Acetylene

Toxic Gases & Vapors -> Simple Asphyxiants

Flammable agents - 4th degree

log Kow = 0.37

0.37

Not unpleasant odor unless impure (due to phosphine)

FAINT ODOR OF ETHER

... Faint, ethereal odor [Note: Commercial grade has a garlic-like odor ...]

0.613 at -112 °F (USCG, 1999) - Less dense than water; will float

0.377 g/cu cm (pressure >1 atm)

1 L weighs 1.165 g at 0 °C and 760 mm Hg; density of gas: 0.90 (Air = 1); below 37 °C (critical temp) it liquifies at 68 atm; at 0 °C it liquifies at 21.5 atm

0.909 @ 0°C

0.91(relative gas density)

2 % (NIOSH, 2024)

In water, 1200 mg/L at 25 °C

Soluble in water and many organic materials

Slightly soluble in ethanol, carbon disulfide; soluble in acetone, benzene, chloroform

One volume dissolves in 6 volumes of glacial acetic acid or alcohol. Soluble in ether, benzene. Acetone dissolves 25 volume at 15 °C, 760 mm Hg; acetone dissolves 300 vol at 12 atm

Moderately soluble in ethanol and acetic acid; very soluble in Me2CO; almost miscible in ether

0 °F

Closed cup: -18.15 °C (-0.7 °F).

Flammable gas

NA (Gas)

-119 °F at 760 mmHg (USCG, 1999)

-84.7 °C (sublimation point)

BP: -84 °C sublimes

-84 °C @760 [mm Hg]

Sublimes

/Acetylene/, the extremely endothermic gas ... may decomposed explosively in absence of air ... /and/ readily escalates to detonation in tubular vessels. This type of explosive decomposition has been experienced in a 7 mile acetylene pipeline system ... Accidental local heating to 185 °C or above of part of the wall (as little as 6 sq cm may be enough) of a cylinder containing acetylene may lead to the development of an extremely dangerous situation. At this temperature, exothermic and self-sustaining decomposition of (endothermic) acetylene may set in, and if not stopped by rapid and effective cooling (large volume water spray), the cylinder may explode without warning. Flame flash-back into a cylinder from a wrongly adjusted and/or damaged welding or cutting torch can cause the same effect ...

Acetylene not dissolved in acetone may deflagrate above about 760 mm Hg absolute and becomes unstable at elevated pressures. It may decomposed into hydrogen and carbon with explosive violence.

... /Acetylene/ decomposes on heating and increasing pressure, causing fire and explosion hazard.

-119 °F (Sublimes) (NIOSH, 2024)

-80.7 °C (triple point)

-80.7 °C

-119 °F (Sublimes)

0.91 (NIOSH, 2024) - Lighter than air; will rise (Relative to Air)

0.91 (Air = 1)

Relative vapor density (air = 1): 0.907

Danger

H220: Extremely flammable gas [Danger Flammable gases]

P203, P210, P222, P280, P377, P381, and P403 (click each P-code to see the statement)

Danger

H220 (100%): Extremely flammable gas [Danger Flammable gases]

P203, P210, P222, P280, P377, P381, P403, and P410+P403 (click each P-code to see the statement)

Chemical: Ethyne

Ethyne is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Ethyne are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 18-05-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/15518

Ethyne (acetylene): HSNO Approval: HSR000987 Approved with controls

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Behavior in Fire: May explode in fire (USCG, 1999)

· EXTREMELY FLAMMABLE.

Extremely flammable. Gas/air mixtures are explosive.

Very dangerous fire hazard when exposed to heat or flame ...

Generation of acetylene, compression...& storage of cylinders...all entail fire...hazards...

Flammable gas ... Low ignition energy ... /Acetylene, dissolved/

... /Acetylene/ decomposes on heating and increasing pressure, causing fire and explosion hazard.

Extremely flammable.

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)

· Vapors may cause dizziness or asphyxiation without warning, especially when in closed or confined areas.

