Therefore, in each fuel system filters are optimally adapted to the requirements of the engine, fuel quality, as well as the foreseen operating conditions. Requirements for fuel filters are very high. In modern engines require capture contaminants as small as 3.5 microns with an efficiency exceeding 90%.
In order to meet these requirements, in many cases installed in the fuel system of multiple fuel filter elements. In this case, unlike the oil filter, for filtering the fuel valves are not by-pass, leaking fuel flow when the filter is clogged, as is the condition necessary to the combustion chamber gets only clean fuel. Thus, it is better if the engine stops due to lack of fuel (clogged filter) than if he would have to work, eating unrefined fuel.