# Guide 138: Substances - Water-Reactive (Emitting Flammable Gases)

**Citation:** ERG 2024 Guide 138  
**Type / status:** guidance / guidance  
**Agency:** U.S. DOT / Transport Canada / SICT  
**Effective:** Not stated  
**Published:** 2024-04-04

ERG2024 response Guide 138: Substances - Water-Reactive (Emitting Flammable Gases).

## Document text

GUIDE
138
Substances - Water-Reactive
(Emitting Flammable Gases)
POTENTIAL HAZARDS
FIRE OR EXPLOSION
•
Produce flammable gases on contact with water.
•
May ignite on contact with water or moist air.
•
Some react vigorously or explosively on contact with water.
•
May be ignited by heat, sparks or flames.
•
May re-ignite after fire is extinguished.
•
Some are transported in highly flammable liquids.
•
Runoff may create fire or explosion hazard.
•
•
•
•
HEALTH
Inhalation or contact with vapors, substance or decomposition products may cause severe injury or
death.
May produce corrosive solutions on contact with water.
Fire will produce irritating, corrosive and/or toxic gases.
Runoff from fire control or dilution water may cause environmental contamination.
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.
Ventilate closed spaces before entering, but only if properly trained and equipped.
•
•
•
•
PROTECTIVE CLOTHING
•
Wear positive pressure self-contained breathing apparatus (SCBA).
•
Wear chemical protective clothing that is specifically recommended by the manufacturer when there is
NO RISK OF FIRE.
•
Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.
EVACUATION
Immediate precautionary measure
•
Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
(75 feet) for solids.
Large Spill
•
•
Consider initial downwind evacuation for at least 300 meters (1000 feet).
Fire
If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all
directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
Page 206
ERG 2024

Substances - Water-Reactive
(Emitting Flammable Gases)
GUIDE
138
EMERGENCY RESPONSE
FIRE
•
DO NOT USE WATER OR FOAM.
Small Fire
•
Dry chemical, soda ash, lime or sand.
Large Fire
•
DRY sand, dry chemical, soda ash or lime or withdraw from area and let fire burn.
•
If it can be done safely, move undamaged containers away from the area around the fire.
Fire Involving Metals or Powders (Aluminum, Lithium, Magnesium, etc.)
•
Use dry chemical, DRY sand, sodium chloride powder, graphite powder or class D extinguishers; in
addition, for Lithium you may use Lith-X® powder or copper powder. Also, see GUIDE 170.
Fire Involving Tanks, Rail Tank Cars or Highway Tanks
•
Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.
•
Do not get water inside containers.
•
Cool containers with flooding quantities of water until well after fire is out.
•
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.
SPILL OR LEAK
•
ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.
•
Do not touch or walk through spilled material.
•
Stop leak if you can do it without risk.
•
Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact
spilled material.
•
DO NOT GET WATER on spilled substance or inside containers.
Small Spill
•
Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to
minimize spreading or contact with rain.
•
Dike for later disposal; do not apply water unless directed to do so.
Powder Spill
•
Cover powder spill with plastic sheet or tarp to minimize spreading and keep powder dry.
•
DO NOT CLEAN-UP OR DISPOSE OF, EXCEPT UNDER SUPERVISION OF A SPECIALIST.
FIRST AID
Refer to the “General First Aid” section.
Specific First Aid:
•
at least 20 minutes.
In case of contact with substance, wipe from skin immediately; flush skin or eyes with running water for
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 207

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/erg/guide?number=138>
- Source ID: `phmsa-erg-2024`
- SHA-256: `fc38f8eb14edd678e23c4dcb3f85e738860ac7edcdae60d9bce583963d17d0d7`
- Retrieved: 2026-08-13T11:31:32.574Z
- Exported: 2026-08-22T20:03:04.667Z
- Document slug: `phmsa-erg-2024-guide-138`

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