Acetylene is an explosive hazard and simple asphyxiant. [LaDou, p. 558] Possible frostbite from contact with liquid; [NIOSH] Acetylene is in the list of Some volatile substances which may be abused by inhalation published on the web site of the U.N. International Drug Control Programme, indicating its potential to cause narcosis in workers. [Reference #1]

1001 116

1001 116

European Chemicals Bureau; IUCLID Dataset, Acetylene (74-86-2) (2000 CD-ROM edition). Information on usage patterns, toxicity, and environmental effects supplied by industry to the European Union.[Available from, as of September 11, 2006: http://esis.jrc.ec.europa.eu/]

EPA/Office of Pollution Prevention and Toxics; High Production Volume (HPV) Challenge Program's Robust Summaries and Test Plans for Acetylene (December 2003). Evaluates information on usage patterns, toxicity, and environmental effects supplied by industry to the U.S. EPA HPV Challenge Program.[Available from, as of April 6, 2014: http://www.epa.gov/chemrtk/pubs/summaries/acetylen/c15005.pdf]

Excerpt from ERG Guide 116 [Gases - Flammable (Unstable)]:

Shut off supply; if not possible and no risk to surroundings, let the fire burn itself out. In other cases extinguish with powder, carbon dioxide. In case of fire: keep cylinder cool by spraying with water.

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

· 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.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

Excerpt from NIOSH Pocket Guide for Acetylene:

General First Aid:

(General first aid procedures)

On loss of containment this gas can cause suffocation by lowering the oxygen content of the air in confined areas.

Simple asphyxiant. /Acetylene, dissolved/

Stop flow of gas before extinguishing fire. Use water spray to keep fire-exposed containers cool. Approach fire from upwind to avoid hazardous vapors and toxic decomposition products. Fight fire from protected location or maximum possible distance. Use water spray, dry chemical, form, or carbon dioxide. /Acetylene, dissolved/

Stop flow of gas. ... Carbon dioxide, dry chemical and water spray are not generally recommended because the discharged gas or volatile liquid may create a more serious explosion hazard.

If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. /Acetylene, dissolved; Acetylene, solvent free/

Evacuation: If fire becomes uncontrollable or container is exposed to direct flame - consider evacuation of one-third (1/3) mile radius. ... /Acetylene, dissolved; Acetylene, solvent free/

For more Fire Fighting Procedures (Complete) data for ACETYLENE (9 total), please visit the HSDB record page.

Keep container in a cool, well-ventilated area. Keep container tightly closed and sealed until ready for use. Avoid all possible sources of ignition (spark or flame). Segregate from oxidizing materials. Cylinders should be stored upright, with valve protection cap in place, and firmly secured to prevent falling or being knocked over. Cylinder temperatures should not exceed 52 degC (125 degF).

Acetylene can be stored as a gas or in solution. Gaseous acetylene becomes highly explosive when compressed or heated and consequently it is stored under low pressure in large tanks or gasholders.

Outside or detached storage is preferred. Isolate from oxidizing gases, especially chlorine. Store in a cool , dry, well-ventilated location. Store cylinders upright. /Acetylene, dissolved/

Acetylene in process may be stored in atmospheric gas holders. May be stored in conventional compressed gas cylinders. Content of lines carrying acetylene must not exceed 63% copper (Cu). Storage of liquid acetylene should be avoided.

Evacuate danger area! Consult an expert! Ventilation. Remove all ignition sources. (Extra personal protection: self-contained breathing apparatus).

Eliminate all ignition sources. Stop or control the leak, if this can be done without undue risk. Use water spray to cool and disperse vapors and protect personnel. /Acetylene, dissolved/

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Gas Leakage. By forced ventilation, maintain concentration of gas below the range of explosive mixture. Remove the tank or cylinder to an open area. Leave to bleed off in the atmosphere. Disposal. Fit a pipe line into a furnace or into a pit and burn with care.

Product removed from the cylinder must be disposed of in accordance with appropriate Federal, State, local regulation. ... Do not dispose of locally.

/Acetylene/ produces varying degrees of temporary and reversible /CNS depression/ when administered with oxygen in concentrations of 100,000 ppm ...

In humans, the author reported a stimulation of respiration by acetylene-oxygen mixtures (700000 - 800000 ppm). However, all but two of the seven subjects studied had been premedicated with a morphine-containing preparation which affects respiration.

The authors observed a rise in the blood pressure of cats administered acetylene-oxygen mixtures containing up to 800000 ppm. No increase was observed if the anesthetic was administered slowly and carefully.

Respiration in cats and rabbits was decreased when acetylene-oxygen mixtures were administered.

