They are often explosive, combustible, poisonous, corrosive, or may offer a combination of all these hazards. Acetylene . 5.2. Pure acetylene is a colourless gas with a pleasant odour; as prepared from calcium carbide it usually contains traces of phosphine that cause an unpleasant garliclike odour. Pure silver acetylide is a heat- and shock-sensitive high explosive. For the exact product composition, please refer to Air Products technical specifications. No water or water-based foams shall be used in such situations. It may react explosively even in the absence of air at elevated pressure and/or temperature. This gas has the widest explosive range of any commonly used gas. The following are the lower explosive limits (LEL) of selected gases. Special hazards arising from the substance or mixture Fire hazard : EXTREMELY FLAMMABLE GAS. • Acetylene regulators clearly indicate pressure at or above 15 psig with red marking on the gauge. Acetylene is a reactive material that poses a fire and explosion hazard. In addition to the acetylene, oxygen is widely used too for gas cutting. Its lower and upper explosive limits in air are 2.5% and 93%, respectively. It forms explosive mixture with the air. If venting or leaking gas catches fire, do not extinguish flames. In … This gives the liquid acetone time to return to its correct place in the porous mass. Highly unstable, acetylene gas, together with air or oxygen easily forms an explosive mixture. A value for t{ is given in Lees (1996) as 10" 5 s. Thus, for a gas explosion, the left-hand side of Eq. Acetylene fires arising from wet calcium carbide inside a building shall be extinguished by using dry-powder extinguishers or carbon dioxide. Storing a flammable gas needs more precautions than regular gas types. Thus, their careful handling and storage is very important. If venting or leaking gas catches fire, do not extinguish flames. Acetylide or Carbide salts are the reason why you should never work acetylene gas with Silver, Copper or Ag/Cu plated utensils: These unstable crystalline explosive compounds form with relative ease by the ionic exchange between acetylene gas and silver or copper salts (reaction outlined below). The decomposition may or may not give rise to explosion, depending on conditions. Acetylene is highly shock sensitive and is a flammable gas that is unstable in certain conditions, which may decompose explosively. Store flammable gas in a cold, closable and dark area is critical. Acetylene gas leaking from a supply tube was ignited by the source flame and a minor explosion occurred, and appears to have damaged both gas supply lines, which led to a second major explosion and fire. A demonstration of the explosive potential of even a small amount of acetylene mixed with the right amount of oxygen. It is a recovered side product in production of ethylene by cracking of hydrocarbons.Approximately 400,000 tonnes were produced by this method in 1983. Failure to do so can cause quality problems with acetone liquid getting into the gas. Explosive character. Acetylene is commonly used in gas cutting. As a result special precautions are required during its production and handling. Pure acetylene is a unique gas with hazards that arise from its high energy bonds and flammability. I made an acetylene explosion in a 25 mL plastic graduated cylinder by dropping calcium carbide pieces into household hydrogen peroxide. Because of the fact that propane, hydrogen, butane, methane, ethylene, acetylene, ammonia, ethane and silane gas are all flammable, and therefore dangerous gas, it is essential to store these gas safely and correctly. Handling Acetylene Cylinders in Fire Situations, for further information. Acetylene reacts with active metals (e.g., copper, silver, and mercury) to form explosive acetylide compounds. Since the 1950s, acetylene has mainly been manufactured by the partial combustion of methane. As the gas is highly combustible when comes in contact with the oxygen, it is recommended to ensure safety measures to avoid accidents. This involved some 6 cu m of acetylene and 18 cu m of nitrous oxide, and caused severe structural damage. Stating that an acetylene cylinder is equivalent to x kg of TNT is little different to saying the same about a car’s petrol tank, a camping gas or propane cylinder, or even your kitchen’s gas hob being equivalent to a certain amount of high explosive. Decomposition is a spontaneous reaction forming hydrogen and carbon … It is very flammable and can bring disastrous accidents if not handled with precautions. Even a small cylinder of the substance can cause a great deal of damage and injury to people and pets. Read Safety Data Sheet before use. A violent, explosive decomposition reaction can occur. Carleton University, Ottawa, Canada. It helps to burn the object at an increased rate. Flammable Gas Incompatibilities & Reactivities Zinc; oxygen & other oxidizing agents such as halogens [Note: Forms explosive acetylide compounds with copper, mercury, silver & brasses (containing more than 66% copper).] Acetylene is commonly used for fueling cutting torches in both general industry and the mining industry. These same prop-erties give acetylene its value as a high temperature cutting and welding gas with a very wide range of applications. At 40 times original pressure, Pex is 60 MPa. Flashback Prevention . Care must be taken to ensure that extinguishing the fire will not increase the hazard of explosion or lack of oxygen by allowing acetylene to accumulate in an unventilated area. Acetylene leaks, no matter how small, can have serious consequences. Extremely flammable gas. Chemical Composition: An