We are seeing a significant number of customers
that are having problems with the filters on their diesel fuel dispensers.
In nearly every case the customers are receiving a B2 to B5 blend.
In most of these cases they are not having
vehicle or equipment problems, but rather problems getting the fuel from the
storage tank to the vehicle tank. The dispenser filters seem to plug anywhere
from a few hours to a few days of operation.
These filters when opened contain what at first
appears to be wax. However when analyzed this material appears to be a
glycerin type material. If you then bottom sample the storage tank, you
generally find a material that resembles cottage cheese. There is often a
layer that starts at the tank bottom and can be several inches thick of this
When this layer reaches the level of the pickup
tube it can very quickly plug the dispenser filter.
This issue has several variations and we have
identified several potential causal factors.
Fuel that has a high level of dissolved water.
This high water content seems to be a significant factor in all of these
Fuel derived from animal fats (including plant / animal blends of biodiesel)
seems to be a factor in these problems.
Long periods (more than 72 hours) of temperatures below 32 °F (the longer it
is cold and the colder the average temperature the greater the problem).
Above ground versus in-ground fuel storage.
Use of additives – Some help, some make things
CP, CFPP, PP of the diesel portion of the blended fuel.
Quality of the blend procedure and temperature
at which the fuel and biodiesel are blended.
Another factor in the rapid plugging of these
dispenser filters is that as filter media starts to plug the filter actually
begins to reduce the micron size of the media so that the filter picks more and
more material that is smaller and smaller.
Also consider that a diesel engine tends to heat
the fuel during the recirculation process whereas a dispenser provides no heat.
We offer some suggestions for users experiencing
If you have this problem today you can go to a
dispenser filter with a large micron size. There are winter filters
available from Cim-Tek with a cleanable 144 micron stainless steel mesh.
You can have the tank pumped from the bottom to
remove this material. Depending upon your tank size, you may need to remove
50 to as much as 300 gallons to eliminate this problem.
You can add certain types of additives that
will break this material down and return it to solution.
You can add kerosene (Note: if you have
Ultra-Low Sulfur Diesel, you MUST use Ultra-Low Sulfur Kerosene). ULSD
Kerosene is very expensive and it can take a lot of it to resolve this
Ask for your next two or three loads of diesel to be delivered with no
Ask for biodiesel blends derived only from
plant base oils during the fall and winter months.
Additization with the correct products can help
to prevent these problems.
If you have access to biodiesel that has been through a distillation
process, you will have far less problems.