Offline Filters have been used for decades to effectively control contamination and greatly improve reliability in lubricated machinery. In the world of maintenance and reliability, they are essential. Yet, myths abound about the use of Offline Filters. Some myths arise from general confusion about filtration. Others are simply half-truths or hearsay passed along and accepted as fact. This paper walks through 10 common myths that have been proven wrong – and uncovers a few surprising truths that can help take your reliability program to the next level.
Myth No. 1: I Have an Inline Filter – I Don’t Need an Offline Filter
80% of hydraulic and gear failures can be traced to excessive contamination. This occurs in spite of the fact that these machines come equipped with Inline Filters. Factory supplied filters are often chosen based on the lowest price – not upon their ability to maintain clean oil. An independent study at Tampere University of Technology in Finland showed that 10 leading brands of Inline Filters failed to live up to the filtration ratio printed on the product. Offline Filters make up for this deficit by providing fine filtration in a “kidney loop” process. This involves drawing oil from the bottom of the tank or reservoir and passing it through highly efficient filters to remove contaminants. Once clean, the system will stay clean when using Offiline Filters. Plus, they remove Water, Varnish and Acids that Inline Filters simply can’t.
NOTE: A gearbox came equipped with a highly rated Inline Filter from the factory. In just 3 months after start up and commissioning, the oil was at the condemning level and a complete gearbox replacement was under consideration. Instead, an Offline Filter was retrofitted and in just 10 days the oil was cleaned to better than new levels and the gearbox continues in service to this day (see Figures 1-2).