Find a Security Clearance Job!

Military


AOG Gasoline Tanker

A Gasoline Tanker is a product tanker designed specifically to carry gasoline. A product tanker is designed to carry a variety of liquid products varying from crude oil to clean and dirty petroleum products, acids and other chemicals. The tanks are coated to prevent product contamination and hull corrosion. The ship may have equipment designed for the loading and unloading of specific cargoes.

Gasoline is a hazardous material, and, although used frequently without incident, requires careful attention when handling to avoid serious injury. Gasoline is a lightweight material that flows easily, spreads quickly, and may evaporate completely in a few hours under temperate conditions. It poses a risk of fire and explosion because of its high volatility and flammability, and is more toxic than crude oil. Gasoline is amenable to biodegradation, but the use of dispersants is not appropriate unless the vapors pose a significant human health or safety hazard.

In 1860 German engine inventor Nicholas Otto used ethanol as the fuel in one of his engines. Otto is best known for his development of a modern internal combustion engine (the Otto Cycle) in 1876. In 1896 Henry Ford built his first automobile, the quadricycle, to run on pure ethanol. In 1908 Henry Ford produced the Model T. As a flexible fuel vehicle, it could run on ethanol, gasoline, or a combination of the two. But by the 1920s, gasoline became the motor fuel of choice.

For the first few decades of flight, aircraft engines simply used the same kind of gasoline that powered automobiles. Soon after World War I, the American chemist Thomas Midgely, determined that small quantities of a suitable chemical added to high-grade gasoline might help it burn without knock. After trying a number of additives, he concluded that the best was tetraethyl lead. The US Army Air Corps began experiments with leaded aviation fuel as early as 1922; the Navy adopted it for its carrier-based aircraft in 1926. Leaded gasoline became standard as a high-test fuel.

In the 1930s Major Jimmie Doolittle, already famous in the aviation community as a racing pilot, was head of the aviation fuels section of the Shell Oil Company. At that time, most gas had no more than an 87 octane rating. He pushed for the development of 100-octane fuel (commonly called Aviation Gasoline or AvGas), and the infrastructure needed to produce it in large quantities.

Going in to the Second World War, American combat aircraft and land combat systems were fueled by various grades of gasoline. The development of jet engines, fueled by kersosine blends, led to a substantial reduction in the military's use of AvGas. And over time, the highly flamable gasoline was replaced by safer diesel in tanks and other ground systems.

There are many different types of gasoline: leaded, unleaded, aviation gasolines (avgas), various grades and octane ratings, and various additive contents. Leaded avgas remains available in several grades with differing lead concentrations (e.g. Avgas 100LL). It is used for reciprocating piston engine aircraft (not jet engines). Most avgas is dyed blue or green.

In an internal combustion engine, gasoline is metered in liquid form, through the fuel injectors (or carburetor), and mixed with air and atomized before entering the cylinders. Therefore, it is very important that a fuel's tendency to evaporate is controlled to certain standards. A fuel's ability to vaporize or change from liquid to vapor is referred to as its volatility. In gasoline, the distillation characteristics, along with vapor pressure, define and control starting, warm-up, acceleration, vapor lock, crankcase oil dilution, and, in part, fuel economy and carburetion icing.

Gasoline is a mixture of over 200 petroleum-derived chemicals plus a few synthetic products that are added to improve fuel performance. Gasoline is a generic term used to describe volatile, flammable petroleum fuels used primarily in internal combustion engines to power passenger cars and other types of vehicles, such as buses, trucks, and motorbikes.

Gasoline is a mixture of volatile hydrocarbons suitable for use in a spark-ignited internal combustion engine and having an octane number of at least 60. Octane number is a measure of burn rate, not power as is commonly assumed. Maximum power output is achieved by optimizing the rate at which a fuel burns inside the cylinders of an engine. The octane scale is defined such that pure n-heptane has an octane number of zero and isooctane has an octane number of 100.

Gasolines are most commonly rated based on their Antiknock Index (AKI), a measure of octane quality. The octane is a measure of gasoline's ability to resist knock or auto-ignition. The fuel-air mixture in the cylinder of a spark ignition engine will, under certain conditions, auto-ignite. This pre-firing may cause an audible "ping" or knock and may also cause an engine to continue running when turned off. Loss of power and damage to an engine can occur when knocking is severe and prolonged.

Most gasoline blends are complex solutions (fuels are solutions, not mixtures), containing 50 to 150 components, formulated for burn rate (octane number), volatility (for constant performance in hot and cold weather), and emission control (oxygenated fuels). Gasoline is a highly volatile petroleum product comprised primarily of light hydrocarbons, alkenes, benzene and alkyl substituted benzenes (toluene, xylenes, ethylbenzene). Benzene, toluene, ethylbenzene, and xylene are commonly referred to as BTEX.

