# Guide 116: Gases - Flammable (Unstable)

**Citation:** ERG 2024 Guide 116  
**Type / status:** guidance / guidance  
**Agency:** U.S. DOT / Transport Canada / SICT  
**Effective:** Not stated  
**Published:** 2024-04-04

ERG2024 response Guide 116: Gases - Flammable (Unstable).

## Document text

GUIDE
116
Gases - Flammable (Unstable)
POTENTIAL HAZARDS
FIRE OR EXPLOSION
•
EXTREMELY FLAMMABLE.
•
Will be easily ignited by heat, sparks or flames.
•
Will form explosive mixtures with air. Acetylene (UN1001, UN3374) may react explosively even in the
absence of air.
•
Disilane (UN3553) and Silane (UN2203) will ignite spontaneously in air and may re-ignite.
•
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.
•
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.
•
•
•
•
HEALTH
Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.
Some may be toxic if inhaled at high concentrations.
Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
Fire may produce irritating and/or toxic gases.
PUBLIC SAFETY
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
not available or no answer, refer to appropriate telephone number listed on the inside back cover.
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
(sewers, basements, tanks, etc.).
•
•
•
•
PROTECTIVE CLOTHING
•
Wear positive pressure self-contained breathing apparatus (SCBA).
•
Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.
EVACUATION
Immediate precautionary measure
•
•
•
Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
Large Spill
Consider initial downwind evacuation for at least 800 meters (1/2 mile).
Fire
If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all
directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.
Page 162
ERG 2024

Gases - Flammable (Unstable)
GUIDE
116
EMERGENCY RESPONSE
FIRE
•
DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED.
Small Fire
•
Dry chemical or CO2.
Large Fire
•
Water spray or fog.
•
If it can be done safely, move undamaged containers away from the area around the fire.
Fire Involving Tanks
•
Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.
•
Cool containers with flooding quantities of water until well after fire is out.
•
Do not direct water at source of leak or safety devices; icing may occur.
•
Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.
•
ALWAYS stay away from tanks in direct contact with flames.
•
For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw
from area and let fire burn.
SPILL OR LEAK
•
ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.
•
All equipment used when handling the product must be grounded.
•
Stop leak if you can do it without risk.
•
Do not touch or walk through spilled material.
•
Do not direct water at spill or source of leak.
•
Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled
material.
•
If possible, turn leaking containers so that gas escapes rather than liquid.
•
Prevent entry into waterways, sewers, basements or confined areas.
•
Isolate area until gas has dispersed.
FIRST AID
Refer to the “General First Aid” section.
Specific First Aid:
•
In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts.
•
In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove
clothing if adhering to skin.
In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product.
Please consult the shipping paper and/or the "ERAP" section.
ERG 2024
Page 163

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/erg/guide?number=116>
- Source ID: `phmsa-erg-2024`
- SHA-256: `601545ab32a4e49154bbf23d6ff9cbc4e8e821d636b09c2941589755e63bb51f`
- Retrieved: 2026-08-13T11:31:32.574Z
- Exported: 2026-08-22T14:19:36.081Z
- Document slug: `phmsa-erg-2024-guide-116`

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