For more Interactions (Complete) data for ACETYLENE (7 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 2(SRC), determined from a log Kow of 0.37(2) and a regression-derived equation(3), indicates that acetylene is expected to have very high mobility in soil(SRC). Volatilization of acetylene from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.2X10-2 atm-cu m/mole(SRC), derived from its vapor pressure, 3.65X10+4 mm Hg(4), and water solubility, 1,200 mg/L(5). Acetylene is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). A 0% theoretical BOD in 28 days using an activated sludge inoculum in the Japanese MITI test(6) suggests that biodegradation is not expected to be an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 2(SRC), determined from a log Kow of 0.37(2) and a regression-derived equation(3), indicates that acetylene is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 2.2X10-2 atm-cu m/mole(SRC), derived from its vapor pressure, 3.65X10+4 mm Hg(5), and water solubility, 1,200 mg/L(6). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 1.5 hrs and 2 days, respectively(SRC). According to a classification scheme(7), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). A 0% theoretical BOD in 28 days using an activated sludge inoculum in the Japanese MITI test(8) suggests that biodegradation is not expected to be an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), acetylene, which has a vapor pressure of 3.65X10+4 mm Hg at 25 °C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase acetylene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 20 days(SRC), calculated from its rate constant of 8.15X10-13 cu cm/molecule-sec at 25 °C(3). Acetylene has a calculated global lifetimes ranging from 14 days(4) to 32 days(5) in the atmosphere. Acetylene does not contain chromophores that absorb at wavelengths >290 nm(6) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

The substance can be absorbed into the body by inhalation.

inhalation, skin and/or eye contact (liquid)

Dizziness. Lethargy. Headache. Suffocation.

headache, dizziness; asphyxia; liquid: frostbite

Acetylene was found in whole gas octane levels 87, 89 and 92 at 0.0022, 0.0032 and 0.0037 ppbC%, respectively(1). Acetylene has been detected 12%, 2.9% and 50% of total hydrocarbon concentration in emissions from vehicle exhaust, petroleum exhaust and petrochemical plants, respectively(2). Acetylene has been estimated to be about 12.69% of total organic gases released in exhaust from small engines(3). Acetylene was released from catalyst and non-catalyst equipped gasoline powered motor vehicle tailpipes at concentrations of 12,800 and 865,00 ug/km, respectively(4). Hydrocarbon speciation of acetylene in exhaust emissions typically are 0.0376, 0.0, and 0.0% of engine exhaust under cold start, hot stab, and hot start exhaust emissions, respectively(5). Acetylene in the air at bus garages and from motorcycle emissions in Egypt comprised of 1.3-1.7 and 3.38% by weight, respectively, of the non-methane organic contaminants in these areas(6).

Acetylene was released from the pyrolysis and combustion of scrap tire at the concentrations ranging from 0.73-1.07 and 0.002-0.54 mg/100 mg of scrap tire(1).

Acetylene comprised of 4.11, 0.34, 0.77 and 1.24% of nonmethane organic carbon emissions monitored in restaurants, tortilla, rotisserie and fried food in Mexico(1).

The Koc of acetylene is estimated as 2(SRC), using a log Kow of 0.37(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that acetylene is expected to have very high mobility in soil. Less than 1 ppm of gas acetylene was absorbed to dry soil and a maximum of 90 ppm of acetylene was absorbed to moist soil samples taken from 6 soil samples from Oregon, Iowa and Saskatchewan, Canada(4).

Acetylene was present in fine particle emissions from burning of Lobolly pine, Western Hemlock, Ponderosa pine (Pinaceae), Aceraceae/Fagaceae, Palmae/Pinaceae, and Poaceae/Pinaceae trees(1). Acetylene is released from burning wood in fireplaces and stoves(2).

URBAN/SUBURBAN: In Azuza, CA ambient acetylene value of 100 ug/cu m was measured during September 8-9 1993(1). Acetylene was found in 13/13 samples around the US during 1996 at concentrations greater than 1 ppbv(2). Acetylene was detected in the air of Taipei, Taiwan with a median concentration of 11,600 parts per trillion by volume(3). Industrial and downtown air from Edmonton, Canada during 1991-1993 had median concentrations of 2.19 and 5.89 ug/cu m, respectively(4). Acetylene was detected with a mean concentration of 40.2 mg/cu m in urban air from Porto Alegre, Brazil, March 1996-April 16, 1997(5). An observed ambient acetylene concentration of 16 ug/cu m was reported September 8-9,1993 in California south coast air(6). Acetylene was detected in 97% of the air samples taken from Washington, DC from March 1990 to March 1991 with a mean concentration of 16.1 ppbv(7). Acetylene was detected in background, residential and street site locations in Berlin, Germany from June to August 1996 in concentrations 0.47, 1.95 and 4.79 ug/cu m, respectively(8). Acetylene is labeled as one of the most prevalent non-methane organic compounds identified in urban air(9). The compound was detected at an average concentration of 4.01 ppbv in air samples from Beijing, China, sampled from June-September, 2008(10).

