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The physical effects of microbiological
contamination are the formation of biological sludges, biofilms (slimes) and
surface or interfacial scums. These mainly occur in the fuel tank and also
manifest themselves as material which block filters.
A number of microbial and chemical
processes produce corrosive by-products including strong organic acids and
sulphides. These can degrade protective coatings such as paints, rubber,
some plastics and metal oxide films as well as destroy or inactivate
chemical corrosion inhibitors and cause hydrogen embrittlement of metals.
Black deposits on copper or copper containing alloys in pipe work and
bearings as well as pitting are evidence of microbial induced corrosion.
Engines rely on high quality fuel that has
been properly filtered and separated (from water), with no flow
restrictions, to achieve proper atomisation, combustion, engine performance
and fuel efficiency. Fuel that is infected with bacteria is not reliable and
there are many and varied consequences of using contaminated fuel.
These include:
1. encouraging growth of further
contamination
2. fuel filter clogging and blockage
3. coalescer malfunctions
4. engine wear due to variations in fuel flow
5. corrosion of the fuel system
6. corrosion of engine fuel injectors
7. damage to in-line instruments
Engine fuel injection equipment and fuel
pumps are most susceptible to the effects of microbial contamination
resulting in corrosive damage.
Ultimately, performance suffers and fuel consumption and maintenance costs
increase, but perhaps the most critical concern is the real potential for
blockages in the fuel system which cause engine failure while underway -
with potentially devastating consequences.
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