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ACETYLENE

2.1 - Flammable gas
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The Chemical Identifier fields include common identification numbers, the NFPA diamond U.S. Department of Transportation hazard labels, and a general description of the chemical. The information in CAMEO Chemicals comes from a variety of data sources.
CAS Number UN/NA Number
  • 74-86-2   (ACETYLENE)
DOT Hazard Label USCG CHRIS Code
  • Flammable Gas
NIOSH Pocket Guide International Chem Safety Card
Acetyleneexternal_link
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.

The Hazard fields include special hazard alerts air and water reactions, fire hazards, health hazards, a reactivity profile, and details about reactive groups assignments and potentially incompatible absorbents. The information in CAMEO Chemicals comes from a variety of data sources.
Reactivity Alerts
  • Highly Flammable
Air & Water Reactions
Highly flammable. Slightly soluble in water.
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]. 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.

The Response Recommendation fields include isolation and evacuation distances, as well as recommendations for firefighting, non-fire response, protective clothing, and first aid. The information in CAMEO Chemicals comes from a variety of data sources.
Isolation and Evacuation
Excerpt from ERG Guide 116 [Gases - Flammable (Unstable)]:

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, 2020)
Firefighting
Excerpt from ERG 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. 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 engulfed in fire. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2020)
Non-Fire Response
Excerpt from ERG Guide 116 [Gases - Flammable (Unstable)]:

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. (ERG, 2020)
Protective Clothing
Excerpt from NIOSH Pocket Guide for Acetyleneexternal link:

Skin: FROSTBITE - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Eyes: FROSTBITE - 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: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100°F).

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

Provide: FROSTBITE WASH - 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, 2023)
DuPont Tychem® Suit Fabrics
No information available.
First Aid
Excerpt from NIOSH Pocket Guide for Acetyleneexternal link:

Eye: FROSTBITE - 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: FROSTBITE - 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: FRESH AIR - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. Other measures are usually unnecessary. (NIOSH, 2023)

The Physical Property fields include properties such as vapor pressure and boiling point, as well as explosive limits and toxic exposure thresholds The information in CAMEO Chemicals comes from a variety of data sources.

Note: For Vapor Density and Specific Gravity, comparing the value to 1.0 can tell you if the chemical will likely sink/rise in air or sink/float in fresh water (respectively). Short phrases have been added to those values below as an aid. However, make sure to also consider the circumstances of a release. The Vapor Density comparisons are only valid when the gas escaping is at the same temperature as the surrounding air itself. If the chemical is escaping from a container where it was pressurized or refrigerated, it may first escape and behave as a heavy gas and sink in the air (even if it has a Vapor Density value less than 1). Also, the Specific Gravity comparisons are for fresh water (density 1.0 g/mL). If your spill is in salt water (density about 1.027 g/mL), you need to adjust the point of comparison. There are some chemicals that will sink in fresh water and float in salt water.
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, 2023)
Vapor Pressure: 44.2 atm (NIOSH, 2023)
Vapor Density (Relative to Air): 0.91 (NIOSH, 2023) - Lighter than air; will rise
Specific Gravity: 0.613 at -112°F (USCG, 1999) - Less dense than water; will float
Boiling Point: -119°F at 760 mmHg (USCG, 1999)
Molecular Weight: 26.04 (USCG, 1999)
Water Solubility: 2 % (NIOSH, 2023)
Ionization Energy/Potential: 11.40 eV (NIOSH, 2023)
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.
(DOE, 2018)

The Regulatory Information fields include information from the U.S. Environmental Protection Agency's Title III Consolidated List of Lists, the U.S. Cybersecurity and Infrastructure Security Agency's Chemical Facility Anti-Terrorism Standards, and the U.S. Occupational Safety and Health Administration's Process Safety Management of Highly Hazardous Chemicals Standard List (see more about these data sources).

EPA Consolidated List of Lists

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 pounds
Ethyne 74-86-2 10000 pounds

(EPA List of Lists, 2022)

CISA Chemical Facility Anti-Terrorism Standards (CFATS)

RELEASE THEFT SABOTAGE
Chemical of Interest CAS Number Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Acetylene; [Ethyne] 74-86-2 1.00 % 10000 pounds flammable

(CISA, 2007)

OSHA Process Safety Management (PSM) Standard List

No regulatory information available.

This section provides a listing of alternate names for this chemical, including trade names and synonyms.
  • ACETYLENE
  • ETHINE
  • ETHYNE
  • NARCYLEN
  • VINYLENE

Version 3.0.0