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Technical Reference
Fuel Filtration - Biodiesel Fuel

How would an operator know if a fuel What is a recommended best practice to
system is compatible with the biodiesel avoid biodiesel related fuel problems?
blend being used? The vendor and fleet manager should establish a
Before switching to a biodiesel blend it is best to contact contractual agreement to ensure product quality on a
the Original Equipment Manufacturer (OEM) to make sure consistent basis. Ensure that the fuel you purchase meets
the desired level of biodiesel will not void the warranty. To industry standards such as the ASTM specifications D6751
determine the compatibility operators can run several tests for B100, D7647 for B6 through B20 and D975 for petroleum
on a particular fuel system and the biodiesel blend being diesel, and that it is properly blended to the predefined
used including the following: biodiesel blend target upon receipt. Choose biodiesel
marketers and producers that have attained
Cetane Number – Measures the ignitability National Biodiesel Board BQ-9000 quality program
or ignition quality of the fuel. Biodiesel has a accreditation. If you cannot source fuel from a BQ-9000
higher cetane value which can affect the engine producer/marketer, the next best thing is to verify with
performance. your supplier that each load of fuel meets all ASTM
specifications.
Volatility – Measures the tendency for a fluid to
evaporate. Diesel fuel has a low volatility and the Retain a one-quart sample of fuel. Look at a sample of the
fuel system is very tolerant to a wide range of fuel in a clear mason jar. The fuel should be clear and bright.
volatilities. Biodiesel does have a higher volatility
which if measure beyond the acceptable range could Save this sample until the next load of fuel is received.
lead to increased engine deposits. Discard the sample by adding it to the fuel tank.
Viscosity – Measure how well the fluid flows; this Is there a shelf life for biodiesel fuel?
value is very important for injector systems because
it can affect the spray pattern out of the injector. As with any ULSD, biodiesel has a shelf life of 6 months
Biodiesel can have a much wider range of viscosities to avoid microbial growth and product degradation. With
so it is best to test to make sure it is meeting the proper housekeeping and additives, the shelf life
specifications. can be extended. Consult your fuel supplier for proper
recommendations and testing. Stability additives may be
Low Temperature Operability – Measures the cold needed if fuel is to be stored for longer than six months.
weather properties of the fuel and its ability to flow Biodiesel is less stable than petroleum fuels. Exposure to
at cold temperatures. Biodiesel is more vulnerable to air, heat, light, water and some metals are contributing
gelling at higher temperatures than petroleum based factors that will cause it to degrade. A common symptom
fuels. encountered with degraded fuel is plugged filters. With

Lubricity – This test measures the wear caused the proper housekeeping and additives, the shelf life
by friction between metal parts. Fuel system can be extended. Consult your fuel supplier for proper
components are lubricated by the fuel itself. Wear recommendations and testing. ENGINE LIQUID FILTRATION - TECHNICAL REFERENCE
or scarring is a sign of inadequate lubricity. Poor
lubricity can result in shorter life of components. What do you need to do during cold weather
Biodiesel can be used as a lubricity improver. months?
Material Compatibility – (Copper Strip Corrosion – When you receive fuel, determine how long it will be in
This test indicates potential compatibility problems storage. Fuel purchased in July does not contain cold flow
with fuel system components made of copper alloys additives. If you will be using this fuel in winter months,
such as brass and bronze.) Biodiesel may not be you may need to add cold flow additives. Like regular diesel
compatible with all materials so it is best to test the fuels, biodiesel blends will gel in very cold temperatures.
entire fuel system to ensure no failures will occur. Typically No.2 diesel fuel has a cloud point in the range of
The material suppliers should be able to assist in the
material testing or may have already completed the -10 to 20°F and No.1 diesel fuel has a cloud point -40°F or
necessary material testing to qualify their materials. less. That means without the use of cold flow improving
additives, No.2 diesel will begin to gel and plug filters at
Water and sediment – This refers to free water their cloud point. Blends of No.1 and No.2 diesel fuel, the
droplets and sediment particles. The allowable use of cold flow additives and/or fuel heating systems are
level for B100 and B6 to B20 blends is set at the frequently used to meet cold flow operability requirements
same level allowed for conventional diesel fuel. for the temperatures expected. The cold flow properties of
Excess water can lead to corrosion and provides an biodiesel blends up to 5% will be virtually the same as those
environment for microorganisms. Fuel oxidation of the diesel fuel used in the blend. Biodiesel blends over
can also raise sediment levels, so this test can be 5% will begin to have higher cloud points and require the
used in conjunction with acid number and viscosity
to determine if fuels have oxidized too much during use of cold flow additives or No.1 diesel in order to operate
storage. It is important to note that biodiesel can in cold winters.
absorb a lot more water than petroleum diesel so
this is a test that should be run frequently to ensure
the fuel is not out of specification.

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