☣️ UN 3504 • CLASS 2
UN 3504 — Chemical under pressure, flammable, poisonous, n.o.s.
Placard: Flammable Gas. ERG Guide 119. 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 3504 Quick Details
UN 3504
Product name: Chemical under pressure, flammable, poisonous, n.o.s.
DOT Class: 2
Placard type: Flammable Gas
ERG Guide: 119 (check current ERG)
Initial isolation: ERG 119: Small spill isolate 100m all directions. Large spill isolate 800m all directions, evacuate 1600m downwind during day or 3200m at night.
Common Hazards of UN 3504
- TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Flammable; may be ignited by heat, sparks or flames.
- May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
Chemical Identity & Physical Properties
| Also known as | Chemical under pressure, flammable, toxic, n.o.s.Compressed chemical, flammable, poisonousPressurized flammable toxic chemical |
| Appearance | Compressed or liquefied gas or chemical mixture under pressure. May be colorless or colored depending on specific chemical. Flammable and toxic with potentially irritating or pungent odor. |
| Flash Point | Not applicable (compressed gas) |
| Boiling Point | Varies depending on specific chemical composition |
| Vapor Density | Typically heavier than air when released |
| Water Reactivity | Variable; depends on specific chemical composition. Use caution with water application. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3504
Extinguishing Media
Water spray to cool containers, dry chemical, CO2. Avoid direct water stream on leak.
PPE Requirements
⚠️ Level A required for unknown composition. Full-face SCBA, chemical-resistant suit with gloves. Gas-tight suit for high concentrations or confined spaces.
Isolation & Evacuation
ERG 119: Small spill isolate 100m all directions. Large spill isolate 800m all directions, evacuate 1600m downwind during day or 3200m at night.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 119).
First Actions for a UN 3504 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.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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📋 Copy & Share Field Card
UN 3504 — Chemical under pressure, flammable, poisHAZMAT RADIO NOTE — UN 3504
Product: Chemical under pressure, flammable, poisonous, n.o.s.
Class 2 / Flammable Gas / ERG 119
PPE: Level A required for unknown composition. Full-face SCBA, chemical-resistant suit with gloves. Gas-tight suit for high concentrations or confined spaces.
ISOLATION: ERG 119: Small spill isolate 100m all directions. Large spill isolate 800m all directions, evacuate 1600m downwind during day or 3200m at night.
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 3504 — Chemical under pressure, flammable, poisonous, n.o.s.
Class: 2 | Placard: Flammable Gas | ERG Guide: 119
Appearance: Compressed or liquefied gas or chemical mixture under pressure. May be colorless or colored depending on specific chemical. Flammable and toxic with potentially irritating or pungent odor.
Water Reactivity: Variable; depends on specific chemical composition. Use caution with water application.
Extinguishing: Water spray to cool containers, dry chemical, CO2. Avoid direct water stream on leak.
PPE: Level A required for unknown composition. Full-face SCBA, chemical-resistant suit with gloves. Gas-tight suit for high concentrations or confined spaces.
Isolation: ERG 119: Small spill isolate 100m all directions. Large spill isolate 800m all directions, evacuate 1600m downwind during day or 3200m at night.
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
• Fire will produce irritating, corrosive and/or toxic gases.
— 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/3504 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3504 Chemical under pressure, flammable, poisonous, n.o.s. Cls2 ERG119 | allfirefighter.com/hazmat/un/3504SMS / 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/3504
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Frequently Asked Questions about UN 3504
TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Flammable; may be ignited by heat, sparks or flames. May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Vapors from liquefied gas are initially heavier than air and spread along ground.
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 for unknown composition. Full-face SCBA, chemical-resistant suit with gloves. Gas-tight suit for high concentrations or confined spaces.
Water reactivity: Variable; depends on specific chemical composition. Use caution with water application.. Recommended extinguishing: Water spray to cool containers, dry chemical, CO2. Avoid direct water stream on leak..
ERG Guide 119 recommendation: ERG 119: Small spill isolate 100m all directions. Large spill isolate 800m all directions, evacuate 1600m downwind during day or 3200m at night.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 119 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.