Fuel tank
Encyclopedia
A fuel tank is safe container for flammable fluids. Though any storage tank
for fuel may be so called, the term is typically applied to part of an engine system in which the fuel
is stored and propelled (fuel pump
) or released (pressurized gas) into an engine
. Fuel tanks range in size and complexity from the small plastic tank of a butane
lighter to the multi-chambered cryogenic
Space Shuttle external tank
.
Plastic (high-density polyethylene HDPE) as a fuel tank material of construction, while functionally viable in the short term, has a long term potential to become saturated as fuels such as diesel and gasoline permeate the HDPE material.
Considering the inertia and kinetic energy of fuel in a plastic tank being transported by a vehicle, environmental stress cracking
is a definite potential. The flammability of fuel makes stress cracking a possible cause of catastrophic failure. Emergencies aside, HDPE plastic is suitable for short term storage of diesel and gasoline. In the U.S., Underwriters Laboratories
approved (UL 142) tanks would be a minimum design consideration.
addressed - such as where the outlet, drain, fluid level indicator, seams, and baffles go. Then the craftsmen must determine the thickness, temper and alloy of the sheet he will use to make the tank. After the sheet is cut to the shapes needed, various pieces are bent to create the basic shell and/or ends and baffles for the tank. Many fuel tanks' baffles (particularly in aircraft and racecars) contain "lightening" holes. These flanged holes serve two purposes, they reduce the weight of the tank while adding strength to the baffles. Toward the ends of construction openings are added for the filler neck, fuel pickup, drain, and fuel-level sending unit. Sometimes these holes are created on the flat shell, other times they are added at the end of the fabrication process. Baffles and ends can be riveted into place. The heads of the rivets are frequently brazed or soldered to prevent tank leaks. Ends can then be hemmed in and soldered, or flanged and brazed (and/or sealed with an epoxy-type sealant) or the ends can be flanged and then welded. Once the soldering, brazing or welding is complete, the fuel tank is leak-tested.
Two technologies are used to make fuel tanks for automobiles:
Modern cars often feature remote opening of the fuel tank fuel filler flap using an electric motor
or cable release. For both convenience and security, many modern fuel tanks cannot be opened by hand or otherwise from the outside of the car.
is a secondary fuel tank (in many cars/bikes it contains around 15% of the capacity of the primary tank) these are more commonly found on bikes, older cars (some without fuel gauge) and vehicles designed for long distance or special use. A light on the instrument panel indicates when the fuel level dips below a certain point in the tank. There is no current standard, although some efforts are made to collect this data for all automobiles.
In vehicles modified for endurance the primary tank (the one that comes with the car) is made into a reserve tank and a larger one installed. Some 4x4 vehicles can be fitted with a secondary (or sub-tank) by the dealership.
core to prevent explosion of vapor in the empty portion of the tank and to minimize sloshing of fuel during competition that may unbalance the vehicle or cause inadequate fuel delivery to the motor (fuel starvation
).
For safety considerations, in modern cars the fuel tank is usually located ahead of the rear axle, out of the crumple zone
s of the car.
Automobiles such as the Ford Pinto or the models that still use the Ford Panther platform
(Ford Crown Victoria, Lincoln Town Car, and Mercury Grand Marquis) are notorious for having the fuel tank behind the rear axle. Since 1980 new Ford models corrected this problem and had the fuel tank in front of the rear axle.
General Motors
1973-1987 C/K pickup trucks have the fuel tank located outside the frame. According to the Center for Auto Safety
this creates a fire hazard. In automotive applications, improper placement of the fuel tank has led to increased probability of fire in collisions. Circa 1990, General Motors
faced over a hundred product liability
lawsuits related to fires allegedly caused by GM's decision to place the fuel tanks in its pickup truck
s outside the protection of the vehicle's frame http://www.rolanddarby.com/br_sidesaddle.html. In 1993, reportage on this matter for NBC News
created a scandal over vehicles rigged to catch fire for the television camera.
Ford's Pinto
also sparked controversy for putting the fuel tank in a poorly reinforced area which can cause deadly fires and explosions if the car got into a rear end collision, costing Ford US$
125 million.
