Biodiesel and Cold Weather
Issues
We have recently seen a new cold weather problem related blended
biodiesel fuels.
The problem has been seen with B5 and greater blends where the diesel portion
has been treated with certain lubricity agents.
What is being seen is that when the stored fuel is cold (below 15F) for extended
periods of time (generally 48 hours or more) the dispenser filters will plug
with an orange colored material. When this fuel filter is removed and the fuel
poured out into a container that will allow it to be viewed you see an orange
cloud floating in the fuel. The colder it gets the more of this material is
found in the filter.
This appears to be the result of the fuel becoming more viscous as it gets
colder. As the fuel becomes thicker it will begin to reduce the pore size of the
filter media. As the pore size gets smaller, the filter begins to filter out the
lubricity additive and the filter will concentrate it until the restriction is
such that little or no fuel will pass through the filter.
This is a separate issue from gelling. The fuel when tested can have a very good
Cold Filter Plug Point
(CFPP) or Low
Temperature Flow Test (LTFT) number and still see this problem.
Diesel Doctor
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