This is the final installment of a three-part series about ethanol and reviews hazards and firefighter response procedures for ethanol emergencies in transportation and at fixed facilities. Emergency responders have been dealing with spills and fires involving gasoline and diesel fuel for over 100...
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Gasoline has a flash point of -40 degrees Fahrenheit and pure ethanol a flash point of 55°F. The flash point of E85 is -20°F to -4°F. The lower-flash-point gasoline lowers the higher flash point of pure ethanol. At lower temperatures (less than 32°F) E85 vapors are more flammable than gasoline. However, at higher temperatures E85 vapor is less flammable than gasoline because of the higher autoignition temperature of E85. Because of a lower vapor pressure and lower heat of combustion, E85 is generally less of a fire risk than gasoline. Ethanol does have a much wider flammable range than gasoline, which means it will burn in a greater number of concentrations with air than gasoline. It is possible for materials with wide flammable ranges to burn inside containers under the right conditions. (The main point I want to make here is we should not get into a line of thinking that says ethanol or gasoline or blends are any more flammable than the others. All are considered Class 3 Flammable Liquids by the DOT and have a flammability of 3 on the NFPA 704 system. If there is a spill, control ignition sources to prevent a fire from occurring. If spilled fuels are already on fire, understand that different types of foam may be required to extinguish fires involving gasoline, ethanol and blends of each.)
Small fires involving ethanol and its blends can be extinguished with a Class B fire extinguisher (dry chemical). Generally, large fires involving flammable liquids are best contained and extinguished using firefighting foam. There are two basic firefighting foams, one for hydrocarbon fires and one for alcohol or polar-solvent-type fires. Fires involving ethanol/gasoline mixtures with greater than 10% alcohol (E85, for example) should be treated differently than traditional gasoline fires. The DOT recommends emergency responders refer to orange Guide 127 of the ERG when responding to incidents involving fuel mixtures known to contain or potentially contain more than 10% alcohol. Guide 127 specifies the use of alcohol-resistant foam. Ethanol mixtures above 10% are polar/water-miscible flammable liquids and will degrade the effectiveness of non- alcohol-resistant fire-fighting foams.
Denatured alcohol fires (E95) can be extinguished only by using alcohol-resistant (AR) or polar-solvent foams. Conventional aqueous film-forming foam (AFFF) and film-forming fluoroprotein foam (FFFP) will not work on alcohol fires because foams contain water. Water is polar and alcohols are also polar. Alcohol and water mix because they are both polar and the conventional AFFF and other hydrocarbon foams will break down and be ineffective against an alcohol fire.
Gasohol (E10) fires can be extinguished by using conventional foams because E10 contains 90% gasoline. AR-AFFF can also be used to extinguish E10 fires, but increased application rates may be required. AR-type foams must be applied to ethanol fires using Type II gentle-application techniques. Direct application to the surface of the fuel will likely be ineffective unless fuel depth is very shallow. Because ethanol is a polar solvent and mixes readily with water, some thought may be given to dilution of the ethanol or blended mixture. On the surface this seems logical; however, ethanol mixtures with up to 80% water content still burn quite well. Dilution would not be a successful way to extinguish an ethanol fire.
Most responder encounters with ethanol and its blends will occur at the manufacturing facility or in transportation involving an MC/DOT 306/406 atmospheric highway tanker truck or a train of multiple rail cars (see "On The Job — Illinois" on page 52). Ethanol has become the largest-volume hazardous material shipped in the United States. It is also shipped in barges and seagoing tankers. Very little ethanol or its blends are currently transported by pipeline. E98, E95 or denatured ethanol is the most common form transported.
The primary transportation mode for ethanol is the rail car. Trains containing ethanol rail cars may contain large numbers of tank cars with potentially millions of gallons of the flammable liquid in any given train. Ethanol tank cars carry approximately 30,000 gallons each. They are liquid tank cars at atmospheric pressure. Each tank car has a pressure relief valve set to go off at 75 psi overpressure inside the tank. It is, however, possible that pressure may build up inside a tank faster than the relief valve can discharge it. This may result in the tank rupturing violently.
Ethanol blends with gasoline are generally not stored at fixed sites. Denatured ethanol is stored in bulk closed floating roof tanks at storage facilities. The blending process takes place at the loading rack where ethanol and gasoline are blended as they are loaded into tanker trucks. These vehicles carry approximately 9,200 gallons of fuel. Barges may carry from 420,000 gallons to 4.2 million gallons of fuel. Most incidents involving ethanol and its blends with gasoline occur during transportation or transfer of product.