CHEMICAL DATA NOTEBOOK SERIES #120: ETHYL ACETATE
BY FRANK L. FIRE
A flammable, volatile, irritating, colorless liquid with a pleasant, fruity odor, ethyl acetate is used as a solvent for coatings, dopes, lacquers, shellacs, varnishes, and other products. It also has several other uses in industry.
Ethyl acetate belongs to a chemical family known as esters, which are the flavors and fragrances of nature. Most have pleasant odors, but several are very foul-smelling. All the fruit and flower fragrances and vegetable, herb, and spice flavors are produced by esters.
Esters are covalently bonded chemical compounds with first names of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, vinyl, and so on in the series of radicals of hydrocarbons and have such last names as formate, acetate, propionate, butyrate, acrylate, methacrylate, and so on in the same series. The shorter-chain esters usually are flammable liquids; the longer-chain (and heavier molecular-weight compounds) progress to combustible liquids and to solids that will melt and produce vapors that burn. The heavier esters that appear in nature often are the basis for folk medicines.
Ethyl acetate has the following properties: a flash point of 248F, an explosive (flammable) range of 2.0 to 11.5 percent in air, an autoignition temperature of 7528F, a specific gravity of 0.902, a molecular weight of 88, a vapor density of 3.04, a boiling point of 1718F, and a freezing point of 21178F. It is soluble in water. Its chemical formula is CH3COOC2H5.
Flammability is ethyl acetate`s major hazard. Its flash point of 248F means at all ambient temperatures in industrial and warehouse conditions, it will generate vapors sufficient to form an explosive mixture with the air near the liquid`s surface. Its ignition temperature of 7528F is easily reachable by all common forms of ignition sources, and its explosive range is sufficiently wide that once the lower explosive limit is reached, it will be very difficult to find concentrations of ethyl acetate above its upper explosive limit. The rather high vapor density of 3.04 means the vapors are 3.04 times as heavy as air. The implication of this very high vapor density is that ethyl acetate vapors will sink to the ground and flow along the lower areas in the terrain and accumulate in low spots and enclosed spaces. These vapors are so heavy that they will also accumulate in any confined areas they happen to enter. Since vapors are fluids, they will flow downhill if undisturbed by wind. Anyone entering such a space without respiratory protection stands a chance of suffering anything from dizziness, drowsiness, headache, narcosis, and nausea to severe irritation of the lungs to unconsciousness and death.
Ethyl acetate has a TLV-TWA (threshold limit value-time weighted average) of 400 ppm (parts per million of air).The vapors of ethyl acetate irritate the skin, eyes, nose, throat, and respiratory system.
Emergency responders can almost always count on the unlucky fact that the vapors of flammable and combustible liquids always seem to move toward a likely ignition source. Once the vapors reach such an ignition source, the vapor/air mixture will explode, flashing back to the original vapor source.
This reaction causes firefighters and other emergency responders tremendous problems. Responders to emergencies involving flammable or combustible liquids expect fire to be the biggest problem they will face. For some reason, even the most experienced firefighters seem to forget that the first reaction that occurs when vapors are ignited is an explosion. The expected fire will follow immediately if any combustible material is left to burn. But it is usually the explosion that causes the most deaths, injuries, and damage. The size and severity of the explosion are determined by the amount of vapor mixed in air (the fuel must be present in the air in quantities within the explosive, or flammable, range).
The amount of vapors in the air is determined by the size of the spill`s surface area, the ambient temperature, the liquid`s temperature, the liquid`s volatility [the speed at which the liquid produces vapors (through evaporation) that will mix with the atmosphere near the surface of the liquid], the configuration of the environment in which the spill has occurred, and the weather conditions.
The higher the volatility, the higher the evaporation rate, and the faster a liquid will produce vapors that will form an ignitable mixture with the air. Ethyl acetate is listed as a “fairly” volatile liquid, which means it will evaporate relatively rapidly.
