Standardized Efficiency Testing for Air Filters

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I've not been able to find an answer to this, so if anyone has a source, please direct me there and we can just shut this thread down.

Finding an oil filters efficiency rating is rather easy as MOST manufacturers will post the ISO 4548-12 results. However, air filters don't seem to get the same treatment. I know that ISO 5011 exists, but I've not seen that actually cited on MANY air filters. A few examples of language can be found below. Does anyone have an answer as to why this hasn't been standardized like it has with oil filtration? Considering as how air filtration is far more important, it would seem like those numbers being readily available would be most beneficial to the consumer.

Fram EG - "2x engine protection"
Fram TG - "Traps double the dirt"
PureOne - "Traps upto 99% of damaging debris" (Based on ISO 5011 for A24278, no micron rating given)
STP - "Air filters are ISO 5011 tested to meet or exceed OEM fit and quality requirements"
 
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Originally Posted By: RamFan
... Finding an oil filters efficiency rating is rather easy as MOST manufacturers will post the ISO 4548-12 results. However, air filters don't seem to get the same treatment. ... Does anyone have an answer as to why this hasn't been standardized like it has with oil filtration? Considering as how air filtration is far more important, it would seem like those numbers being readily available would be most beneficial ...
Good question! I think they don't won't us to know. None of the vague advertising claims you quoted make a lick of sense, except possibly STP's.
 
Originally Posted By: CR94
Originally Posted By: RamFan
... Finding an oil filters efficiency rating is rather easy as MOST manufacturers will post the ISO 4548-12 results. However, air filters don't seem to get the same treatment. ... Does anyone have an answer as to why this hasn't been standardized like it has with oil filtration? Considering as how air filtration is far more important, it would seem like those numbers being readily available would be most beneficial ...
Good question! I think they don't won't us to know. None of the vague advertising claims you quoted make a lick of sense, except possibly STP's.


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That correct they don't like posting the truth about their products. They need a little help it needs to be standardized and require the results printed on the products box.
 
"Considering as how air filtration is far more important, it would seem like those numbers being readily available would be most beneficial to the consumer."

I think that might be a clue as to why they aren't.

Plus there's the cost of testing. Its conceivable that some manufacturers who aren't OEM suppliers don't actually know (or particularly care) how well the product works, since they get little back pressure from the consumer.
 
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From K&N...

https://www.knfilters.com/faq.htm#5

5. What is the micron rating and efficiency of a K&N air filter?
Automotive air filters are not rated by micron size, they are rated by efficiency. K&N tests the filtering ability of our air filters using the ISO 5011 test procedure. In general, most K&N air filters will test between 97%-99% efficiency. Some air filters have their air filter test data published in the Available Information section of the product details page for that part number.

6. What are the air filtration requirements for my vehicle?
We are unaware of any vehicle manufacturer having published specific filtration requirements for any of their vehicles. As per the rights guaranteed under the Magnuson-Moss Warranty Act, consumers are free to use any brand of replacement part in their vehicle, without affecting the vehicle's warranty. Having specific filtration requirements would limit consumers' choices, and would not be viewed favorably by the Federal Trade Commission.

7. Some air filter companies tout their high filtration levels in the 99th percentile. Doesn't higher filtration mean a better air filter?
Not necessarily. 99% filtration efficiency is certainly a very good achievement. However, filter efficiency is just one statistic of filter performance which is measured (but is also the statistic most commonly published). The other air filter performance statistics measured are: capacity, restriction, and service life. These other factors reflect the amount of dirt the filter can hold, how easily air can flow through the filter, and how long the filter can be used before servicing. If one particular brand of filter consistently achieves 99%+ efficiency, it would be interesting to know if they also excel in the other performance areas, or are sacrificing one statistic to help increase another.
 
Perhaps air filter efficiency is not published because dry air filter efficiency is not constant. Initial efficiency with a new filter is the lowest and it improves as the filter is used, up to the design differential pressure. So if you change out your filter at 12000 miles or 1 year as many manufacturers recommend, then your realized efficiency is lower than if you run it out to the recommended DP. Any published efficiency number would have to specify whether is was initial, average or final and then the manufacturer would be liable to recommend a filter life that might reach the published efficiency number. Filter life without a "Filter Minder" gauge is tough to determine because ambient dust loading can vary by several orders of magnitude. I still do not understand why all vehicles are not equipped with "Filter Minders" from the factory but you can retrofit most vehicles with a gauge and it will save you money in filter changes and extend the life of your engine. A win-win situation.
 
