High Octane Fuel

The compatibility of elastomer materials used in fuel dispensers was assessed for a gasoline standard containing 0, 10, 17, and 25 volume percent of aggressive ethanol. Specimens of fluorocarbon, fluorosilicone, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), silicone rubber, neoprene and polyurethane were immersed in test fuels flowing at a rate of 0.8m/s for 4 weeks at 60oC and then dried for 20h at 60oC. The change in volume, mass and hardness were measured for wet and dried conditions and dynamic mechanical analysis (DMA) was measured for the dry condition only.

This article summarises the compatibility of six elastomers – used in fuel
storage and delivery systems – with test fuels representing gasoline blended
with up to 85% ethanol. Individual coupons were exposed to test fuels for four
weeks to achieve saturation. The change in volume and hardness, when wetted
and after drying, were measured and compared with the original condition.

The Energy Independence and Security Act (EISA) of 2007 was an omnibus energy policy law designed
to move the United States toward greater energy security and independence. A key provision of EISA is
the Renewable Fuel Standard (RFS) which requires the nation to use 36 billion gallons of renewable fuel
in vehicles by 2022. Ethanol is the most widely used renewable fuel, and a significant portion of the
36 billion gallon goal can be achieved by increasing the ethanol in gasoline to 15%. In fact in March
2009, Growth Energy (a coalition of ethanol producers and supporters) requested a waiver from the
Environmental Protection Agency to allow the use of 15% ethanol in gasoline. In anticipation of this
waiver being granted, uncertainties arose as to whether additional fuel ethanol, such as E15 and E20,
would be compatible with legacy and current materials used in standard gasoline fueling hardware. In the
summer of 2008, the U.S. Department of Energy recognized the need to assess the impact of intermediate
blends of ethanol on the fueling infrastructure, specifically located at the fueling station. This research
effort was led by Oak Ridge National Laboratory and the National Renewable Energy Laboratory in
collaboration with Underwriters Laboratories. The DOE program has been co-led and funded by the
Office of the Biomass Program and Vehicle Technologies Program.
The infrastructure material compatibility work has been supported through strong collaborations between
the DOE labs and UL. NREL led the effort to select and test a limited number of new and legacy fueling
dispenser units using 17% ethanol; the actual testing was conducted at UL under subcontract to NREL.
ORNL led the effort to evaluate the impact of intermediate blends of ethanol on a large number of
materials (metals, elastomers, plastics and sealants) representing those typically used in dispenser
infrastructure. The ORNL materials studies are reported herein, but additional work is under way at
ORNL, and additional interpretation of the combined data from ORNL, NREL, and UL is expected in the
near future

The compatibility of selected metals representative of those commonly used in dispensing
systems was evaluated in an aggressive E20 formulation (CE20a) and in synthetic gasoline
(Reference Fuel C) in identical testing to facilitate comparison of results. The testing was
performed at modestly elevated temperature (nominally 60°C) and with constant fluid flow in an
effort to accelerate potential interactions in the screening test.
Based on weight change, the general corrosion of all individual coupons exposed in the vapor
phase above Reference Fuel C and CE20a as well as all coupons immersed in Reference Fuel C
was essentially nil (