☣️ UN 3158 • CLASS 2
Gas, refrigerated liquid, 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 3158
Class: 2
Placard type: Non-Flammable Gas
ERG: Guide 120 (check current ERG)
Isolation: ERG 120: Isolate spill 100m all directions; if tank/railcar involved in fire, isolate 800m and consider evacuation 1600m downwind
Chemical & Response Details
| Also known as | Refrigerated liquefied gas n.o.s.Cryogenic liquid gas n.o.s.LNG (generic)Liquefied cryogenic gas |
| Appearance | Colorless to pale liquid when refrigerated, boiling and producing vapors at ambient temperature. Odor varies by specific gas. Extremely cold (-150°C to -200°C range) cryogenic liquid. |
| Flash Point | Not applicable (varies by specific gas composition) |
| Boiling Point | Varies by gas (-150°C to -200°C typical range for cryogenic liquids) |
| Vapor Density | Initially heavier than air when released, spreads along ground |
| Water Reactivity | No significant reaction with water, but rapid vaporization may occur |
| Extinguishing | Not applicable for cryogenic liquids; use water spray to vaporize, dry chemical or CO2 for fires |
| PPE | ⚠️ Level B minimum with cryogenic gloves; SCBA required in confined spaces; full face shield and insulated clothing for liquid contact |
| Isolation | ERG 120: Isolate spill 100m all directions; if tank/railcar involved in fire, isolate 800m and consider evacuation 1600m downwind |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Contact with gas, liquefied gas or cryogenic liquids may cause burns, severe injury and/or frostbite.
- Non-flammable gases.
- Containers may explode when heated.
- Ruptured cylinders may rocket.
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 100 meters (330 feet).
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UN 3158 — Gas, refrigerated liquid, n.o.s. HAZMAT RADIO NOTE — UN 3158
Product: Gas, refrigerated liquid, n.o.s.
Class 2 / Non-Flammable Gas / ERG 120
PPE: Level B minimum with cryogenic gloves; SCBA required in confined spaces; full face shield and insulated clothing for liquid contact
ISOLATION: ERG 120: Isolate spill 100m all directions; if tank/railcar involved in fire, isolate 800m and consider evacuation 1600m downwind
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 3158 — Gas, refrigerated liquid, n.o.s.
Class: 2 | Placard: Non-Flammable Gas | ERG Guide: 120
Appearance: Colorless to pale liquid when refrigerated, boiling and producing vapors at ambient temperature. Odor varies by specific gas. Extremely cold (-150°C to -200°C range) cryogenic liquid.
Water Reactivity: No significant reaction with water, but rapid vaporization may occur
Extinguishing: Not applicable for cryogenic liquids; use water spray to vaporize, dry chemical or CO2 for fires
PPE: Level B minimum with cryogenic gloves; SCBA required in confined spaces; full face shield and insulated clothing for liquid contact
Isolation: ERG 120: Isolate spill 100m all directions; if tank/railcar involved in fire, isolate 800m and consider evacuation 1600m downwind
— Key Hazards —
• Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
• Vapors from liquefied gas are initially heavier than air and spread along ground.
• Contact with gas, liquefied gas or cryogenic liquids may cause burns, severe injury and/or frostbite.
— 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/3158 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3158 Gas, refrigerated liquid, n.o.s. Cls2 ERG120 | allfirefighter.com/hazmat/un/3158SMS / 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/3158
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FAQ
Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas. Vapors from liquefied gas are initially heavier than air and spread along ground. Contact with gas, liquefied gas or cryogenic liquids may cause burns, severe injury and/or frostbite. Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket.
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 cryogenic gloves; SCBA required in confined spaces; full face shield and insulated clothing for liquid contact
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 120 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.