As a petroleum laboratory supervisor, you must utilize laboratory test results to identify petroleum
contaminants, determine the cause of the contamination, and interpret test results to follow-up and correct
PART A - IDENTIFY PRODUCT PROPERTIES THAT COULD INDICATE
Fibrous material. When looking at a clear quart glass container, fibrous material will appear as pieces
of thread-like material, similar to fiberglass threads, suspended in the product or lying at the bottom of the
Sediment. This will appear as dust, powder, flakes, and/or granular material. Total sediment includes
both organic and inorganic material. You may categorize sediment either as coarse or fine.
Coarse sediment. Sediment which easily settles out of the product or can be removed by filtration.
Ordinarily, "coarse sediment" refers to particles of 10 mn (micron) size or larger. This type of sediment
is quite visible in a clear glass container.
Fine sediment. Sediment that is smaller than 10 microns. To a limited degree, this type of sediment can
be removed by settling or filtration. Fine particles are not visible to the naked eye as separate or distinct
particles. However, the particles will scatter light and may appear as pinpoint flashes of light (like the
shimmer of a diamond) or as a slight haze in a sample.
Microbiological growth. This growth consists of living organisms that grow at the fuel-water interface.
These organisms include protozoa, fungus, and bacteria, and they normally have a brown, black, or gray
color in addition to a stringy, fibrous-like appearance when observed in a clear glass container. Removal of
water bottoms will prevent this problem.
Water. Water in fuels may be either fresh or salty and may be present as either dissolved, entrained, or
Dissolved water. This is water that has been absorbed by the fuel and is not visible during sample
inspections at ambient temperature. Dissolved water is not a problem as long as it remains in solution.
When the fuel is cooled, dissolved water can fall from a solution. Fuel System Icing Inhibitor (FSII) is
added to jet fuels to prevent dissolved water from freezing. FSII is also used in diesel fuels and can be
used in GT.
Entrained water. This is an emulsion of water in fuel and is visible as a cloud. Entrained water can be
removed by filtration.
Free water. This is water that may appear in the form of a cloud, emulsion, emulsion droplets, or in
larger amounts in the bottom of a tank or other container. Free water is normally readily detectable
during visual sample inspections and settles out in storage within 24 hours.
Commingling. Commingling is the accidental mixing of products that usually occurs when too much
interface mixture is pumped into the storage tanks. Upon settling, the contaminants will not normally stratify
into layers in the tank. For example, DL-2 blends very well with JP-8. However, it renders both the JP-8 and
DL-2 as NSFU.
PART B - EXAMINE THE HANDLING HISTORY OF THE PRODUCT TO
PINPOINT THE SOURCE CONTAMINATION
Although you can visually detect some contaminants, you will frequently have to detect others through
laboratory analysis. Normally, for visual observations, you will check the product for color and appearance.
Checking for color and appearance are part of a routine laboratory analysis and are also helpful in detecting
products containing coarse or fine sediment and water. The visual test will draw one's attention to possible
sediment contamination or to a commingled product. For example, a cloudy sample of JP-4 from a fuel