☣️ UN 1046 • CLASS 2
Helium, compressed
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 1046
Class: 2
Placard type: Non-Flammable Gas
ERG: Guide 120 (check current ERG)
Verify shipping papers and exact product details; use ERG Guide 120 for initial actions and isolation/evacuation guidance.
Chemical & Response Details
| Also known as | Helium gasHeHelium-4Compressed heliumLiquid helium |
| CAS Number | 7440-59-7 |
| Appearance | Colorless, odorless, tasteless inert gas at room temperature. Colorless liquid at cryogenic temperatures (-269°C). Lightest noble gas. |
| Flash Point | Not applicable (inert gas) |
| Boiling Point | -269°C (-452°F) |
| Vapor Density | 0.14 (lighter than air) |
| Water Reactivity | No reaction, inert gas |
| Extinguishing | Not applicable (inert gas); no extinguishing agents needed |
| PPE | ⚠️ Level D for gas release; Level A with SCBA for confined spaces or oxygen-deficient atmospheres; insulated gloves for cryogenic liquid contact |
| Isolation | ERG 121: Initial isolation 100m all directions; no evacuation distances for small spills; ventilate confined spaces to prevent asphyxiation |
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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MAYDAY / HAZMAT QUICK NOTE UN 1046 — Helium, compressed Class: 2 | Placard: Non-Flammable Gas ERG: Guide 120 (check current ERG) FIRST ACTIONS: use SOP/SOG + ERG; stage upwind; isolate; deny entry; request Hazmat.
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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 D for gas release; Level A with SCBA for confined spaces or oxygen-deficient atmospheres; insulated gloves for cryogenic 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.