Unfortunately out of spec fuel is not uncommon. The most
common cause is water contamination. Other causes include cross contamination,
aging and sediment. Sometimes fuel
arrives to the end user out of spec due to a refining, storage or
transportation problems. There can be many variables contributing to bad fuel.
Therefore it is important to identify when it is out of spec. With fuel markets
in over 150 countries and numerous fuel grades and specifications, it would be
a voluminous task to repeat them here. However, knowing your specific market
and the requirements set for each fuel grade is very important.
There are some measurable factors that help narrow down fuel
quality standards regardless of where you might live.
in gasoline, while not the most important factor to fuel quality, it does have
a lot to do with how an engine runs. The octane number of gasoline determines
how capable a gasoline engine is able to resist knocking during combustion. If
the octane is too low, an engine will knock or ping and if frequent enough,
damage can happen over time. Generally, retail gasoline octane ranges from 87
to 94. Octane effects the performance of an engine. Using the engine
manufacturers specified octane fuel is advisable.
in diesel fuel is akin to octane in gasoline.
It is an indicator of combustion.
If the cetane is too low then ignition may be impaired. Typically cetane ranges between 40 and 60.
Over 110 countries specify a cetane of 48 or greater. Low cetane can result in poor engine power
and performance. Continued use can
result in engine damage.
is possibly the most damaging contaminant in fuel. Measuring fuel quality includes
identifying contaminants and adulterations. While it is impossible to be 100% perfect,
free water should always be removed. When water reaches its saturation point in
fuel, it becomes free water. If the fuel is ethanol free or ULSD then the water
drops out of the fuel and settles to the bottom where is can be removed. If the
biofuel is present, a considerable amount of water could remain in suspension
and damage the engine or keep it from running.
Number of fuel is significant. Acidity in petroleum can come from organic
sulfur and naphthenic acids. Acids are also a byproduct of microbial infection.
A high acid level will always indicate a problem warranting further
Stability concerns the stability of the fuel composition. All fuel degrade
over time, however FAME degrades faster due to its lower oxidation stability.
Heat, water and contaminants accelerate degradation and reduce the oxidation
stability of fuel. As gasoline degrades, gums form that leave a residue fouling
filters and damaging engine components.
As diesel fuel breaks down it leaves solid deposits and Asphaltenes to
coat and damage systems.
Contamination in fuel is not always evident. Once it is visibly identifiable
in fuel immediate action should be taken. System and engine corrosion is a
primary result of microbial contamination. Because most fuel eating microbes
create acidic byproducts, acids that accelerate corrosion, microbial influenced
corrosion (MIC) is an industry wide problem.