# Guide 173: Adsorbed Gases - Toxic*

- **operation:** document
- **citation:** ERG 2024 Guide 173
- **title:** Guide 173: Adsorbed Gases - Toxic*
- **source type:** guidance
- **agency:** U.S. DOT / Transport Canada / SICT
- **status:** guidance
- **official:** true
- **published on:** 2024-04-04
- **effective on:** Not available
- **summary:** ERG2024 response Guide 173: Adsorbed Gases - Toxic*.
- **machine formats:** - **json:** https://regulus.evalyn.ai/document/phmsa-erg-2024-guide-173.json
- **markdown:** https://regulus.evalyn.ai/document/phmsa-erg-2024-guide-173.md
- **app url:** https://regulus.evalyn.ai/document/phmsa-erg-2024-guide-173
- **source url:** https://www.phmsa.dot.gov/erg/guide?number=173
**body:**

GUIDE
173
Adsorbed Gases - Toxic*
POTENTIAL HAZARDS
HEALTH
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TOXIC; may be fatal if inhaled or absorbed through skin.
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Vapors may be irritating.
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Contact with gas may cause burns and injury.
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Fire will produce irritating, corrosive and/or toxic gases.
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Runoff from fire control or dilution water may cause environmental contamination.
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FIRE OR EXPLOSION
Some gases may burn or be ignited by heat, sparks or flames.
May form explosive mixtures with air.
Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
transportation pressures.
Vapors may travel to source of ignition and flash back.
Some of these materials may react violently with water.
Cylinders exposed to fire may vent and release toxic and flammable gas through pressure relief devices.
Runoff may create fire hazard.
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.).
Ventilate closed spaces before entering, but only if properly trained and equipped.
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PROTECTIVE CLOTHING
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Wear positive pressure self-contained breathing apparatus (SCBA).
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Wear chemical protective clothing that is specifically recommended by the manufacturer when there is
NO RISK OF FIRE.
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Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.
EVACUATION
Immediate precautionary measure
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Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
Spill
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See Table 1 - Initial Isolation and Protective Action Distances.
Fire
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If several small packages (inside a railcar or trailer) are 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.
*  Some substances may also be flammable, corrosive
and/or oxidizing
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ERG 2024

Adsorbed Gases - Toxic* GUIDE
173
EMERGENCY RESPONSE
FIRE
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DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED.
Small Fire
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Dry chemical, CO2, water spray or alcohol-resistant foam.
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For UN3515, UN3518, UN3520, use water only; no dry chemical, CO2 or Halon®.
Large Fire
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Water spray, fog or alcohol-resistant foam.
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Do not get water inside containers.
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If it can be done safely, move undamaged containers away from the area around the fire.
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Damaged cylinders should be handled only by specialists.
Fire Involving Several Small Packages (inside a railcar or trailer)
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Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.
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Cool containers with flooding quantities of water until well after fire is out.
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Do not direct water at source of leak or safety devices.
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Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.
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ALWAYS stay away from tanks in direct contact with flames.
SPILL OR LEAK
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Some gases may be flammable. ELIMINATE all ignition sources (no smoking, flares, sparks or flames)
from immediate area.
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For flammable gases, all equipment used when handling the product must be grounded.
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For oxidizing substances, keep combustibles (wood, paper, oil, etc.) away from spilled material.
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Do not touch or walk through spilled material.
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Stop leak if you can do it without risk.
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Do not direct water at spill or source of leak.
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Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled
material.
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Prevent entry into waterways, sewers, basements or confined areas.
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Isolate area until gas has dispersed.
FIRST AID
Refer to the “General First Aid” section.
Specific First Aid:
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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
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