International Biodiesel Day takes place on August 10th year. It’s different than Diesel Engine Day, which was celebrated on February 23rd, or National Biodiesel Day, which happened on March 18th. Keeping those dates straight might not be a priority, but choosing the right rubber for parts is critical if you’re an engineer. Otherwise, seals, gaskets, and hoses could swell, degrade, or erode – and damage that’s directly attributable to fuel might not be covered by warranty.
Biodiesel is different from diesel fuel, and there are various biodiesel blends available. This article provides an overview of biodiesel and its effect on rubber compounds, raw rubber that’s mixed with other substances to improve its performance. Compound selection isn’t as simple as asking for “black rubber”, so keep reading to learn more. Elasto Proxy helps manufacturers choose the right rubber for their applications, so contact us for fuel-resistant seals, gaskets, or hoses.
What is Biodiesel Fuel?
Biodiesel is a renewable fuel that’s made from plant oils, animals fats, and recycled restaurant oils and greases. Plant oils come from crops such as soybeans, cottonseed, sunflowers, and corn. Animal fats include beef tallow and pork lard. Restaurant-quality grease or cooking oil (i.e., yellow grease) can be from blended sources. Pure biodiesel is non-toxic and biodegradable, but blends that include petroleum are often used with diesel-powered equipment.
Biodiesel Advantages
The advantages of biodiesel are many. Compared to petroleum diesel fuel, biodiesel can reduce tailpipe soot emissions from older engines that lack modern emissions controls. Biodiesel is also compatible with new technology diesel engines (NTDEs), powerplants with emissions control systems that include diesel oxidation catalysts and particulate filters. In addition, pure biodiesel has significantly lower greenhouse gas emissions than petroleum diesel fuel.
Biodiesel Applications
Biodiesel fuel is used to power a variety of vehicles and equipment. Here are some examples.
- On-road: Semis, tankers, flatbeds, dump trucks, buses, and box trucks
- Off-road: Construction, mining, agricultural, and forestry equipment
- Rail: Locomotives, especially those used by larger, Class I railroads
- Marine: Boats for inland waterways and oceangoing vessels
- Heating systems: Boilers, furnaces, and water heaters.
- Power generation: Generators and gensets
What Are Biodiesel Blends?
Biodiesel can be blended with petroleum diesel fuel or distillates such as No. 1 and No. 2 diesel, military and marine fuels, kerosene, and D396 heating oil. In a biodiesel blend, the number that follows the letter “B” indicates the percentage of biodiesel by volume in 1 gallon or fuel. For example, B20 contains 20% biodiesel by volume. Biodiesel isn’t always blended, however, and B100 indicates the fuel is 100% biodiesel with no petroleum diesel fuels or distillates.
B20
On-road vehicles, off-road vehicles, and locomotives typically use biodiesel in blends of B20 or less. Because B20 is compatible with the same rubber compounds that can withstand petroleum diesel fuel, switching to B20 usually doesn’t require hose, seal, or gasket retrofits. Blends above B20 require equipment modifications, however, including changes to engine seal and gasket materials. It’s also worth noting that different ASTM specs apply depending on the percentage of biodiesel in a fuel.
B100
B100 is a solvent that may loosen or dissolve varnish and sediments left by conventional diesel fuel in tanks and fueling systems. It also gels at higher temperatures than most diesel fuel and heating oil. Importantly, B100 is incompatible with some rubber hoses, seals, and gaskets. B100 may degrade soften, soften, or seep through elastomers, including nitrile compounds.
Elastomer Compatibility with Biodiesel
This table describes the compatibility of various elastomers with biodiesel fuel. Generally (but not always), biodiesel blends of 20% or lower have a much smaller effect on these materials.
Elastomer | Compatibility with Biodiesel |
Buna-N | Not recommended |
Butadiene | Not recommended |
Butyl | Mild effect |
EPDM | Moderate effect |
Fluorocarbon | Satisfactory |
Fluorosilicone | Mild effect |
Natural rubber | Not recommended |
Neoprene | Not recommended |
Perfluoroelastoemr | Satisfactory |
Neoprene/chloroprene | Not recommended |
Nitrile | Not recommended |
Viton® | Satisfactory |
The source of this information is the Biodiesel Handling and Use Guide (Sixth Edition, 2023) from the National Renewable Energy Laboratory (NREL), a federally funded research center sponsored by the U.S. Department of Energy. “If in doubt”, this NREL publication states, “contact the manufacturer for more information about the compatibility of specific material with biodiesel fuels”. It’s also worth picking a manufacturing partner instead of a parts provider.
Happy International Biodiesel Day from Elasto Proxy
Elasto Proxy invites you to join us in celebrating International Diesel Day and hopes that the information in this article will help you to select the right rubber for biodiesel-resistant seals, gaskets, and hoses. If you work for a heavy equipment manufacturer, or if you serve any of the other industries that use biodiesel, contact us for a quote.
