Modern fuels require modern fuel hose
Today’s fuel has changed dramatically. Aggressive fuel blends, such as ethanol and biodiesel, have chemical compositions that can damage standard rubber compounds found in general purpose fuel line.
Depending on the mix of fuel in the tank, the rubber in a general purpose fuel hose can quickly deteriorate and fail.
To help reduce cost and the overall failure rate, a fuel line hose must be manufactured with a tube that is compatible with all types of fuels and blends.
ETHANOL
Ethanol is a clean-burning, non-fossil fuel that is produced from a variety of agricultural crops, such as sugarcane and grains. It can be used as an octane-boosting fuel additive or as a stand-alone fuel.
Ethanol fuel mixtures have “E” numbers which describe the percentage of ethanol fuel in the mixture by volume. For example, E85 is 85 percent anhydrous ethanol and 15 percent gasoline.
The most common blends in the United States are E10, E15 and E85.
While these fuel blends help the environment by reducing pollution and dependence on fossil fuels, they have a negative effect on automotive fuel systems.
Several problems have occurred. One is that ethanol degrades general purpose fuel hose, like SAE 30R6 and SAE 30R7, causing it to deteriorate.
Ethanol adversely impacts the hose, as well as rubber seals and other rubber components, causing it to dry, soften, stretch or crack. Plus, degraded hose particles can contaminate and obstruct fuel injectors, which can affect fuel system monitoring sensors and decrease engine efficiency.
VOC EMISSIONS
Another problem is that ethanol blends increase permeation of volatile organic compound (VOC) emissions through common fuel hoses and fuel system components. Permeation emissions are the result of gasoline, either oxygenated or non-oxygenated, “transpiration” – movement from the inside of automotive plastic tanks and hoses to the outside surface of these materials.
The increase of total VOC emissions, which contribute to the formation of ground-level ozone, has so concerned the California Air Resources Board (CARB) that is has prohibited the use of general purpose fuel line hose for fuel.
A number of states now recommend that general purpose fuel line hose not be used and are considering making this illegal.
At the heart of the issue is industry awareness. It is not well understood that if ethanol sits for any length of time, it begins to degrade the hose tubing of SAE 30R6 or SAE 30R7 hose. Over-application of additives may hasten this situation.
There are new hoses available that are designed specifically to be ethanol-resistant and comply with CARB’s low-permeation requirements. By way of example, Gates’ Barricade Fuel Line Hose with GreenShield Technology is CARB-certified and is compatible with U.S. EPA fuels, including gasoline, ethanol blends, methanol, diesel, and biodiesel.
OTHER ISSUES
An additional issue with general purpose fuel line is the high permeation rate allowed per the SAE specification. General purpose fuel line can have permeation rates as high as 600g/m²/day.
Studies have shown that a 2’ section of general purpose fuel hose will permeate (or lose) one gallon of gasoline each year. Gates Barricade has a permeation rate of only 1g/m²/day, which results in a loss of only two tablespoons of fuel per year.
Finally, fuel line hose must have the appropriate working pressure to meet the requirements of the fuel system. More than 98 percent of vehicles in operation include an electronic fuel injection (EFI) system.
Because these fuel injectors spray fuel into the engine under high pressure, a higher working pressure of the fuel line is required.
General purpose fuel line has a working pressure rating of 50 psi, while EFI systems require a fuel line hose with a working pressure rating up to100 psi.
There is a tremendous safety issue with using standard fuel line on an EFI system and this could potentially lead to catastrophic failure and risk of fire. Therefore, fuel injection hoses need to have a working pressure rating which exceeds all OEM requirements for EFI applications.
It is important to note that while the appropriate fuel hose will deliver good performance with today’s fuels, some are designed to handle fuel on the inside only. With in-tank (submersible) applications, fuel also comes in constant contact with the outside hose cover, making it vital to use a hose that’s engineered to be submersible.
For in-tank applications, fuel line must meet or exceed the SAE 30R10 rating, which is the standard for submersible fuel line hose applications.
Mark Kostecki is category manager, fluid products, for Gates Corporation (www.gates.com), a global manufacturer of fluid power products and world’s leading manufacturer of power transmission belts. He has more than 18 years of marketing experience in the automotive aftermarket.