Fuel tanks have been implicated in aviation disasters
, being the cause of the accident or worsening it (fuel tank explosion
). For example:
s, and thus cannot burn even if an ignition source were present (which is rare).
Bunded oil tanks are used for safely storing domestic heating oil and other hazardous materials. Bunding
is often required by insurance companies, rather than single skinned oil storage tanks.
Storage tank
A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs , and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, American English and moderately common in British...
for fuel may be so called, the term is typically applied to part of an engine system in which the fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
is stored and propelled (fuel pump
Fuel pump
A fuel pump is a frequently essential component on a car or other internal combustion engined device. Many engines do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine...
) or released (pressurized gas) into an engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
. Fuel tanks range in size and complexity from the small plastic tank of a butane
Butane
Butane is a gas with the formula C4H10 that is an alkane with four carbon atoms. The term may refer to any of two structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, butane refers only to the unbranched n-butane isomer; the other one being called "methylpropane" or...
lighter to the multi-chambered cryogenic
Cryogenics
In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...
Space Shuttle external tank
Space Shuttle external tank
A Space Shuttle External Tank is the component of the Space Shuttle launch vehicle that contains the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplies the fuel and oxidizer under pressure to the three Space Shuttle Main Engines in the orbiter...
.
Uses
Typically, a fuel tank must allow or provide the following:- Storage of fuel: the system must contain a given quantity of fuel and must avoid leakage and limit evaporative emissions
- Filling: the fuel tank must be filled in a secure way, without sparks
- Provide a method for determining level of fuel in tank, GaugingFuel gaugeA fuel gauge is an instrument used to indicate the level of fuel contained in a tank. Commonly used in cars, these may also be used for any tank including underground storage tanks.As used in cars, the gauge consists of two parts:...
(the remaining quantity of fuel in the tank must be measured or evaluated) - Venting (if over-pressure is not allowed, the fuel vapors must be managed through valves)
- Feeding of the engineEngineAn engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
(through a pump)
- Anticipate potentials for damage and provide safe survival potential.
Plastic (high-density polyethylene HDPE) as a fuel tank material of construction, while functionally viable in the short term, has a long term potential to become saturated as fuels such as diesel and gasoline permeate the HDPE material.
Considering the inertia and kinetic energy of fuel in a plastic tank being transported by a vehicle, environmental stress cracking
Environmental stress cracking
Environmental Stress Cracking is one of the most common causes of unexpected brittle failure of thermoplastic polymers known at present. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.ESC and polymer resistance to ESC have been studied...
is a definite potential. The flammability of fuel makes stress cracking a possible cause of catastrophic failure. Emergencies aside, HDPE plastic is suitable for short term storage of diesel and gasoline. In the U.S., Underwriters Laboratories
Underwriters Laboratories
Underwriters Laboratories Inc. is an independent product safety certification organization. Established in 1894, the company has its headquarters in Northbrook, Illinois. UL develops standards and test procedures for products, materials, components, assemblies, tools and equipment, chiefly dealing...
approved (UL 142) tanks would be a minimum design consideration.
Fuel tank construction
While most tanks are manufactured, some fuel tanks are still fabricated by metal craftsmen. These include custom and restoration tanks for automotive,aircraft, motorcycles, and even tractors. Construction of fuel tanks follows a series of specific steps. The craftsman generally creates a mockup to determine the accurate size and shape of the tank, usually out of foam board. Next, design issues that affect the structure of the tank areaddressed - such as where the outlet, drain, fluid level indicator, seams, and baffles go. Then the craftsmen must determine the thickness, temper and alloy of the sheet he will use to make the tank. After the sheet is cut to the shapes needed, various pieces are bent to create the basic shell and/or ends and baffles for the tank. Many fuel tanks' baffles (particularly in aircraft and racecars) contain "lightening" holes. These flanged holes serve two purposes, they reduce the weight of the tank while adding strength to the baffles. Toward the ends of construction openings are added for the filler neck, fuel pickup, drain, and fuel-level sending unit. Sometimes these holes are created on the flat shell, other times they are added at the end of the fabrication process. Baffles and ends can be riveted into place. The heads of the rivets are frequently brazed or soldered to prevent tank leaks. Ends can then be hemmed in and soldered, or flanged and brazed (and/or sealed with an epoxy-type sealant) or the ends can be flanged and then welded. Once the soldering, brazing or welding is complete, the fuel tank is leak-tested.