A stable chemical compound, ethyl acetate will not react rapidly with water; but if standing for a long time, it will hydrolyze (slowly react with water) to form acetic acid and ethyl alcohol. It will also react with strong acids, alkalis, oxidizing agents, and nitrates.
All releases of any appreciable quantity of ethyl acetate should activate the community`s emergency response plan. Since fire and explosion from the released vapor are imminent once the material has been released, the local fire department almost always will assume command of the incident, except when federal, state, or local law names another emergency response organization to command it.
Treat a release of ethyl acetate as any other flammable liquid release: Approach from upwind and uphill; eliminate all possible ignition sources, especially downwind and downhill; remove all nonessential personnel and responders from the danger zone as quickly as possible; and immediately consider evacuating an area surrounding the danger zone. The radius of evacuation depends on the size of the container, the amount of material present, the local terrain, and weather conditions (prevailing and forecasted).
In trying to mitigate the incident, responders must consider ethyl acetate`s chemical and physical properties. Knowing these properties will enable them to predict with at least some small degree of certainty what will occur under different sets of circumstances and in different scenarios. Knowing these hazards may save many lives, including those of the responders.
Water spray or fog may be used to disperse ethyl acetate vapors to avoid a dangerous accumulation. Do not mix the spray or fog with the spilled product. Contain all runoff water.
Emergency containment ponds may be constructed by diking earth, clay, sand, or other absorbent material around the spilled material. If the proper equipment is available, a containment pond may be dug to hold the ethyl acetate. Use nonsparking and compatible (made of a material that will not attack the product) tools and equipment. (Ethyl acetate is relatively noncorrosive.) Also, all electrical equipment must be explosionproof (no flammable vapors may be exposed to electrical sparks generated by electrical motors or batteries). Block catch basins and other entries to the sewer systems. Once the liquid is contained, professional salvage personnel–not emergency responders–may suction it from the containment pond or pit into secure containers.
While professionals are conducting salvage and cleanup operations, the environmental authorities activated by the emergency response plan must determine how much of the soil and other materials must be removed to return the site to an uncontaminated condition. Any liquid ethyl acetate remaining in the pond or pit after the suctioning-out process has been completed may be absorbed by applying cement powder, clay, fly ash, hay, peat, sand, sawdust, soil, straw, or other sorbent material. Handle this material carefully; it contains ethyl acetate liquid and must be disposed of in accordance with federal, state, and local regulations.
Make every effort to prevent ethyl acetate from entering sewers or waterways. If it should enter a sewer system, explosive vapors that will be generated may spread throughout the system, threatening the entire city with an explosion. Of course, the vapors, like the liquid, will flow downgrade, but they will also move upward once the system downgrade is “filled” with vapors. Immediately alert all sewage treatment facilities; care must be exercised throughout the system.
If ethyl acetate enters a waterway, the liquid, since it is only very slightly soluble in water and has a specific gravity of 0.923, will float on the water`s surface. Immediately alert all downstream users of the water; use of the water must be discontinued until the environmental experts have declared it safe for use. Even though ethyl acetate is soluble in water, explosive vapors still can be produced if the water is warmed. The warmer the water, the faster the evolution of explosive vapors. If the waterway has steep banks, a considerable buildup of vapors on the water`s surface will pose a highly dangerous explosion risk near that waterway. If any of the contaminated water enters an industrial facility where it is used to cool hot equipment, the heated water may release enough vapors to cause inhalation problems at the least and explosion possibilities at the worst.
