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Chemical Datasheet

ACETYLENE

2.1 - Flammable gas

Chemical Identifiers

CAS Number UN/NA Number DOT Hazard Label CHRIS Code
  • 74-86-2   (ACETYLENE)
  • 1001
  • Flammable Gas
  • ACE
NFPA 704
Diamond Hazard Value Description
4
0 3
Blue Health 0 No hazard beyond that of ordinary combustible material.
Red Flammability 4 Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.
Yellow Instability 3 Capable of detonation or explosive decomposition or explosive reaction but requires a strong initiating source or must be heated under confinement before initiation.
White Special
(NFPA, 2010)
General Description
A colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

Hazards

Reactivity Alerts
Air & Water Reactions
Highly flammable. Slightly soluble in water. Reacts with water to form toxic ammonia fumes.
Fire Hazard
Behavior in Fire: May explode in fire (USCG, 1999)
Health Hazard
Headache, dizziness and loss of consciousness may occur. Death from ``smothering'' may occur if oxygen content of the air is severely reduced by dilution with acetylene. (USCG, 1999)
Reactivity Profile
ACETYLENE reacts with alkali metals, forming hydrogen gas. Acetylene can react explosively with bromine [Von Schwartz 1918. p.142]. Acetylene forms a sensitive acetylide when passed into an aqueous solution of mercuric nitrate [Mellor 4:933. 1946-47]. An acetylene torch used to drill through a plow frame, which was filled with hydrogen gas, produced an explosion [NIOSH, June 1998]. It reacts with silver, copper and lead to form sensitive, explosive salts. Since acetylene is endothermic and effectively a reducing agent, its reaction with oxidants can be very violent (examples: calcium hypochlorite, nitric acid, nitrogen oxide, ozone, trifluoromethyl hypofluorite, etc.). Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization, due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980]. Acetylene and ammonia can form explosive silver salts in contact with Ag. (Renner, Hermann, Gunther Schlamp. "Silver, Silver Compounds, and Silver Alloys." Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA. 2001.).
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

No information available.

Response Recommendations

Isolation and Evacuation
Excerpt from GUIDE 116 [Gases - Flammable (Unstable)]:

As an 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 car or tank truck 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. (ERG, 2012)
Firefighting
Excerpt from GUIDE 116 [Gases - Flammable (Unstable)]:

DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED.

SMALL FIRE: Dry chemical or CO2.

LARGE FIRE: Water spray or fog. Move containers from fire area if you can do it without risk.

FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned hose holders 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 engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2012)
Non-Fire Response
Excerpt from GUIDE 116 [Gases - Flammable (Unstable)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames in 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. (ERG, 2012)
Protective Clothing
Skin: Wear appropriate personal protective clothing to prevent skin from becoming frozen from contact with the liquid or from contact with vessels containing the liquid.

Eyes: Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation is made specifying the need for washing the substance from the skin (either immediately or at the end of the work shift).

Remove: Work clothing that becomes wet should be immediately removed due to its flammability hazard(i.e. for liquids with flash point < 100°F)

Change: No recommendation is made specifying the need for the worker to change clothing after the work shift.

Provide: Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating. (NIOSH, 2003)
DuPont Tychem® Suit Fabrics
No information available.
First Aid
Eye: If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible.

Skin: If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water. In order to prevent further tissue damage, do NOT attempt to remove frozen clothing from frostbitten areas. If frostbite has NOT occurred, immediately and thoroughly wash contaminated skin with soap and water.

Breathing: If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. Other measures are usually unnecessary. (NIOSH, 2003)

Physical Properties

Chemical Formula:
  • C2H2
Flash Point: data unavailable
Lower Explosive Limit (LEL): 2.5 % (USCG, 1999)
Upper Explosive Limit (UEL): 100 % (USCG, 1999)
Autoignition Temperature: 581 ° F (USCG, 1999)
Melting Point: -119 ° F (Sublimes) (NIOSH, 2003)
Vapor Pressure: 44.2 atm (NIOSH, 2003)
Vapor Density (Relative to Air): data unavailable
Specific Gravity: 0.613 at -112.0 ° F (USCG, 1999)
Boiling Point: -119 ° F at 760.0 mm Hg (USCG, 1999)
Molecular Weight: 26.04 (USCG, 1999)
Water Solubility: 2 % (NIOSH, 2003)
IDLH: data unavailable

AEGLs (Acute Exposure Guideline Levels)

No AEGL information available.

ERPGs (Emergency Response Planning Guidelines)

No ERPG information available.

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Acetylene (74-86-2) 65000 ppm 3-flame icon indicates value is 100% or more of LEL. 230000 ppm 3-flame icon indicates value is 100% or more of LEL. 400000 ppm 3-flame icon indicates value is 100% or more of LEL. LEL = 25000 ppm
3-flame icon indicates value is 100% or more of LEL.
(SCAPA, 2012)

Regulatory Information

Regulatory Name CAS Number/
313 Category Code
EPCRA 302
EHS TPQ
EPCRA 304
EHS RQ
CERCLA RQ EPCRA 313
TRI
RCRA
Code
CAA 112(r)
RMP TQ
Acetylene 74-86-2 10000
Ethyne 74-86-2 10000

(EPA List of Lists, 2012)

Alternate Chemical Names