Automotive Fuel Tanks
For each new vehicle a specific fuel system is developed, to optimize the use of available space. Moreover, for one car model, different fuel system architectures are developed, depending on the type of the car, the type of fuel (gasoline or diesel), nozzle models, and region.Two technologies are used to make fuel tanks for automobiles:
- Plastic high-density polyethylene (HDPE) fuel tanks made by blow moldingBlow moldingBlow molding is a manufacturing process by which hollow plastic parts are formed. In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and stretch blow molding. The blow molding process begins with melting down the plastic and forming it into a...
. This technology is increasingly used as it now shows its capacity to obtain very low emissions of fuel (see Partial zero-emissions vehiclePartial zero-emissions vehicleA Partial Zero Emissions Vehicle is a vehicle that has zero evaporative emissions from its fuel system, has a 15-year warranty on its emission-control components, and meets SULEV tailpipe-emission standards....
). HDPE can also take complex shapes, allowing the tank to be mounted directly over the rear axle, saving space and improving crash safety. Initially there were concerns over the low fracture toughnessFracture toughnessIn materials science, fracture toughness is a property which describes the ability of a material containing a crack to resist fracture, and is one of the most important properties of any material for virtually all design applications. The fracture toughness of a material is determined from the...
of HDPE, when compared to steel or aluminum. Concern for safety and long term ability to function should be considered and monitored.
- Metal (steelSteelSteel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
or aluminumAluminiumAluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
) fuel tanks welded from stamped sheets. Although this technology is very good in limiting fuel emissions, it tends to be less competitive and thus less on the market.
Modern cars often feature remote opening of the fuel tank fuel filler flap using an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
or cable release. For both convenience and security, many modern fuel tanks cannot be opened by hand or otherwise from the outside of the car.
Reserve tank
Sometimes called the reserve tankFuel reserve
In motorcycles and cars, fuel reserve is the extra fuel reserved by the manufacturer in the fuel tank of a car or motorcycle before the main fuel capacity runs out....
is a secondary fuel tank (in many cars/bikes it contains around 15% of the capacity of the primary tank) these are more commonly found on bikes, older cars (some without fuel gauge) and vehicles designed for long distance or special use. A light on the instrument panel indicates when the fuel level dips below a certain point in the tank. There is no current standard, although some efforts are made to collect this data for all automobiles.
In vehicles modified for endurance the primary tank (the one that comes with the car) is made into a reserve tank and a larger one installed. Some 4x4 vehicles can be fitted with a secondary (or sub-tank) by the dealership.
Racing fuel cell
A racing fuel cell has a flexible inner liner to minimize the potential for punctures in the event of a collision or other mishap resulting in serious damage to the vehicle. It is filled with an open-cell foamBallistic foam
Ballistic foam is a foam that sets hard. It is widely used in the manufacture and repair of aircraft to form a light but strong filler for aircraft wings. The foam is used to surround aircraft fuel tanks to reduce the chance of fires caused by the penetration of incendiary projectiles....
core to prevent explosion of vapor in the empty portion of the tank and to minimize sloshing of fuel during competition that may unbalance the vehicle or cause inadequate fuel delivery to the motor (fuel starvation
Fuel Starvation
Fuel starvation and fuel exhaustion are problems that can affect internal combustion engines fuelled by either diesel, kerosene, petroleum or any other combustible liquid or gas. If no fuel is available for an engine to burn, it cannot function...
).
Placement and safety
Crumple zone
The crumple zone is a structural feature mainly of automobiles. Crumple zones have also been incorporated into railcars in recent years.They are designed to absorb the energy from the impact during an accident by controlled deformation. This energy is much higher than is commonly recognized...
s of the car.
Automobiles such as the Ford Pinto or the models that still use the Ford Panther platform
Ford Panther platform
The Ford Panther platform is an automobile platform that was used by Ford Motor Company for full-size, rear-wheel drive sedans. Introduced in late 1978 for the 1979 model year, it was progressively updated over 33 years of production. In September 2011, the last car produced on the platform was...
