxic gas adsorbedPoisonous gas adsorbedAdsorbed toxic gas n.o.s.Inhalation Hazard Zone A gas |
| Appearance | Variable appearance depending on specific gas; typically colorless to pale colored gas adsorbed onto porous solid material in cylinders. Odor varies by specific substance, may be odorless or have characteristic smell. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (varies by specific adsorbed gas) |
| Vapor Density | Heavier than air (typical for toxic gases) |
| Water Reactivity | Variable; depends on specific gas identity - may react or be inert |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3512
Extinguishing Media
Not applicable for gas release; evacuate area and allow dispersion
PPE Requirements
⚠️ Level A required; full encapsulating suit with SCBA; extreme toxicity requires maximum protection
Isolation & Evacuation
ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind daytime, increase at night or if large spill
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 173).
First Actions for a UN 3512 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 3512 — Adsorbed gas, poisonous, n.o.s. (InhalatHAZMAT RADIO NOTE — UN 3512
Product: Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 173
PPE: Level A required; full encapsulating suit with SCBA; extreme toxicity requires maximum protection
ISOLATION: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind daytime, increase at night or if large spill
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 3512 — Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
Appearance: Variable appearance depending on specific gas; typically colorless to pale colored gas adsorbed onto porous solid material in cylinders. Odor varies by specific substance, may be odorless or have characteristic smell.
Water Reactivity: Variable; depends on specific gas identity - may react or be inert
Extinguishing: Not applicable for gas release; evacuate area and allow dispersion
PPE: Level A required; full encapsulating suit with SCBA; extreme toxicity requires maximum protection
Isolation: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind daytime, increase at night or if large spill
— 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/3512 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3512 Adsorbed gas, poisonous, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG173 | allfirefighter.com/hazmat/un/3512SMS / 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/3512
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Frequently Asked Questions about UN 3512
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 encapsulating suit with SCBA; extreme toxicity requires maximum protection
Water reactivity: Variable; depends on specific gas identity - may react or be inert. Recommended extinguishing: Not applicable for gas release; evacuate area and allow dispersion.
ERG Guide 173 recommendation: ERG 173: Isolate spill/leak 100m all directions; initial evacuation 800m downwind daytime, increase at night or if large spill
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.