See All 14 Photos Bypass Filtration 101:Things You Need To Know Absolute Micron Rating:The smallest particle of which a filter can catch nearly 100 percent of (typically above about 98.5 percent ...

Instead, the marketing departments tend toward vague terms, typically claiming a "micron rating" that ... is 15 grams at 8 psi for a filter with a built-in bypass valve, typically identified ...

The second interesting valve is the bypass valve ... rating is simply a measure of the percentage of ~20-micron dirt particles that the filter can capture over a certain duration.