(Ford Crown Victoria, Lincoln Town Car, and Mercury Grand Marquis) are notorious for having the fuel tank behind the rear axle. Since 1980 new Ford models corrected this problem and had the fuel tank in front of the rear axle.
General Motors
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
1973-1987 C/K pickup trucks have the fuel tank located outside the frame. According to the Center for Auto Safety
Center for Auto Safety
The Center for Auto Safety was founded in 1970 by Consumers Union and Ralph Nader as a Washington, D.C.-based lobbying group focused on the United States automotive industry.- Accomplishments :...
this creates a fire hazard. In automotive applications, improper placement of the fuel tank has led to increased probability of fire in collisions. Circa 1990, General Motors
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
faced over a hundred product liability
Product liability
Product liability is the area of law in which manufacturers, distributors, suppliers, retailers, and others who make products available to the public are held responsible for the injuries those products cause...
lawsuits related to fires allegedly caused by GM's decision to place the fuel tanks in its pickup truck
Pickup truck
A pickup truck is a light motor vehicle with an open-top rear cargo area .-Definition:...
s outside the protection of the vehicle's frame http://www.rolanddarby.com/br_sidesaddle.html. In 1993, reportage on this matter for NBC News
NBC News
NBC News is the news division of American television network NBC. It first started broadcasting in February 21, 1940. NBC Nightly News has aired from Studio 3B, located on floors 3 of the NBC Studios is the headquarters of the GE Building forms the centerpiece of 30th Rockefeller Center it is...
created a scandal over vehicles rigged to catch fire for the television camera.
Ford's Pinto
Ford Pinto
The Ford Pinto is a subcompact car produced by the Ford Motor Company for the model years 1971–1980. The car's name derives from the Pinto horse. Initially offered as a two-door sedan, Ford offered "Runabout" hatchback and wagon models the following year, competing in the U.S. market with the AMC...
also sparked controversy for putting the fuel tank in a poorly reinforced area which can cause deadly fires and explosions if the car got into a rear end collision, costing Ford US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
125 million.
Aircraft
Aircraft typically use three types of fuel tanks: integral, rigid removable, and bladder.- Integral tanks are areas inside the aircraft structure that have been sealed to allow fuel storage. An example of this type is the "wet wing" commonly used in larger aircraft. Since these tanks are part of the aircraft structure, they cannot be removed for service or inspection. Inspection panels must be provided to allow internal inspection, repair, and overall servicing of the tank. Most large transport aircraft use this system, storing fuel in the wings, belly, and sometimes tail of the airplane.
- Rigid removable tanks are installed in a compartment designed to accommodate the tank. They are typically of metal construction, and may be removed for inspection, replacement, or repair. The aircraft does not rely on the tank for structural integrity. These tanks are commonly found in smaller general aviation aircraft, such as the Cessna 172Cessna 172The Cessna 172 Skyhawk is a four-seat, single-engine, high-wing fixed-wing aircraft. First flown in 1955 and still in production, more Cessna 172s have been built than any other aircraft.-Design and development:...
. - Bladder tanks are reinforced rubberized bags installed in a section of aircraft structure designed to accommodate the weight of the fuel. The bladder is rolled up and installed into the compartment through the fuel filler neck or access panel, and is secured by means of metal buttons or snaps inside the compartment. Many high-performance light aircraft and some smaller turboprops use bladder tanks. One major down-side to this type of tank is the tendency for materials to work hardenWork hardeningWork hardening, also known as strain hardening or cold working, is the strengthening of a metal by plastic deformation. This strengthening occurs because of dislocation movements within the crystal structure of the material. Any material with a reasonably high melting point such as metals and...
through extensive use making them brittle causing cracks. One major plus side is the ability to utilise as much of the aircraft as possible to store fuel. - Combat aircraft generally use self-sealing fuel tankSelf-sealing fuel tankIn aviation, self-sealing fuel tank is a fuel tank technology in wide use since World War II that prevents fuel tanks primarily on aircraft from leaking fuel and igniting after being damaged by enemy fire....
s.
Fuel tanks have been implicated in aviation disasters
Aviation accidents and incidents
An aviation accident is defined in the Convention on International Civil Aviation Annex 13 as an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, in which a...
