DIESEL FUELS & DIESEL FUEL SYSTEMS

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• What is the maximum particlesize which can pass throughCaterpillar filters?• What is the differencebetween nominal size andabsolute size filters?For example: A nominal 10 micronfilter media (paper) will pass someparticles up to about 50 microns insize. Theoretically, an absoluterating of 10 microns will stop allparticles larger than 10 microns. Infact, filters with absolute micronratings of 10 will pass someparticles larger than 10 microns dueto the irregularity of the paperweave. New filters may pass largerparticles than they will after only afew hours of use.As a rule, Caterpillar fuel filtermedia (paper) is about 3 micronsnominal, 20 microns absolute. Oilfilter media (paper) is about 10microns nominal, 50 micronsabsolute. These are approximatevalues only.Filters are not effectively comparedon the basis of micron rating alone.Evaluate filters on the basis of theirability to collect foreign material as awhole.Primary Fuel Filter ElementSpecificationThe primary fuel filters elementsshould have the following properties:• Mesh Size: 32 x 28 strandsper cm (70 x 80 strands perin.)• Element: Monel wire clothmaterial or equivalent• Element Area: 645 cm2 (100in.2) or greater• Opening Size: 0.1778 mm x0.2235 mm (0.007 in. X0.0088 in.)Duplex Fuel FiltersMany Caterpillar Engines can beequipped with duplex fuel filters asshown in Figure 8.Figure 8These filters may be serviced(change elements), without shuttingoff the engine. There are two types:the symmetrical type, which hastwo identical filter sets and themain-auxiliary type, which has amain filter set and a smaller capacityauxiliary filter set. A special valveconnects the two sets of filters ineach type. The valve routes the fuelto be filtered through either or bothsets of filters.Both filter sets can be usedsimultaneously to extend runningtime in an emergency.Duplex filters for fuel andlubricating oil allow extendedoperation without interruption.©2005 Caterpillar®All rights reserved. Page 25