If any low-lying areas are next to the waterway, the contaminated water may be diverted into it instead of being allowed to flow downstream. This technique will allow dissolved product to be removed by aeration techniques. Agitating and spraying the water may remove the dissolved product. This must be done so that vapors do not build up. Some techniques, especially agitation and aeration, will force the dissolved ethyl acetate out of the water, but explosive vapors may be present. Carefully dispose of all materials used as absorbents or adsorbents, since the flammable material will still be present. The environmental authorities on the scene are responsible for monitoring water-purification techniques, which must be carried out by professional personnel trained in those techniques. These same environmental experts will continuously test the water downstream to determine when it can be safely used again. Not only must care be exercised in determining the purity of water used for human consumption, but the water or industrial use must also be certified safe for use.
The rapid pressure rise caused by absorbed heat energy from the fire will subject sealed containers of ethyl acetate exposed to flames or the radiated heat of a fire to catastrophic failure. The failure will be explosive; it could resemble a BLEVE (boiling-liquid, expanding-vapor explosion). Cool such containers with flooding amounts of water delivered by unmanned appliances positioned as far away as possible. Never let yourself be caught between a fire and containers that might explode when exposed to heat.
Any pressure-relief valve present on the heated containers will be venting flammable vapors and almost always will be ignited, adding additional heat energy and danger to the situation. A failure of the container due to the rapid buildup of pressure could produce a BLEVE-like explosion. Regardless of what explosion occurs (and by what mechanism), the results will be disastrous.
If applied properly, water may be used to extinguish burning ethyl acetate. High-pressure water spray may be effective if applied in the same manner as for any other burning flammable liquid. Alcohol-type foam may be used to blanket the burning liquid if it can be applied in the quantities appropriate for the volume of the liquid burning. Dry chemical and carbon dioxide may be used on smaller fires if the proper terrain and atmospheric conditions exist.
PROTECTIVE CLOTHING AND EQUIPMENT
Since the ethyl acetate is an irritant to human skin and eyes, choose all protective clothing and equipment that will prevent the liquid or vapor from contacting the eyes, skin, or respiratory system. Select splashproof chemical goggles and a face shield for eye protection, and positive-pressure self-contained breathing apparatus is a must. Rubber boots, gloves, aprons, and other impervious clothing will offer some protection. If total encapsulating suits should be worn, one reference says butyl rubber, chlorinated polyethylene, nitrile-butadiene rubber, polyvinyl alcohol, polyurethane, and styrene-butadiene rubber offer adequate protection. Consult the manufacturers of total encapsulating suits and ethyl acetate for their recommendations.
Inhalation. Move the victim to fresh air. If breathing has stopped or becomes difficult, administer artificial respiration (mouth-to-mouth resuscitation may expose the first-aid provider to the material in the victim`s mouth or vomit). Immediately obtain medical attention.
Ingestion. If immediate medical attention is not available, give the victim a strong solution of salt water and induce vomiting. Never force an unconscious person to drink anything or to vomit. Call for immediate medical attention while making sure the victim is warm and comfortable.
Skin contact. Remove all contaminated clothing, and wash all affected body areas with large amounts of water. If irritation persists after washing, medical attention is necessary.
Eye contact. Immediately flush the eyes with large amounts of water for 20 minutes, occasionally lifting the eyelids. Immediate medical attention should be provided.
IDENTIFICATION NUMBERS AND RATINGS
(Chemical Abstract Services)
(Standard Transportation Commodity Code)
(Registry of Toxic Effects of Chemical Substances)
(United Nations/North America)
(Chemical Hazard Response Information System)
(U.S. Department of Transportation)
flammable liquid 3
NFPA 704 Rating
(National Fire Protection Association)
(International Maritime Organization)
3.2, flammable liquid
FRANK L. FIRE is the vice president of marketing for Americhem Inc. in Cuyahoga Falls, Ohio. He`s an instructor of hazardous-materials chemistry at the University of Akron as well as an adjunct instructor of haz mats at the National Fire Academy. Fire is the author of The Common Sense Approach to Hazardous Materials and an accompanying study guide, Combustibility of Plastics, and Chemical Data Notebook: A User`s Manual, published by Fire Engineering Books. He is an editorial advisory board member of Fire Engineering.