personnel handling the product. Therefore, the quality at issue depends on laboratory control programs. The
most common forms of deterioration are weathering, gum formation, and loss of additives such as FSII and color.
(1) Weathering. Weathering is the loss of the more volatile components of some products. Its effects
are most noticeable in aviation and motor gasolines. Because these products produce enough vapor pressure to
rupture a sealed storage tank, the storage tanks are vented to the air. As the temperature rises, vapor is pushed out
the vents. As the temperature falls, air is sucked in the vents. Through this cycle, the products lose their more
volatile components. The more volatile components are needed for easy and cold weather engine startup and
engine warm up. The less volatile fuel may cause trouble in engine performance.
(2) Gum formation. Gum formation is the most common and troublesome form of deterioration. It is
caused by the presence of unsaturated hydrocarbons in the fuel. In the presence of oxygen, these unsaturated
hydrocarbons change into gummy, and eventually resinous, materials The gummy substances remain in solution
but are difficult for the engine to vaporize and can form deposits on the cylinder walls of engines and carburetors,
eventually clogging them. The gum deposits also increase the carbon build up in engines, resulting in higher
costs of engine maintenance. The resinous materials settle to the bottom of the product as they are formed but are
very difficult to clean out of the bottom of the container. Gum and resin inhibitors are added to products but are
effective for a limited time only.
(3) Loss of additives. The causes of the loss of additives, such as FSII, and color, have not been
established with certainty. These forms of deterioration are considered together because they are all known to
occur during storage. The loss of additives may be a postponed result of manufacturing mistakes, poor product
handling, or contamination. The effect on the product is determined by what type of additive was lost. For
example: Losing oxidation inhibitors decreases the length of time a product can be stored; loss of color by itself is
unimportant but indicates that the product has been oxidized and further evaluation may be necessary; loss of FSII
could allow fuel lines to freeze at higher altitudes. Good petroleum handling and quality surveillance measures
are the best way to prevent loss of additives.
c. Reclamation and Disposition.
(1) Generally, suspected deterioration or contamination must be confirmed by laboratory test.
Reclamation refers to the procedures required to restore or change the quality of the product to make it usable.
The laboratory should be consulted before any procedures to reclaim products are initiated. The methods of
reclamation include downgrading, blending, filtering, dehydrating, and inhibiting. It is preferred to restore the
product to its original intended use by the most cost effective method; if this is impractical or impossible, then the
next priority is to make the product usable at some level. In deciding which reclamation method to use, consider
the following factors:
10-13
QM5200
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