☣️ UN 3501 • CLASS 2
UN 3501 — Chemical under pressure, flammable, n.o.s.
Placard: Flammable Gas. ERG Guide 115. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ 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.
UN 3501 is Chemical under pressure, flammable, n.o.s., a pressurized hazardous material assigned to ERG Guide 115. The exact contents should be verified from shipping papers and the SDS before close-range action.
Hazard overview: Primary hazards include fire or vapor ignition, container rupture. Chemical under pressure, flammable, n.o.s. may release irritating, toxic or corrosive vapors when heated, spilled or involved in fire, so avoid contact, inhalation and incompatible materials.
Response guidance: For a UN 3501 incident, establish incident command, isolate the area, stay upwind and uphill, keep unauthorized personnel away, verify shipping papers/SDS and follow ERG 115. Use extinguishing, cooling, containment and decontamination tactics only when compatible with the material and local SOP.
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UN 3501 Quick Details
UN 3501
Product name: Chemical under pressure, flammable, n.o.s.
DOT Class: 2
Placard type: Flammable Gas
ERG Guide: 115 (check current ERG)
Initial isolation: ERG 115: Initial isolation 100m in all directions; protective action distance 300m downwind for large spills during day, 800m at night
Common Hazards of UN 3501
- EXTREMELY FLAMMABLE.
- Will be easily ignited by heat, sparks or flames.
- Will form explosive mixtures with air.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- 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 heated.
- Ruptured cylinders may rocket.
Chemical Identity & Physical Properties
Variable appearance depending on specific chemical; typically a pressurized liquid or gas stored in containers under pressure at room temperature. May be colorless to colored liquid/gas with various odors depending on contents.
| Also known as | Chemical under pressure flammable NOSPressurized flammable chemicalAerosol flammable chemicalCompressed flammable chemical mixture |
| Appearance | Variable appearance depending on specific chemical; typically a pressurized liquid or gas stored in containers under pressure at room temperature. May be colorless to colored liquid/gas with various odors depending on contents. |
| Flash Point | Variable, typically below -18C (0F) for flammable gases or highly flammable liquids under pressure |
| Boiling Point | Variable depending on specific chemical contents and pressure conditions |
| Vapor Density | Variable, typically heavier than air for most flammable gases and vapors under pressure |
| Water Reactivity | Variable depending on specific chemical; many show no significant water reaction, but some flammable gases or chemicals may react |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3501
Extinguishing Media
Dry chemical, CO2, or foam appropriate for flammable liquids/gases; water spray for cooling containers only
PPE Requirements
⚠️ Level B minimum with SCBA required; full protective clothing and respiratory protection mandatory due to flammability and pressure release hazards
Level B minimum with SCBA required; full protective clothing and respiratory protection mandatory due to flammability and pressure release hazards
Isolation & Evacuation
ERG 115: Initial isolation 100m in all directions; protective action distance 300m downwind for large spills during day, 800m at night
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 115).
First Actions for a UN 3501 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- 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 3501 — Chemical under pressure, flammable, n.o.HAZMAT RADIO NOTE — UN 3501
Product: Chemical under pressure, flammable, n.o.s.
Class 2 / Flammable Gas / ERG 115
PPE: Level B minimum with SCBA required; full protective clothing and respiratory protection mandatory due to flammability and pressure release hazards
ISOLATION: ERG 115: Initial isolation 100m in all directions; protective action distance 300m downwind for large spills during day, 800m 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 3501 — Chemical under pressure, flammable, n.o.s.
Class: 2 | Placard: Flammable Gas | ERG Guide: 115
Appearance: Variable appearance depending on specific chemical; typically a pressurized liquid or gas stored in containers under pressure at room temperature. May be colorless to colored liquid/gas with various odors depending on contents.
Water Reactivity: Variable depending on specific chemical; many show no significant water reaction, but some flammable gases or chemicals may react
Extinguishing: Dry chemical, CO2, or foam appropriate for flammable liquids/gases; water spray for cooling containers only
PPE: Level B minimum with SCBA required; full protective clothing and respiratory protection mandatory due to flammability and pressure release hazards
Isolation: ERG 115: Initial isolation 100m in all directions; protective action distance 300m downwind for large spills during day, 800m at night
— Key Hazards —
• EXTREMELY FLAMMABLE.
• Will be easily ignited by heat, sparks or flames.
• Will form explosive mixtures with air.
— First Actions —
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• 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).
SOURCE: allfirefighter.com/hazmat/un/chemical-under-pressure-flammable-un-3501 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3501 Chemical under pressure, flammable, n.o.s. Cls2 ERG115 | allfirefighter.com/hazmat/un/chemical-under-pressure-flammable-un-3501SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/chemical-under-pressure-flammable-un-3501
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Frequently Asked Questions about UN 3501
UN 3501 is Chemical under pressure, flammable, n.o.s., assigned to ERG Guide 115.
ERG Guide 115 applies for initial isolation, protective actions and first response guidance.
Yes. Chemical under pressure, flammable, n.o.s. can present a fire, combustion or vapor ignition hazard; keep it away from heat, sparks and flames.
Pressurized containers may rupture, rocket or vent hazardous gas when heated or damaged.
Level B minimum with SCBA required; full protective clothing and respiratory protection mandatory due to flammability and pressure release hazards.
ERG 115: Initial isolation 100m in all directions; protective action distance 300m downwind for large spills during day, 800m at night.
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.