Diesel Fuel Contamination
Generator Engines may be exercised regularly and operate properly and to specification. However inside the fuel tank, out of sight, free and emulsified water is slowly accumulating from condensation and even fuel deliveries with high water absorption. As the evening temperature falls the water begins to condense out of the fuel and build inside of the tank.
If any water is on the storage tank bottom colonies of filter clogging bacteria and fungus will grow at the fuel/water interface. The by product of these colonies is acidic sludge.
When the fuel/water interface grows high enough to reach the engines fuel supply tube which may be inches above the tank bottom; the filter clogging microbes will be drawn into the fuel system and stop the engine.
99% of all fuel contaminates; including water, are heavier than fuels and will be found on the storage tank bottom.Remove the tank bottom water and the micro-organisms will die.
Therefore it is imperative that the fuel polishing systems intake supply tubes be located on the lowest portion of the storage tank bottom. Failure to do so may result in unexpected engine shutdown.
The fuel polishing system must be independent of the engines fuel supply.
A properly installed Fuel Polishing System will prevent
the emergency generators from becoming the Emergency.
Microbes found in diesel fuel
Virtually all diesel fuel contains some moisture. Additional water accumulates in tanks asatmospheric moisture condenses. Moisture accumulates in diesel tanks as condensatedroplets on exposed tank surfaces, as dissolved water in the fuel and as water bottoms beneath the fuel microbes depend on this water for growth. Additionally, microbes depend on the organic and inorganic molecules indiesel fuel for nutrition. Consequently, some species attack the fuel directly, growing at theexpense of hydrocarbons and non-hydrocarbon fuel components. The biodegradation offuel, in support of microbial growth, is a direct impact of contamination. Color, heat ofcombustion, pour point, cloud point, detergent and anti-corrosive properties change asmicrobes selectively attack fuel components. Sulfur-containing molecules are metabolizedby a series of species, leading ultimately to the production of high concentrations ofhydrogen sulfide. In addition to creating new cells, many microbes produce metaboliteswhich promote further attack. Surfactants facilitate the emulsification of fuel, leading to theformation of a cloudy, invert-emulsion layer above the fuel/water interface.Polysaccharide slimes create microenvironments wherein mixed populations (consortia)of bacteria and fungi carry out biodegradation reactions that would be impossible for a singlespecies outside the microenvironment. The slime also serves as a barrier, protecting themicrobes from preservatives. A variety of organic acids (primarily 2 -4 carbon atoms) are also produced as by-products of bacterial and fungal growth.