URBAN/SUBURBAN: ... expected ground level concentrations in USA urban air: 15 to 250 ppb

RURAL/REMOTE: Acetylene was present in air samples taken at Whiteface Mountain, Wilmington, NY, a rural mountain site in northeastern United States. Samples were collected during 12-16 July, 1994. Average concentrations were 4.2 and 3.5% of total carbon detected for nighttime and daytime, respectively. The remote site is affected by west-northesterly winds which advect photochemically-aged air masses that have been subject to anthropogenic emissions(1).

SOURCE DOMINATED: Acetylene in the air near roadways, lead smelter plants, and cast iron factories in Egypt comprised of 5.48, 0.12 and 0.40% by weight of the non-methane organic contaminants, respectively(1).

/HUMAN EXPOSURE STUDIES/ In humans, acetylene is not acutely toxic below its lower explosive limit of 2.5% (25,000 ppm). Inhalation of 10% acetylene (100,000 ppm) for 1 hour does not cause acute toxicity. Inhalation of 33% or 35% has caused unconsciousness within 7 and 5 minutes, respectively ...

/HUMAN EXPOSURE STUDIES/ Humans exposed to 35% acetylene were unconscious after 5 min. Commencing intoxication was observed after 25 sec, marked intoxication after 1 min.

/SIGNS AND SYMPTOMS/ A simple asphyxiant. High concentrations cause /CNS depression/. 20% concentration may cause dyspnea, headache; 40% or more concentration may cause collapse.

/SIGNS AND SYMPTOMS/ Acute local: 0. Chronic local: 0. Chronic systemic: inhalation 1. 0= none: no harm under any conditions or harmful only under unusual conditions or overwhelming dosage. 1= slight: causes readily reversible changes which disappear after end of exposure. Acute systemic: inhalation 2. 2= moderate: may involve both irreversible and reversible changes not severe enough to cause death or permanent injury.

For more Human Toxicity Excerpts (Complete) data for ACETYLENE (22 total), please visit the HSDB record page.

This action promulgates standards of performance for equipment leaks of Volatile Organic Compounds (VOC) in the Synthetic Organic Chemical Manufacturing Industry (SOCMI). The intended effect of these standards is to require all newly constructed, modified, and reconstructed SOCMI process units to use the best demonstrated system of continuous emission reduction for equipment leaks of VOC, considering costs, non air quality health and environmental impact and energy requirements. Acetylene is produced, as an intermediate or a final product, by process units covered under this subpart.

Acetylene

1

10000

Flammable chemical that can be released at a facility.

Acetylene alkylates the cytochrome P450 prothestic heme. This alkylation is coupled with catalytic turnover by the target enzyme and results in suicide inactivation of the enzymes. The oxidation of acetylene appears to result in the highly instable epoxide that rearranges to the keten. The structure of the prosthetic heme adduct is -CH2CHO.

Acetylene acts as a simple asphyxiant by diluting the oxygen in the air to a level which will not support life.

On loss of containment this substance /(acetylene)/ can cause suffocation by lowering the oxygen content of the air in confined areas.

... Acetylene-oxygen mixtures (750,000 to 800,000 ppm) produced an increase in blood pressure of patients during anesthesia ... attributable to stimulation of the vasomotor center.

Limited data reported in the literature indicate that acetylene is rapidly absorbed and eliminated unchanged in the body ... The blood-gas partition coefficient of acetylene at normal hematocrit and body temperature is 0.833 ... indicating that the material has a greater propensity to be removed from blood than to be retained in it ... In man at rest, the rates of alveolar and mixed venous washout for acetylene calculated from the slopes of the ... alveolar plateau are 2.6% and 4.8% per second, respectively. Within 10 minutes of inhalation of acetylene for 15 minutes, the end tidal concentration was 8.0 % of its initial value. Together, these data support the contention that the lungs rapidly excrete acetylene. The gas also diffuses rapidly from the peritoneal and pleural cavities and diffuses through the skin ...

