☣️ UN 3511 • CLASS 2
Adsorbed gas, n.o.s.
Placard: Non-Flammable 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 3511
Class: 2
Placard type: Non-Flammable Gas
ERG: Guide 174 (check current ERG)
Isolation: ERG 174: Initial isolation 100m in all directions; protective action distance 800m downwind during day if large spill
Chemical & Response Details
| Also known as | Adsorbed gas not otherwise specifiedAdsorbed gas NOSGas adsorbed on solid medium |
| Appearance | Gas adsorbed onto porous solid material (activated carbon, molecular sieves, etc.). Physical appearance depends on the specific gas and adsorbent; typically a solid container with adsorbed gas molecules. The gas itself may be colorless and odorless or have characteristic properties depending on identity. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Not applicable (varies by specific gas component) |
| Vapor Density | Varies depending on specific gas; generally heavier than air for most industrial gases |
| Water Reactivity | Generally no significant reaction, though depends on specific gas adsorbed |
| Extinguishing | Do not use water or foam; use dry chemical, CO2, or inert gas suppression for fires involving flammable adsorbed gases |
| PPE | ⚠️ Level B minimum with SCBA required; full chemical protective clothing if gas identity unknown or presents toxic inhalation hazard |
| Isolation | ERG 174: Initial isolation 100m in all directions; protective action distance 800m downwind during day if large spill |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Some gases will be ignited by heat, sparks or flames.
- Substance does not burn but will support combustion.
- Vapors may travel to source of ignition and flash back.
- Cylinders exposed to fire may vent and release flammable gas through pressure relief devices.
- Containers may explode when exposed to prolonged direct flame impingement.
- Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
- Some may be irritating if inhaled at high concentrations.
- Contact with gas may cause burns and injury.
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.
- Consider initial downwind evacuation for at least 800 meters (1/2 mile).
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UN 3511 — Adsorbed gas, n.o.s. HAZMAT RADIO NOTE — UN 3511
Product: Adsorbed gas, n.o.s.
Class 2 / Non-Flammable Gas / ERG 174
PPE: Level B minimum with SCBA required; full chemical protective clothing if gas identity unknown or presents toxic inhalation hazard
ISOLATION: ERG 174: Initial isolation 100m in all directions; protective action distance 800m downwind during day 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 3511 — Adsorbed gas, n.o.s.
Class: 2 | Placard: Non-Flammable Gas | ERG Guide: 174
Appearance: Gas adsorbed onto porous solid material (activated carbon, molecular sieves, etc.). Physical appearance depends on the specific gas and adsorbent; typically a solid container with adsorbed gas molecules. The gas itself may be colorless and odorless or have characteristic properties depending on identity.
Water Reactivity: Generally no significant reaction, though depends on specific gas adsorbed
Extinguishing: Do not use water or foam; use dry chemical, CO2, or inert gas suppression for fires involving flammable adsorbed gases
PPE: Level B minimum with SCBA required; full chemical protective clothing if gas identity unknown or presents toxic inhalation hazard
Isolation: ERG 174: Initial isolation 100m in all directions; protective action distance 800m downwind during day if large spill
— Key Hazards —
• Some gases will be ignited by heat, sparks or flames.
• Substance does not burn but will support combustion.
• Vapors may travel to source of ignition and flash back.
— 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/3511 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3511 Adsorbed gas, n.o.s. Cls2 ERG174 | ERG 174: Initial isolation 100m in all directions; protective action distance 80 | allfirefighter.com/hazmat/un/3511SMS / 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/3511
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FAQ
Some gases will be ignited by heat, sparks or flames. Substance does not burn but will support combustion. Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when exposed to prolonged direct flame impingement. Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas. Some may be irritating if inhaled at high concentrations. Contact with gas may cause burns and injury.
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 B minimum with SCBA required; full chemical protective clothing if gas identity unknown or presents toxic inhalation hazard
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 174 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.