# Filter micron rating

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#### 98Auburn

I'm sure this has been addressed already. I have a question on how NAPA and WIX show there bata rating. Lets say for a 1607 NAPA gold filter spec says bata 2/20=17/27. Does this mean at 2 microns a beta rating of 17 or 17 micron at a beta rating of 2?

This means at 2 microns the filter is (17-1)/17 or 0.941 or 94.1% efficient and at 20 microns the filter is (27-1)/27 or 0.963 or 96.3% efficient.

Make note of the colors of the numbers in "Beta 2/20=17/27". What this means is the filter is: 50% efficient (beta 2) at 17 microns and 95% efficient (beta 20) at 27 microns The KEY here is to know that red goes with red ... blue goes with blue. First set of numbers (2/20) are the beta numbers. Second set of numbers are the particle micron sizes. WIX and NAPA always use the 2/20 beta numbers (50% and 95% efficiency) in their beta specs.

Zee, I understand what you mean. I was hoping for the sake of filter efficiency the ratings would be the way Cowboy posted. Can anyone else confirm what Zee is saying?

Originally Posted By: 98Auburn
Zee, I understand what you mean. I was hoping for the sake of filter efficiency the ratings would be the way Cowboy posted. Can anyone else confirm what Zee is saying?
ZO6 is the beta man, I learned it from him and it's exactly the way he has it written. Just to add to it, if the first number is 2, think 1 over 2 or 1/2 = 50%, then subtract that from 100%, =50% efficient at the corresponding micron level. In the example above @ 17um. The 20 would be 1/20 or 5%, subtract from 100% = 95% @ 27um(ex. above). Another way to think of it is, the example media allows 5% of 27um particle size through. Imo, ZO's explantion using color seems an easy way to understand the beta #'s and how to decipher them.

ZO6 is correct. I had it wrong.

Here's some more info on Beta Ratio and how efficiency is calculated from the Beta Ratio. Beta Ratio = B Efficiency % = (B-1)/B x 100 Here are some Beta Ratio vs. Efficiencies. Beta Ratio -- Efficiency 2 -- 50.0 5 -- 80.0 10 -- 90.0 20 -- 95.0 30 -- 96.7 40 -- 97.5 50 -- 98.0 60 -- 98.3 70 -- 98.6 80 -- 98.8 90 -- 98.9 100 -- 99.0 200 -- 99.5 300 -- 99.7 500 -- 99.8 1000 -- 99.9 sayjac make some good points. Also, if you want to read up more about Beta Ratio, just Google it and you'll find lots of good info.

Plus, you need to know if the ratings are single pass or multi pass. If the filter removes 50% of the 17µ particles every pass, it would remove a much higher percentage with multiple passes of the fluid.

Originally Posted By: Ken2
Plus, you need to know if the ratings are single pass or multi pass. If the filter removes 50% of the 17µ particles every pass, it would remove a much higher percentage with multiple passes of the fluid.
True ... and to add, most filter makers these days test to ISO 4548-12 (I know Purolator does per their website info), which is a multi-pass test. Details below. The ":2000" means this test was established in year 2000. ISO 4548-12:2000 ---------------- Methods of test for full-flow lubricating oil filters for internal combustion engines -- Part 12: Filtration efficiency using particle counting, and contaminant retention capacity. This part of ISO 4548 specifies a multi-pass filtration test with continuous contaminant injection and using the online particle counting method for evaluating the performance of full-flow lubricating oil filters for internal combustion engines. The test procedure determines the contaminant capacity of a filter, its particulate removal characteristics and differential pressure. This test is intended for application to filter elements having a rated flow between 4 l/min and 600 l/min and with an efficiency of less than 99 % at a particle size greater than 10 microns.

Gentleman, thank you for the info. Another question for the pros. Caterpillar has a line of Ultra High Efficiency engine oil filters that claim to have an absolute rating of 10 micron. In my mind that would be a high quality full flow filter. part #244-4484 What do you think?

Originally Posted By: 98Auburn
Gentleman, thank you for the info. Another question for the pros. Caterpillar has a line of Ultra High Efficiency engine oil filters that claim to have an absolute rating of 10 micron. In my mind that would be a high quality full flow filter. part #244-4484 What do you think?
98.7% efficient at 10 microns is pretty good IMO. Read below. From Technical Service Bulletin 89-5R3a from the Filter Manufacturers Council. "The two most popular reported media ratings are a nominal micron rating (50%) and an absolute micron rating (98.7%). A nominal rating usually means the filter's media can capture a given percentage of particles of a stated size. For example, a filter might be said to have a nominal rating of 50% for particles 10 micrometers in size or larger. An absolute micron rating can be determined by single-pass or multi-pass testing and is usually obtained by passing a test fluid containing particles of a known size through a small, flat sheet of filter media. Any particles that pass through the media are captured and measured. An absolute rating is also expressed in the form of a percentage of the size of particles captured."

My information was wrong. Less than 15 micron absolute on the engine oil and less than 10 micron on hydrolic and transmission filters. Thats not a bad full flow filter with a bata rating of 75.

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