, being the cause of the accident or worsening it (fuel tank explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
). For example:
- The official explanation for the explosion and subsequent crash of TWA Flight 800TWA Flight 800Trans World Airlines Flight 800 , a Boeing 747-131, exploded and crashed into the Atlantic Ocean near East Moriches, New York, on July 17, 1996, at about 20:31 EDT, 12 minutes after takeoff, killing all 230 persons on board. At the time, it was the second-deadliest U.S...
is that an explosive fuel/air mixture was created in one of the aircraft's fuel tanks. Faulty wiring then provided an ignition source within the tank, destroying the airliner. While the accuracy of the official findings is still questioned in this case, similar explosions have occurred in other aircraft. It is possible to reduce the chance of fuel tank explosions by a fuel tank inerting systemInerting systemAn inerting system increases the safety of a fuel tank, ball mill, or other sealed or closed-in tank that contains highly flammable material. Inert in scientific terminology means ‘not readily reactive with other elements; forming no chemical compounds or something that is not chemically...
or fire-fighting foam in the tanks. - Burning fuel can explode or set fire to the same airplane or adjacent objects and people. In the 1960 Munich Convair 340 crash, a transport crashed into a major street. Burning fuel set fire to a tramcar. All 20 people aboard the plane and 32 passengers of the tram died.
Water supply
Water supply systems can have primary or backup power supplied by diesel-fueled generators fed by a small "day tank" and a much larger bulk storage fuel tank.Safety
Proper design and construction of a fuel tank play a major role in the safety of the system of which the tank is a part. In most cases intact fuel tanks are very safe, as the tank is full of fuel vapour/air mixture that is well above the flammability limitFlammability limit
Flammability limits, also called flammable limits, give the proportion of combustible gases in a mixture, between which limits this mixture is flammable. Gas mixtures consisting of combustible, oxidizing, and inert gases are only flammable under certain conditions. The lower flammable limit ...
s, and thus cannot burn even if an ignition source were present (which is rare).
Bunded oil tanks are used for safely storing domestic heating oil and other hazardous materials. Bunding
Bunding
Bunding, also called a bund wall, is the area within a structure designed to prevent inundation or breaches of various types.-Liquid containment:...
is often required by insurance companies, rather than single skinned oil storage tanks.
See also
- ElectrificationElectrificationElectrification originally referred to the build out of the electrical generating and distribution systems which occurred in the United States, England and other countries from the mid 1880's until around 1940 and is in progress in developing countries. This also included the change over from line...
- ExplosionExplosionAn explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
- Fast fuel systemFast fuel systemA Fast fuel system allows speedy refuelling of vehicles. Most large earthmoving and mining vehicles with diesel fuel tanks over are equipped with fast refueling systems. Fast refueling systems utilize an automatic shut off fuel nozzle, receiver and level control device...
- Fuel filterFuel filterA fuel filter is a filter in the fuel line that screens out dirt and rust particles from the fuel, normally made into cartridges containing a filter paper. They are found in most internal combustion engines....
- Fuel leak
- Fuel lineFuel lineA fuel line is a hose used to bring fuel from one point in a vehicle to another or from a storage tank to a vehicle. It is commonly made of reinforced rubber to prevent splitting and kinking....
- Fuel pumpFuel pumpA fuel pump is a frequently essential component on a car or other internal combustion engined device. Many engines do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine...
- JettisonJettisonJettison may refer to:* A verb meaning to throw or eject from a ship, aircraft or vehicle; or discard or abandon; see marine debris* Jettison , a Chicago-based indie record label* Jettison , a punk band from the 1980s...
- Fuel bladderFuel bladderFuel bladders or fuel storage bladders are collapsible, flexible storage bladders that provide temporary or long term storage for industrial liquids . These pillow shaped tanks are designed for large volume liquid transport, industrial chemicals, potable water, sludge, and fuel storage...
External links
- Reduction of Fuel Tank Flammability in Transport Category Airplanes (U.S. Environmental Protection AgencyUnited States Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
). - Fuel tank harmonization (Aviation Rulemaking Advisory Committee)
- U.S. Unveils New Rule On Airplane Fuel Tanks, by United States Department of TransportationUnited States Department of TransportationThe United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...
.