Technical Reference
Combining the ISO Rating and Filter Performance Ratings Many of the components with filters have recommended or specified fluid cleanliness levels to ensure their performance and longevity.This is usually specified per ISO 4406 and with a three number rating expressed in x/y/z format. In this rating each number is a code representing the number of particles greater than a certain size. While filters, on the other hand, have a given efficiency performance based on the media used which is usually expressed in a beta rating or efficiency percentage. A direct connection between the beta rating scale and the ISO rating scale cannot be made. Many application differences exist in engine liquid filters that need to be understood to begin to correctly apply a filtration media to obtain a desired fluid cleanliness. For example, is it a contained system like the lube oil system where the same fluid is re-circulated and the fluid will be put through the filter multiple times (multi-pass) or is it a fuel system where the fluid is consumed and needs to be cleaned in one time through the filter (single pass). What is the fluid cleanliness that is being started with and what are the application environmental conditions.These are just of few of the things to consider when choosing the correct media to apply. The ultimate solution is monitoring filter media performance at removing particles in the 4 μm, 6 μm, and 14 μm ranges.
Fluid analysis and field monitoring are the only ways to get these measurements. Combine data from several tests to form a range of performance. Remember, actual filter performance will vary
between applications. ISO Rating System The international rating system for fluid
contamination levels is called the ISO contamination code and it is detailed in the ISO 4406 document. Many component manufacturers publish filtration level recommendations using the ISO code. Manufacturer’s ISO contamination levels are based on controlling the particle counts of 4 μm, 6 μm and 14 μm particles in the system fluid.This level is identified by measuring the number of particles 4μm and greater, 6 μm and greater, and 14 μm and greater in one milliliter of the system fluid sample.
Range of number of particles per milliliter Code More Than Up to & Including 24 80,000 160,000 23 40,000 80,000 22 20,000 40,000 21 10,000 20,000 20 5,000 10,000 19 2,500 5,000 18 1,300 2,500 17 640 1,300 16 320 640 15 160 320 14 80 160 13 40 80 12 20 40 11 10 20 10 5 10 9 2.5 5 8 1.3 2.5 7 .64 1.3 6 .32 .64 5 .16 .32 4 .08 .16 3 .04 .08 2 .02 .04 1 .01 .02 ISO 4406 Contamination Codes
ISO 18/16/13
µm
4 6
14
à
Engine Liquid Filtration • 55
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