Fuel tanks are an integral part of any vehicle, serving as a storage container for the fuel that powers the engine. However, fuel tanks can also pose a safety risk if not properly designed and maintained. One important feature of fuel tanks that helps to mitigate these risks is a venting system. In this article, we will explore the reasons why fuel tanks need to be vented, the dangers of unvented tanks, and the different types of vents that are used. By understanding the role of fuel tank vents, we can better appreciate the importance of proper design and maintenance in ensuring the safety of vehicles and their passengers.
The dangers of unvented fuel tanks
Unvented fuel tanks can pose a serious risk to the safety of a vehicle and its passengers. One of the main dangers of unvented tanks is the risk of deformity or tank rupture. As fuel is consumed from the tank, a vacuum is created which can cause the tank to collapse. This can lead to damage to the tank itself and potentially even cause a fuel leak. In addition, if the tank is not properly vented, pressure can build up inside the tank as the fuel expands due to changes in temperature. This can cause the tank to rupture, posing a serious hazard to the vehicle and anyone nearby.
When Tank Aren’t vented Properly
One example of a time when a fuel tank was not properly vented occurred in the 1980s, when several General Motors pickup trucks were recalled due to a defect in the fuel tank design. The trucks in question had fuel tanks that were in the cab of the vehicle, beneath the rear seats. These tanks were not properly vented, which resulted in a few incidents where the tanks ruptured or leaked, posing a serious fire hazard. In response to this issue, General Motors recalled over 3 million pickup trucks and implemented a design change to the fuel tank venting system to prevent future incidents. This incident highlights the importance of proper fuel tank venting in ensuring the safety of vehicles and their passengers.
The role of vents in fuel tank safety
Fuel tank vents are designed to prevent the dangers associated with unvented tanks. They allow pressure to be released from the tank, preventing the risk of explosion or rupture. In addition, vents can help to prevent fuel spills or leaks by maintaining a certain level of vacuum in the tank. This can help to prevent fuel from being forced out of the tank due to changes in pressure or temperature. In this way, fuel tank vents play a crucial role in ensuring the safety of vehicles and their passengers.
It’s important to note that fuel tanks can be vented in a variety of ways, and the specific design of a fuel tank venting system will depend on the size and type of the tank, as well as the intended use of the vehicle. In general, fuel tank vents are designed to allow air to flow in and out of the tank as needed, to prevent the build-up of pressure or vacuum that can lead to explosions, ruptures, or spills. To ensure the safety of their vehicles, it is important for manufacturers to design and maintain fuel tank venting systems in accordance with relevant safety guidelines and regulations, such as the Australian Standard, AS1940 The storage and handling of flammable and combustible liquids (AS1940).
Filtered vs Unfiltered tank vents
Filtered fuel tank vents and unfiltered fuel tank vents are different types of vents that are designed to meet different needs.
Unfiltered fuel tank vents are simple vents that allow air to flow in and out of the tank without any kind of filtration or screening. These vents are typically used in environments where the risk of contamination is low, or where the fuel being used is already treated to prevent contamination. Unfiltered vents are generally low maintenance and easy to install, making them a cost-effective option for many applications.
Filtered fuel tank vents, on the other hand, are designed to protect fuel systems from contamination by filtering out particles and other contaminants from the air that flows in and out of the tank. These vents may use a variety of filtration media, such as paper or foam, to capture particles and prevent them from entering the fuel system. Filtered vents are typically used in environments where the risk of contamination is high, such as in heavy equipment that operates in dusty or dirty conditions. The main benefit of filtered vents is that they can help to extend the service life of fuel filters and reduce the risk of equipment downtime due to blocked filters.
In general, the choice between filtered and unfiltered fuel tank vents will depend on the specific needs of the application and the level of protection required against contamination. It’s important to consider the operating environment and the potential risks of contamination when selecting a fuel tank vent.
Types of fuel tank vents
There are two main types of fuel tank vents: passive vents and active vents.
