Fuel tank
From Wikipedia, the free encyclopedia
A fuel tank is the part of an engine system in which the fuel is stored and released into the 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.
Typically, a fuel tank must allow:
- Filling (the fuel tank must be filled in a secure way)
- Storage of fuel (the system must contain a given quantity of fuel and must avoid leakage and limit evaporative emissions)
- Gauging (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 engine (through a pump)
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[edit] Automotive
For each new vehicle a specific fuel system has to be developed, as they must optimize the empty space left by the car architecture.
Moreover, for one car model, different versions of fuel system architectures have to be developed with more or less components, depending on the type of the car, the type of fuel (gasoline or diesel), nozzle models and the region where the car will be circulating.
Two technologies are used to make fuel tanks for automobiles:
- Plastic High density polyethylene fuel tanks produced through blow molding. This technology is increasingly used as it now shows its capacity to obtain very low emissions of fuel (see Partial zero-emissions vehicle).
- Metal (steel or aluminium) fuel tanks obtained by welding of stamped sheets. Although this technology is very good in limiting fuel emissions, it tends to be less competitive and thus less on the market.
[edit] Central locking
Cars generally includes fuel tank filler flap (also called fuel filler cap) integrated in central locking.
[edit] Remote opening
Modern cars includes remote opening of the fuel tank fuel filler flap using an electric motor. Some expensive cars even have fuel tanks that cannot be opened by hand or by any way from the outside of the car.
[edit] Reserve Tank
Sometimes called the reserve tank, a light on the instrument panel of autos typically illuminates 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. Are you on E?
[edit] 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 and/or 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 172.
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.
Fuel tanks have also been implicated in aviation disasters. For example, the official explanation for the explosion and subsequent crash of TWA Flight 800 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 system.
[edit] Safety
The proper design and construction of a fuel tank plays a major role in the safety of the system of which the tank is a part.
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 lawsuits related to fires allegedly caused by GM's decision to place the fuel tanks in its pickup trucks outside the protection of the vehicle's frame [1]. In 1993, as one of these lawsuits resulted in a US$101 million judgement against GM (later overturned), the television show Dateline NBC created its own controversy by staging an example of the failures. When it was discovered that Dateline's consultants had rigged the truck with incendiary devices in order to guarantee a fire, GM filed a defamation suit, and several NBC employees were fired.
