How ´fine´ should the filtration process be?
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The most common cause of failure in hydraulic components is the presence of solid impurities. This problem is primarily due to the penetration of particles from outside and, to a lesser extent, the generation of abraded matter within the system. So far, relatively little is known about the wearing processes within hydraulic systems and, for this reason, users rightly expect the filter manufacturer to guarantee the right ´economic´ oil purity class for the system in question. Since it is neither technically nor economically feasible to remove ´all´ solid particles from the circuit with micro-filters, the practice nowadays is to define reliable contamination categories. In other words, it is up to the plant engineer in collaboration with the filter manufacturer to determine the reasonably permissible degree of contamination, the condition prior to start-up and the operating conditions of the plant. The user should also find out the permissible oil purity classes from the component supplier, so that the filter manufacturer can create the necessary preconditions based on the most sensitive component in the system (e.g. servo-control, etc.). At the same time, however, the truth of the principle ´Not as fine as possible, but as fine as necessary´ is borne out by scientific research according to which it may also be possible to filter out additives in the oil containing dirt particles partly in suspension. This level of precision is where magnetic filtration comes in, as it cannot damage the structure of the pressure fluid. |
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