acetylene molecule is fabricated by the composition of two carbon atoms and two hydrogen atoms. Acetylene cylinders are to be used and stored only outdoors or in a well ventilated place. For an acetylene gas detonation, the pressure can suddenly increase by a factor of up to 40 (Miller, 1965). However, free acetylene can undergo explosive decomposition when compressed or overheated. per square inch. Order 1947 made under the Explosives Act 1875) defines acetylene gas at pressures of more than 9psi (0.621 BAR) above that of the atmosphere as being an 'explosive' and requires that it may not be held: (a) at pressures in excess of 9psi (0.621 BAR) above that of the atmosphere, except as approved by the Secretary of State, nor Acetylene is a colorless, combustible gas with a distinctive odor. Acetylene gas forms a explosive mixture in contact with air. This paper considers the explosion of an acetylene gas cylinder, which occurred in 1993 in Sydney. Acetylene can be decomposed to its elements with the liberation of heat. The other property of acetylene which you must remember is this: that the flammability range of mixtures of air and acetylene is broader than that of any other fuel gas/air mixture. Fire hazard : EXTREMELY FLAMMABLE GAS. Some tips for safely using and storing acetylene: Always use acetylene in a well vented area, and never in a confined space. Therefore, acetylene stored with acetone solution under 10 atm pressure, acetone absorbed some porous materials for settings safety of the cylinder or suppliers tank. For safety reasons, the acetylene is dissolved in acetone or dimethylformamide in the gas receptacle. Acetylene gas is considered to be a hazardous gas. When mixed with pure oxygen in a cutting torch assembly, an acetylene flame can theoretically reach over 5700°F. If a cylinder has been transported, it must be left to settle in an upright position on arrival. Precautionary Statements: Read label before use. Bulk gas storage has a minimum separation of 3 meters. Acetylene is sparingly soluble in water but readily soluble in an acetone solution. Explosive, fire, blast or projectile hazard. Our member concluded: Flashbacks are commonly caused by a reverse flow of oxygen into the fuel gas hose (or fuel into the oxygen hose), producing an explosive mixture within the hose. For a long time, it was assumed to have the unusual property that on ignition it does not evolve any gas, only decomposing through the reaction: Ag 2 C 2 (s) → 2 Ag (s) + 2 C (s) (In the latter case an effectively unlimited quantity of high explosive.) Ammonia When acetylene is liquefied, compressed, heated, or mixed with air, it becomes highly explosive. Let’s explain that more fully: Acetylene/air mixtures can be ignited when they contain anywhere from 2.5 percent acetylene to 80 percent acetylene. Acetylene is a colorless gas often used as a fuel by plumbers and welders, among other tradespeople, for welding, cutting, and similar processes. Detonation limits have been determined. Flammable vapors may spread from leak, creating an explosive reignition hazard. Acetylene cylinders contain a porous mass and liquid acetone that dissolves the gas. 2.5% vol : Hydrogen . Acetone . extremely flammable gas reacts violently with oxidants and with fluorine or chlorine under influence of light will form explosive mixtures with air; decomposes on heating and increased pressure, causing fire and explosion hazard in the event of a fire involving acetylene, use … 12/12 js ... greater than 15 psig. Compressed Acetylene Gas (215) 898-4453 Office of Environmental Health and Radiation Safety (EHRS) www.ehrs.upenn.edu Rev. Acetylene gas explosion: ‘Hundreds could have died’ DEVASTATION: Above, some of the damage in Wolsingham in the immediate aftermath of the explosion that killed Andy Herd 0 comment A back flow preventive device is used in case of piping the gas. Flammable vapors may spread from leak, creating an explosive reignition hazard. Hazards of Acetylene Gas. When mixed with air, the explosive range is from 2.5% to 82%. This produced acetylene and oxygen at the same time. Asutent crosses to the areeding pes plans, one with green pots and fie atter with yellow patis. See CGA Pamphlet SB-4, Handling Acetylene Cylinders in Fire Situations, for further information. 1.1% vol. Preparation. 2.5% vol : Hexane . acetylene gas is not explosive. 4.0% vol. Every gas has a range in which it can combust or burn. The compressed or liquified unsaturated hydrocarbon like acetylene is a highly explosive gas. per square inch. THE EXPLOSIVE DECOMPOSITION OF ACETYLENE IN PIPELINES By F. W. S. CARVER,† C. M. SMITH, † and G. A. WEBSTER† SYNOPSIS Studhies of the self-decomposition characteristics of acetylene in pipelines have been made as a function of tube diameter, initial pressure, energy of initiation and diluent concentration. Vapors can be ignited by pilot lights, other flames, smoking, sparks, heaters, electrical In welding and metal cutting, acetylene is widely used. Acetylene 74-86-2 100 % Concentration is nominal. This post specifically concentrates on hazards as well as safe storage of compressed acetylene gas cylinders along with some additional information. Its presence in ethylene is usually undesirable because of its explosive character and its ability to poison … According to legislation, this gas should not be compressed freely to more than 20-22 lbs. Acetylene for instance, the gas used in an acetylene torch used to cut metal will combust or explode anywhere from 2.5% concentration all the way up to 100%. (8) is 600 Pa s, which is much less than the right side. 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