PISTON-CLUTCH 9G0285 - Caterpillar

Industry Standard Filter Ratings
Effective fluid cleanliness management is the single most important factor and the single greatest opportunity in maximizing component life. Managing the fluid increases reliability and durability, and lowers component life cycle costs. Caterpillar is committed to providing customers with high quality, cost-effective filtration products designed to meet specific performance requirements. Caterpillar has never published micron ratings because the numbers can be misleading or easily manipulated. Many medium and low quality filters are marketed by using a micron rating only. Stating a micron filter rating without stating the filter efficiency rating is useless, and has no official standing within filter industry technical groups such as the Society of Automotive Engineers (SAE) or the National Fluid Power Association (NFPA).While the micron rating of different filters may be the same, the ability to trap particles of that size and larger varies dramatically. The primary method to rate a filter is to state the efficiency of removing and retaining particles of a certain size, measured in microns.Competitive marketing efforts are based solely upon the multipass test. This test is a standard industry test with procedure published by the International Standards Institute (ISO), the American National Standards Institute (ANSI), the National Fluid Power Association (NFPA), and the National Institute of Standards & Technology (NIST). The ISO 16889 laboratory test inserts a concentrated stream of artificial contaminants. The test is under a predetermined constant flow and other steady state conditions. The conditions are to load the filter until a specified pressure drop is reached. During the test, particles entering and exiting the filter are electronically counted. A ratio of the particle concentration upstream to the concentration downstream is called the filtration ratio or beta ratio. The filtration ratio, or beta ratio, is a measure of the efficiency of the filter at capturing particles of a certain size. Standards related to the multipass test are listed in Table 1.
Table 1
Changes in Industry Standards    
Previous     Current 1999     Description    
ISO 4406     ISO 4406:1999     ISO Range Code    
ISO 4402     ISO 11171     Automatic Particle Counter (APC) calibration procedures (ACFTD to ISO MTD)    
ISO 4572     ISO 16889     multipass test reports    Illustration 1 shows typical particle count data for a single filter at two different particle sizes and the resulting beta ratios. The data on the left (for particles 6 microns and larger) is said to indicate a beta ratio of 2. The data on the right (for particles 14 microns and larger) indicates a beta ratio of 75. The particle size (or microns at which the beta ratio is calculated) is shown as a subscript to the beta symbol. Standard industry practice when reporting test results obtained using the ISO 16889 test method is to follow the micron rating with a small letter "(c)" inside brackets. This notation distinguishes between test results obtained using the old versus the new test methods and test dusts.If 2,000 particles 6 microns or greater are counted upstream and