... /Acetylene/ can be absorbed into the body by inhalation.

A compressed gas used in the welding and cutting of metals; Was used as a general anesthetic in the 1920's; [ACGIH]

Gas Welding and Cutting [Category: Weld]

Smoking cigarettes [Category: Food & Drugs]

Illuminant, oxyacetylene welding, cutting, and soldering metals, signaling; precipitating metals, particularly copper; manufacture of acetaldehyde, acetic acid

Used for brazing, ... metallizing, hardening, flame scarfing, and local heating in metallurgy. The flame is also used in the glass industry. Chemically, acetylene is used in the manufacture of ... synthetic rubber, ... butyrolactone, ... vinyl alkyl ether, pyrrolidone.

It is used for brazing, local heating & in glass industry.

Acetylene prepared from calcium carbide ... contains phosphine and some arsine ... up to 95 and 3 ppm respectively.

The most widely used method for producing acetylene is from calcium carbide and occasionally contains phosphine and arsine as impurities.

Crude acetylene frequently contains traces of ammonia, hydrogen sulfide, and phosphine, which are usually scrubbed out with caustic soda soln.

(1972) 1.02X10+9 GRAMS

(1975) 7.52X10+5 GRAMS

2023: 100,000,000 - <250,000,000 lb

Acetylene is listed as a High Production Volume (HPV) chemical (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).

(1972) 3.59X10+11 GRAMS

(1975) 2.10X10+11 GRAMS

(1984) 9.35X10+10 g /For chemical use only/

For more U.S. Production (Complete) data for ACETYLENE (8 total), please visit the HSDB record page.

26.5% For vinyl chloride; 21% for welding and metal cutting; 20% for acrylates and acrylic acid; 13.5% for vinyl acetate; 7% for tetrahydrofuran; 7% for acetylenic chemicals; 3% for chlorinated solvents; 2% for other chemicals (1974).

Vinyl Chloride, 23%; Vinyl Acetate, 9%; Acrylic Acid, 5%; 1,4-Butanediol & Derivatives, 26%; Miscellaneous Chemicals, 7%; Metal Cutting and Welding, 30% (1982).

CHEMICAL PROFILE: Acetylene. Vinyl chloride monomer, 40%; 1,4-butanediol, 27%; acetylene black, 5%; miscellaneous, including vinyl ethers, vinyl fluoride, acetylenic alcohols and fuel used in production of acetylenic chemicals, 28%.

CHEMICAL PROFILE: Acetylene. Demand: 1986: 330 million lb; 1987: 338 million lb; 1991 /projected/: 375 million lb.

In the year 2000, approximately 80% of US production was used as a closed system industrial intermediate in the synthesis of other chemicals ... The remaining 20% of production was predominantly used in oxyacetylene torches for welding and metal cutting ... Currently, 96% of manufacturing capacity of the 7 major manufacturers is slated for use as a closed system industrial intermediate.

Recovery from refinery gases; from petrochemical raw materials by thermal processes.

Manufactured from calcium carbide and water: Eastman, United States of America patent 3017259 (1962 to Texaco); from methane: Anderson, United States of America patent 3051639 (1962 to Union Carbide).

... Acetylene is obtained from gaseous hydrocarbons (eg methane) or liquid hydrocarbons (eg petroleum products) by partial combustion, electric arc or by high temp regenerative processes. Acetylene must then be separated from resultant gas mixture.

... By cracking petroleum hydrocarbons with steam (Wulff process), or natural gas by partial oxidation (BASF process); from fuel oil by modified arc process.

The major producers in the US manufacture acetylene by either the partial oxidation of natural gas or as a co-product from the steam cracking of ethylene ... Acetylene produced by either method is used primarily as a closed system industrial intermediate. Minor producers manufacture smaller amounts of acetylene by reacting calcium carbide with water manufactured using the carbide process.

Wholesale and Retail Trade

Ethyne: ACTIVE

When mixed with oxygen in proportions of 40% or more acetylene acts as ... /CNS depressant/.

In gas welding ... the oxyacetylene flame, consisting of a mixture of equal volumes of oxygen and acetylene, has a higher temperature than any other commercially available fuel gas combination ...