Importance of Engine Lubricity ...
What is lubricity in fuel and why is it important?
Lubricity is best described as the ability of a fluid or lubricant to minimize
the friction and damage between surfaces in relative motion under load. In
a diesel engine the fuel is part of the lubrication process but with current
regulations continuously enforcing stricter emission standards on diesel
fuels, the importance of fuel lubricity has become a major concern to both
engine manufacturers and users. We know that without lube oil in an engine
all of the metal parts in the engine will rub against each other causing
catastrophic wear and damage, we can safely say the same about the fuel
components thus making fuel testing a critical element to determine or
measure the lubricity. Due to the fine tolerances of the components within
the fuel-injection system, some of which are measured in ten-thousandths
of an inch. If the fuel’s lubricity is too low, improper lubrication will shorten
the service life of fuel injectors and high-pressure pumps. They will
essentially grind themselves to death. Insidiously, this failure typically
doesn’t display any outward symptoms; the engine runs just fine, there’s no
smoke or knocking, and fuel economy remains normal until the engine
becomes difficult to start or the injection pump fails, by which time the
damage is done.
As diesel fuel is further refined to remove the polluting sulfur, it is
inadvertently stripped of its lubricating properties. This vital lubrication is a
necessary component of diesel fuel as it prevents wear in the fuel delivery
system. Specifically, it lubricates pumps, high pressure pumps and injectors.
Traditional Low sulfur diesel fuel typically contained enough lubricating
ability to suffice the needs of these vital components. ULSD fuel, on the
other hand, is considered to be very “dry” and incapable of lubricating vital
fuel delivery components. As a result, these components are at risk of
premature and even catastrophic failure when ULSD fuel is introduced to the
system. According to multiple diesel studies and engineers there is a
common belief that All ULSD fuel purchased at retail fuel stations
SHOULD be adequately treated with additives to replace this lost
lubricity. The potential result of using inadequately treated fuel, as
indicated above, can be catastrophic.
There have been many documented cases of randomly tested samples of
diesel fuel. These tests prove that often the fuel we purchase is not
adequately treated and may therefore contribute to accelerated wear of our
fuel delivery systems. For this reason, it’s important to use DF5 to ENSURE
adequate lubrication of the fuel delivery system. Additionally, DF5 offers the
added benefits of a Cetane improver, that eliminates the need for a separate
anti-gel in the winter.
In today’s advanced, high-pressure diesel systems, both the pump and
injector rely solely on fuel for their lubrication. This sets the stage for
prevention of diesel lubricity problems.
Since the switch to ULSD (Ultra Low Sulfur Diesel), fleet owners and regular
diesel users alike have complained about the following:
• Lower energy content (BTUs) compared to low sulfur diesel (LSD),
resulting in lower fuel economy.
BTU is the unit used to measure heat energy and is also known as
British Thermal Units. Larger BTU readings and output mean that
your fuel is stronger and produces more power per stroke. Pretty
similar to the logic behind the octane levels for gasoline. Prior to
2006, LSD fuels ruled the day. Now ULSD fuels are the standard and
requirement since changes were made by the EPA to reduce
emissions. Sulfur is the keyword here, as it’s the lubricant for the
fuel and affects all system components related to combustion.
Lower energy content means the engine needs to burn more fuel to
create the same output of power as a fuel with higher energy
content, resulting in less fuel economy.
• ULSD is a hygroscopic fuel, meaning that it absorbs moisture from
the air or atmosphere.
This is an important point. Water wreaks havoc in diesel fuel
systems causing corrosion and failure of metal components, such as
fuel tanks, pumps and injectors. Absorbing moisture from the air
can also make your fuel go bad much faster. Fuel going bad will
result in lower energy content (BTUs) and overall lower
performance. The moisture absorbed from the air can also lead to
formation of rust inside the fuel tank. The presence of rust not only
affects the fuel but can also clog up filters or worse, injectors and
pumps. In the wintertime, the presence of moisture leads to “diesel
gelling”. Diesel fuel changes it’s liquid state into solid, clogging
everything and making your truck or other diesel burning vehicle
unusable.
• Reduced levels of lubricity
Since diesel systems rely on the lubricity of the fuel to function
correctly, a reduced level of sulfur will increase wear and the
possibility of other complications appearing throughout.
Above mentioned are the elements discovered by users at first glance.
However, fuel systems can develop ULSD related problems in the long run.
Most commonly, these issues are:
• Rust and corrosion form in lines as well as fuel tanks. This happens
due to the aggressive chemicals within the fuel and because of its
hygroscopic nature.
• Low fuel lubricity causes wear or scarring in pumps and injectors.
Lack of lubrication affects especially expensive and accurate
components that work with very small tolerances.
• Sludge can build up inside tanks and result in plugged filters. Sludge
or diesel fuel algae is a microbial biomass formation that appears due
to the ULSD’s moisture attracting nature. It forms a jelly, slimy
contaminant that will work to clog up filters or injectors and pumps as
previously mentioned.
Independent Laboratory Testing...
DF5 was tested using two different third-party independent laboratories,
which is preferred by manufacturers and is industry standard. Quality of
diesel related to its lubricity is determined using the high frequency
reciprocating rig (HFRR), it is a wear test method that was developed by
Infineum and Imperial College in London. The design, test method and
results from HFRR are well described in standards like ASTM D6079 and ISO
12156. HFRR is a powerful tool in lubrication, as it is become a key enabler of
pollution control. HFRR test method is recognized by several regulatory
bodies that control the quality of diesel and its emission of pollutants ( see
attached SWRI Lab Test).The results of the independent testing showed a
16% increase in lubricity after adding DF5 to the fuel (see attached SPL
Laboratory Test).
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