Gasoline fuel is a variable mixture of volatile hydrocarbons including paraffins, olefins, cycloparaffins, and aromatic compounds; tetraethyl lead, methanol, and other agents may be added during manufacturing.

There are two primary forms of gasoline: regular (leaded gasoline) and unleaded gasoline. The change from regular gasoline to unleaded gasoline was due to lead accumulation in the environment. By 1960, an estimated 200 million tons of lead went into gasoline annually and much of it escaped from tail pipes into the environment. Lead has been proven to be extremely toxic to the ecosystem and humans. All cars made after 1975 were equipped with catalytic convertors which run on unleaded gas. Unleaded gasoline may contain up to 0.013 g/L lead in the US. Since 1986, leaded gasoline cannot contain more than 0.025 g/L lead US.

Common gasoline additive MTBE is the second most commonly manufactured chemical in the US and also the world; it has different physical chemical characteristics and thus cleanup approaches for groundwater must be different than approaches taken for benzene, toluene, xylenes, and other common gasoline contaminants.

Gasoline is a mixture of approximately 280 different hydrocarbons in the range of C4 to C12; assessing the ecotoxicology of gasoline is tantamount to measuring the toxicity of the water soluble mono-aromatic components, particularly benzene, toluene, ethyl benzene, and xylenes (BTEX). Gasoline and its BTEX components clearly exhibit short-term toxicity effects to a variety of aquatic organisms, especially in closed or flow through systems.

Combustion can result when an ignition source is present and fuel and oxygen are also available. Electrical hazards may also be potential ignition sources when testing devices which dispense flammable products or working near flammable products. Possible sources of ignition include, but are not limited to: open flames or smoking, metal to metal contact which causes sparking (e.g., metal wrench or hammer on a pipe fitting), a running motor, static discharge, worn or faulty electrical wiring, improper grounding, and the wearing of synthetic clothing.

An explosion cannot occur in a tank or any contained location that contains only gasoline. An oxidizer, such as oxygen must be present. The potential for explosion occurs with gasoline at concentrations of 1.1-3.3%. Due to the explosive nature of gasoline, even safety equipment needs to be evaluated for safety.

Flash point combined with vapor volume makes gasoline one of the most hazardous chemicals in common use today. Only two chemicals have a flash point lower than gasoline: ethyl ether and ethyl chloride. A very important reason to maintain the flash point as high as possible is due to the electrostatic hazards in pumping distillate fuels.

The high Vapor Volume of gasoline creates highly flammable vapors which rapidly diffuse throughout storage containers and rooms. Vapor Volume is the number of cubic feet of vapor resulting from the complete evaporation of one gallon of liquid, provides a striking view of the inherent danger of improperly stored gasoline. The vapor volume of gasoline is 24-32 cubic feet at 75 F. Thus, a 1000 cubic foot storage shed, which contains one gallon of vaporized gasoline, can produce an atmosphere containing 2.4-3.2% gasoline vapor. Because the Lower Explosive Limit of gasoline is 1.4%, the storage shed is a clear danger. In fact, current safety practice would forbid entry into this potential death trap.

Flash point is the lowest temperature at which sufficient vapors from a liquid are present that the air/vapor mixture will ignite when exposed to an ignition source. A product with a flash point near or below 100 degrees F is particularly dangerous because exposure to any ignition source, such as a spark from static electricity or a burning cigarette, may set off a fire or explosion. For example, extreme caution should be used when handling and storing gasoline because it has a flash point of -45 to -50 degrees F. Because of the extremely low Flash Point of gasoline, small volume spaces containing gasoline vapors are a problem. Such spaces include gas containers, vessel bilges, storage rooms, garages, and hangars. Vaporized gasoline can produce dangerous atmospheres capable of ignition from various sources: open flames, hot surfaces, sparks from welding/cutting machines, electrical equipment, static electricity.

Flammable limits are the lowest and highest concentrations of vapor or gas in the air that will ignite when exposed to a spark or flame. The Lower Flammable Limit is the LFL (or LEL) and the Upper Flammable Limit is the UFL (or UEL). Products with wide flammable limits (such as ethyl ether, 1.9-36) may ignite either near or far from an ignition source. When considering the explosion hazards, the LFL is the most important. The lower the LFL, the less of a substance needed in the air before it can ignite.



NEWSLETTER
Join the GlobalSecurity.org mailing list


Unconventional Threat podcast - Threats Foreign and Domestic: 'In Episode One of Unconventional Threat, we identify and examine a range of threats, both foreign and domestic, that are endangering the integrity of our democracy'


 
Page last modified: 07-07-2011 12:38:43 ZULU