Passive
Passive vents are simple devices that allow air to flow in and out of the tank as needed, without the need for any external power source. These vents are typically located at the highest point of the tank and rely on the difference in atmospheric pressure to function. Passive vents are relatively low maintenance and are commonly used in small fuel tanks or in tanks that do not experience significant changes in temperature or pressure.
Passive fuel tank vents may use a variety of mechanisms to regulate the flow of air, such as a simple hole in the tank, a one-way valve, or a flapper valve. The specific design of the vent will depend on the size and type of the tank, as well as the intended use of the vehicle.
Active
Active vents, on the other hand, use a powered mechanism to control the flow of air in and out of the tank. These vents are often used in larger fuel tanks or in tanks that experience significant temperature or pressure changes. Active vents may be controlled by a pressure or temperature sensor, which activates the venting mechanism when a certain threshold is reached. Alternatively, active vents may be manually activated by the user, using a switch or other control.
There are several different types of active fuel tank vents, including mechanical vents, diaphragm vents, and pneumatic vents. Mechanical vents use a motor or other mechanical device to open and close a valve or flapper, regulating the flow of air into and out of the tank. Diaphragm vents use a flexible membrane to control the flow of air, while pneumatic vents use pressurized air to open and close a valve or flapper.
Active fuel tank vents offer more precise control over the venting process and can be customised to suit the specific needs of the vehicle. However, they may require more maintenance and may be more complex to install and repair compared to passive vents.
Remote Tank Breather
A remote tank breather is a type of fuel tank vent that is located remotely from the tank itself, rather than being directly attached to the tank. It can provide several benefits in terms of safety, performance, and convenience, making it an appealing option for many fuel system applications. It is generally accepted that having a properly designed and maintained fuel tank venting system, including a remote tank breather if appropriate, can help to prevent accidents and improve the overall safety of a vehicle.
Fuel tank explosions and ruptures can be serious hazards, and proper venting is an important safety feature that can help to prevent these types of incidents. By allowing pressure to be released from the tank and preventing the build-up of vacuum, fuel tank vents can help to prevent explosions, ruptures, and spills. A remote tank breather can provide additional benefits by separating the breather from the tank, reducing the risk of fire or explosion in the event of a fuel leak. A few of the benefits to using a remote tank breather include:
Improved air circulation
By locating the breather away from the tank, it is easier to ensure good air circulation around the tank, which can help to prevent the build-up of heat or pressure that can lead to explosions or ruptures.
Enhanced safety
By separating the breather from the tank, there is less risk of fire or explosion in the event of a fuel spill or leak. This can help to improve the overall safety of the vehicle and its occupants.
Increased flexibility
A remote tank breather can be in a more convenient or easily accessible location, making it easier to service or repair if necessary.
Enhanced fuel system performance
A remote tank breather can help to improve the performance of the fuel system by reducing the risk of contamination and ensuring a consistent flow of air into and out of the tank.
Venting Fuel Tanks
Fuel tank vents are an essential safety feature that helps to prevent the dangers associated with unvented tanks. By allowing pressure to be released and maintaining a certain level of vacuum, fuel tank vents help to prevent explosions, ruptures, and spills. Whether passive or active, fuel tank vents play a crucial role in ensuring the safety of vehicles and their passengers.
Banlaw’s diesel fuel tank vent system is designed to prevent spills and leaks by sealing the tank when it is full. The vent mechanism is also able to manage flow rates to match the refuelling system’s shut-off level. When the tank is full, a small amount of pressure is released through the vent, allowing the tank to return to atmospheric pressure quickly. Banlaw’s vents come in three variations: unfiltered, filtered, and fine-filtered. There is also an option for a remote tank breather. The filtered tank vent is particularly useful for protecting diesel fuel systems in heavy equipment that operate in dusty environments. This vent comes with a serviceable air filter that prevents particles from entering the tank and fuel system, extending the service life of OEM fuel filters, and reducing the risk of equipment downtime due to blocked filters.
