The gearbox drives the flushing arm with 6 - I O rpm. During prelubrication the filter will keep flushing but with slower rpm. For easy maintenance the complete insert can be removed just by opening the filter cover and pulling out the insert.
To meet the requirement of the classification societies the filter is equipped with overflow valves for 100 '/. flow and a safety filter element with 80 micron. This combination allows the filter to continue flltering the oil even under bad function conditions for a limited time without having the need to shut the engine down. Two alarm contacts indicate increasing differential pressure which may lead to a filter element blocking. The flushing oil can be treated by a centrifugal filter but this is only efficient if it has a separate drive oil connection. Connecting the flushing oil to the centrifugal filter is not efficient because the low pressure downstream of the backflushing outlet results in a low revolution per minutes for the centrifugal filter and therefore to a very low efficiency.
It is recommended and proven by experience that the protection by filtration and the sludge removal can be separated from each other. The best connection for the centrifugal filter is the downstream of the pump but an upstream cooler.
Already a lot of new engine generations have this back-flushing filter directly mounted to the engine.
If products are classified the selfclean type 6.46 belongs to the economic range of products. The upgraded version is the selfclean 6.61 which has a differential triggered backflushing and a multichamber system where most of the filter elements of each chamber are covered with solids. This is acting like a precoat layer and increases the filtration efficiency.
With this type of automatic filter one filter charnber with candles is at stand-by, the rest of it is filtering the oil. As soon as the solids have accumulated on the outer surface of the filter candles the differential pressure for starting the backflushing is reached. One cleaned filter chamber comes into service and one with the solids on the candles will be rotated into backflushing position.
Compressed air will accelerate clean oil in reverse flow through the isolated filter chamber. The air acceleration does cause a pressure peak which makes this unique backflushing system comparable with a high pressure cleaning.
