Fuel tank

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A fuel tank (also called a petrol tank or gas tank) is a 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.


The fuel tanks for B-25 bombers B-25 bomb bay gas tanks.jpg
The fuel tanks for B-25 bombers
Fill caps on a BMW automobile for hydrogen (left) and for gasoline (right) fuel tanks Wasserstoffeinfullstutzen eines BMW.jpg
Fill caps on a BMW automobile for hydrogen (left) and for gasoline (right) fuel tanks


Typically, a fuel tank must allow or provide the following:

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.

Fuel tank construction

Fuel tank for the Apollo Lunar Module, 1960s Apollo Lunar Module Fuel Tank.jpg
Fuel tank for the Apollo Lunar Module, 1960s

While most tanks are manufactured, some fuel tanks are still fabricated by metal craftsmen or hand-made in the case of bladder-style tanks. These include custom and restoration tanks for automotive, aircraft, motorcycles, boats 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 are 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 end 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. [1]

In the aerospace industry, the use of Fuel Tank Sealants is a common application for high temperature integral fuel tanks. This provides excellent resistance to fluids such as water, alcohols, synthetic oils and petroleum-based hydraulic fluids. [2]

Automotive fuel tanks

Metal fuel tank for a 1996 Opel Blazer Opel Blazer 1996 Fuel Tank.jpg
Metal fuel tank for a 1996 Opel Blazer
Fuel cell for a 1998-2001 Porsche GT3 Cup racing car Porsche GT3 trunk (front) (6293634244).jpg
Fuel cell for a 1998-2001 Porsche GT3 Cup racing car

Passenger vehicles

A larger fuel-tank results in a greater range for the car between refills, however the weight and space requirements of a larger tank are undesirable, especially in smaller cars. The average fuel tank capacity for cars is 50–60 L (12–16 US gal). [3]

The most common materials for fuel tanks are metal or plastic. Metal (steel or aluminium) fuel tanks are usually built by welding stamped sheetmetal parts together. Plastic fuel tanks usually built using blow molding, which allows more complex shapes to be used.

Reserve tank

Sometimes called the reserve tank is a secondary fuel tank. A light on the instrument panel indicates when the fuel level dips below a certain point in the tank. Some 4×4 vehicles can be fitted with a secondary (or sub-tank) by the dealership.

Ship in a bottle

The ship in a bottle fuel tank is a manufacturing design developed by TI Automotive in Rastatt, Germany wherein all fuel delivery components including the pump, control electronics and most hosing are encased within a blow-molded plastic fuel tank, [4] and named after the traditional ship-in-a-bottle mechanical puzzle. The technique was developed to reduce fuel vapor emissions in response to Partial Zero-Emission Vehicle (PZEV) requirements. [5]

Racing fuel cell

A racing fuel cell has a rigid outer shell and flexible inner lining 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 foam 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). [6]


Layout of a modern airliner's main fuel tanks Jet-liner's main fuel tanks.PNG
Layout of a modern airliner's main fuel tanks

Aircraft typically use three types of fuel tanks: integral, rigid removable, and bladder.

Fuel tanks have been implicated in aviation disasters, being the cause of the accident or worsening it (fuel tank explosion). [8] [ failed verification ] For example:

In some areas, an aircraft's fuel tank is also referred to as an aircraft fuel cell.

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. [11] [12]


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 limits, 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.

Several systems, such as BattleJacket and rubber bladders, have been developed and deployed for use in protecting (from explosion caused by enemy fire) the fuel tanks of military vehicles in conflict zones. [13]

For stationary fuel tanks, an economical way to protect them from hazards like extremes of temperature and vehicle crashes is to bury them. However, buried tanks are difficult to monitor for leaks. This has led to concern about environmental hazards of underground storage tanks.

See also

Related Research Articles

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An inerting system decreases the probability of combustion of flammable materials stored in a confined space. The most common such system is a fuel tank containing a combustible liquid, such as gasoline, diesel fuel, aviation fuel, jet fuel, or rocket propellant. After being fully filled, and during use, there is a space above the fuel, called the ullage, that contains evaporated fuel mixed with air, which contains the oxygen necessary for combustion. Under the right conditions this mixture can ignite. An inerting system replaces the air with a gas that cannot support combustion, such as nitrogen.

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  11. Maciag, Mike (7 June 2007). "Backup Facility to Power Water Works During Outages". Erie Times-News. p. 5B. the Erie Water Works is due to have a 20,000-gallon bulk storage tank and a 5,000-gallon day tank installed to support two diesel-fueled generators serving as backups to the Sommerheim Water Treatment Plant in Erie, Pennsylvania
  12. Comprehensive Everglades Restoration Plan, Section 8, pp 8-3, 8-4, says that small- and medium-sized pumping stations are to be equipped with fuel storage tanks capable of storing seven days capacity, plus "floor-mounted packaged system day tanks" "Section 8" (PDF). Archived from the original (PDF) on 27 September 2007. Retrieved 8 June 2007.
  13. Monitor: Bang but no boom