☣️ UN 3157 • CLASS 2
Liquefied gas, oxidizing, 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 3157
Class: 2
Placard type: Non-Flammable Gas
ERG: Guide 122 (check current ERG)
Isolation: ERG 122: Initial isolation 100m in all directions. Protective action distance: 0.3 km (0.2 mi) for spills/leaks during day, 0.8 km (0.5 mi) at night. Large spill: 0.5 km (0.3 mi) day, 1.4 km (0.9 mi) night. Fire: evacuate 800m radius.
Chemical & Response Details
| Also known as | Oxidizing liquefied gasCompressed oxidizing gasLiquefied oxidizer gasOxidizing gas under pressure |
| Appearance | Colorless to pale yellow liquefied gas stored under pressure. Odorless or may have faint chemical odor. Becomes gaseous when released to atmosphere at normal temperatures. |
| Flash Point | Not applicable (non-flammable oxidizing gas) |
| Boiling Point | Varies by specific oxidizer; typically below room temperature when liquefied under pressure |
| Vapor Density | Varies by specific gas; generally heavier than air (>1.0) |
| Water Reactivity | No significant reaction with water, but may increase fire intensity if combustibles are present |
| Extinguishing | Do not use water or foam. Use dry chemical or CO2 for small fires involving combustibles ignited by this gas. Flooding amounts of water may be used to cool containers. |
| PPE | ⚠️ Level B minimum with SCBA required. Full protective clothing and face shield for potential liquid contact (frostbite hazard). Self-contained breathing apparatus mandatory in confined spaces or release areas. |
| Isolation | ERG 122: Initial isolation 100m in all directions. Protective action distance: 0.3 km (0.2 mi) for spills/leaks during day, 0.8 km (0.5 mi) at night. Large spill: 0.5 km (0.3 mi) day, 1.4 km (0.9 mi) night. Fire: evacuate 800m radius. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Substance does not burn but will support combustion.
- Some may react explosively with fuels.
- May ignite combustibles (wood, paper, oil, clothing, etc.).
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Runoff may create fire or explosion hazard.
- Containers may explode when heated.
- Ruptured cylinders may rocket.
- Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
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 500 meters (1/3 mile).
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UN 3157 — Liquefied gas, oxidizing, n.o.s. HAZMAT RADIO NOTE — UN 3157
Product: Liquefied gas, oxidizing, n.o.s.
Class 2 / Non-Flammable Gas / ERG 122
PPE: Level B minimum with SCBA required. Full protective clothing and face shield for potential liquid contact (frostbite hazard). Self-contained breathing apparatus mandatory in confined spaces or release areas.
ISOLATION: ERG 122: Initial isolation 100m in all directions. Protective action distance: 0.3 km (0.2 mi) for spills/leaks during day, 0.8 km (0.5 mi) at night. Large spill: 0.5 km (0.3 mi) day, 1.4 km (0.9 mi) night. Fire: evacuate 800m 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 3157 — Liquefied gas, oxidizing, n.o.s.
Class: 2 | Placard: Non-Flammable Gas | ERG Guide: 122
Appearance: Colorless to pale yellow liquefied gas stored under pressure. Odorless or may have faint chemical odor. Becomes gaseous when released to atmosphere at normal temperatures.
Water Reactivity: No significant reaction with water, but may increase fire intensity if combustibles are present
Extinguishing: Do not use water or foam. Use dry chemical or CO2 for small fires involving combustibles ignited by this gas. Flooding amounts of water may be used to cool containers.
PPE: Level B minimum with SCBA required. Full protective clothing and face shield for potential liquid contact (frostbite hazard). Self-contained breathing apparatus mandatory in confined spaces or release areas.
Isolation: ERG 122: Initial isolation 100m in all directions. Protective action distance: 0.3 km (0.2 mi) for spills/leaks during day, 0.8 km (0.5 mi) at night. Large spill: 0.5 km (0.3 mi) day, 1.4 km (0.9 mi) night. Fire: evacuate 800m radius.
— Key Hazards —
• Substance does not burn but will support combustion.
• Some may react explosively with fuels.
• May ignite combustibles (wood, paper, oil, clothing, etc.).
— 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/3157 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3157 Liquefied gas, oxidizing, n.o.s. Cls2 ERG122 | allfirefighter.com/hazmat/un/3157SMS / 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/3157
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FAQ
Substance does not burn but will support combustion. Some may react explosively with fuels. May ignite combustibles (wood, paper, oil, clothing, etc.). Vapors from liquefied gas are initially heavier than air and spread along ground. Runoff may create fire or explosion hazard. Containers may explode when heated. Ruptured cylinders may rocket. Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
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 protective clothing and face shield for potential liquid contact (frostbite hazard). Self-contained breathing apparatus mandatory in confined spaces or release areas.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 122 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.