PART A- CONTAMINATION
Types of Contamination.
A contaminated product is one that contains some material not normally
present, such as water, solids, or other grades of petroleum products. Such a mixture may modify the quality of
the product permanently or add undesirable characteristics. Contamination usually results through carelessness,
accident, inability or neglect to follow procedures or through sabotage.
Water Water may be fresh or salt. Saltwater will be present as free water, where freshwater can be present as
either free or dissolved water.
Examples of water contamination in bulk storage tanks. Conical, flat, and dome roof tanks can become
contaminated by rain, snow, moisture in the atmosphere, water bottoms present in the tanks, or line flush.
Floating roof tanks are usually contaminated when the roof seal becomes unserviceable and leaks or if
the roof drain lines that allow collected water on the roof of the tank to drain off become clogged. Water
contamination of pipeline can occur when the line flush is pumped into the line or if water collects in low
spots along the line. Tankers can become contaminated if the hatches are left open and rain or waves
get into the tank.
Effects of water contamination. If a product is contaminated with water, sludge will form, the fuel will not
burn efficiently, the water in the fuel can freeze or cause rusting in the storage container, and it will
support microbiological growth.
Indications of water contamination. The appearance of lube oils will be milky, and light distillates will
appear hazy or cloudy. The water by distillation and the bottom sediment and water tests will show the
presence of water, and a product will start foaming at approximately 200 degrees Fahrenheit when being
tested for flash or fire points.
Recommendations for use. The product should be passed through a filter/separator to remove water. It
can be dehydrated by heating. In the case of lube oil it is usually sent to the Defense Reutilization and
Marketing Office (DRMO).
Solid Contamination. Course sediment is sediment which is larger than 10 microns in size. Fine sediment
is sediment which is smaller than 10 microns in size.
Definition: Any form of sediment may clog filters or injector nozzles of aircraft fuel systems. The abrasive
action of this sediment may cause damage to finely tooled fuel system components. Large particles
usually indicate a failure somewhere in the fuel system.
Examples:
Rust: A product of corrosion. It is brittle and powders readily. It is insoluble in water. It is usually
caused by water present in the system or from empty containers once they are put into service. Rust
can usually be removed by passing the fuel through a filter separator.
Millscale: Is a magnetic product formed on iron and steel during the manufacturing process. It is blue
black in color and is brittle. It is usually found when new tanks or pipes are first placed into service,
can be removed by filtering and usually will not settle out of fuel.
Bronze: If present in fuel it is usually caused by worn impellers in the fuel pumps.
Lint-fibers: Caused by paper type filter cartridges, cloth, and cotton waste. Some fibers cannot be
detected without microscopic examination. Can usually be corrected by changing the filter elements.
However it is sometimes caused when new filters are placed in service.
Effects of solids contamination include clogged fuel filters and lines, increased wear of parts caused by
abrasion, and increased maintenance. Recommendations for use: Allow fuel to settle, pass product
through a filter/separator, and, if solids are removed, use for intended purpose.
Commingling. Commingling is the accidental mixing of two or more products and can be a serious or minor
problem depending on the product that was contaminated, type of contaminating product, or degree of
contamination.
The effects of commingling varies with each product; however, usually there is a change in product color
and specification. Critical tests that are normally affected include Reid vapor pressure, flash point, and
distillation.
Indication of commingling can be detected by a color change in the product and the API gravity. Both the
visual color and the gravity of the fuel should be checked on a regular basis at the storage location.
QM 5184
4-2
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