Originally Posted By: wemay
From K&N...

https://www.knfilters.com/faq.htm#5


99% filtration efficiency is certainly a very good achievement. However, filter efficiency is just one statistic of filter performance which is measured (but is also the statistic most commonly published). The other air filter performance statistics measured are: capacity, restriction, and service life. These other factors reflect the amount of dirt the filter can hold, how easily air can flow through the filter, and how long the filter can be used before servicing. If one particular brand of filter consistently achieves 99%+ efficiency, it would be interesting to know if they also excel in the other performance areas, or are sacrificing one statistic to help increase another.


Indeed it is interesting.

As a defence, though, (sounds defensive to me, anyway) its weakened a bit by the (only?) available comparative study using ISO 5011, which shows the KnN filter tested to be worst or 2nd worst on ALL these parameters except maximum flow rate, which was in excess of anything likely to be needed or useable.

http://www.nicoclub.com/archives/kn-vs-oem-filter.html
 
Originally Posted By: compratio10_5
Perhaps air filter efficiency is not published because dry air filter efficiency is not constant. Initial efficiency with a new filter is the lowest and it improves as the filter is used, up to the design differential pressure. So if you change out your filter at 12000 miles or 1 year as many manufacturers recommend, then your realized efficiency is lower than if you run it out to the recommended DP. Any published efficiency number would have to specify whether is was initial, average or final and then the manufacturer would be liable to recommend a filter life that might reach the published efficiency number. Filter life without a "Filter Minder" gauge is tough to determine because ambient dust loading can vary by several orders of magnitude. I still do not understand why all vehicles are not equipped with "Filter Minders" from the factory but you can retrofit most vehicles with a gauge and it will save you money in filter changes and extend the life of your engine. A win-win situation.


I understand what you're saying, but that's the point of ISO 5011. It addresses, among other things, the efficiency rating of air filters. This rating would be valuable to know.
 
...and even in that nicoclub study, K&N finished with 96.8% efficiency. The graph bars make it look much worse than the actual numbers.
 
Originally Posted By: wemay
...and even in that nicoclub study, K&N finished with 96.8% efficiency. The graph bars make it look much worse than the actual numbers.


IIRC, the Donaldson PowerCore is 99.98% or something insane. So while I wouldn't necessarily describe the 96.8% as "awful", there are significantly better filters available, many (most?) of them which primarily focus on big breathers like Diesels.
 
Originally Posted By: wemay
...and even in that nicoclub study, K&N finished with 96.8% efficiency. The graph bars make it look much worse than the actual numbers.
I don't think so. They're tricking you into looking at the significant numbers backwards. 3.2% (=100%-96.8%) of dust getting through is 3.2 times worse than (for example) 1% (=100%-99%) getting through. Even 1% would be too much, if it's ordinary silica dust. We need more detail on the test method.
 
Yes, CR94 is right. You need to compare how much dust is passing through the filter when making comparisons. Penetration = 1-efficiency so:
1-0.99= 0.01
1-0.98= 0.02 (twice the wear rate)
1-0.97= 0.03 (3 x the wear rate)

So small changes in efficiency can have a large effect on engine wear rate. I too would like to know more about filter performance but the manufacturers do not cooperate for us light duty folk. SAE paper #952557, "Total Filtration: The Influence of Filter Selection on Engine Wear, Emissions, and Performance" contains figure 7 which indicates that engine wear decreases by a factor of 10 from a new air filter to a well used air filter. This paper was written by Marty Barris of Donaldson Company pertaining to heavy duty (Diesel) engines but I believe that it applies to light duty engines as well.
 
As a layperson (99.9% of consumers are) 99% to 96.8% is a very small difference in the case of this filter. I'm not going to extrapolate and disect those numbers to glean anything more than that. I've seen other paper filters say less than 95% (current STP in my Santa Fe, for instance, says 90% efficiency). And I've seen K&N have higher than 96% too. As with many topics on BITOG, we'll just agree to cordially disagree. The K&N option will not ruin your vehicle and is a viable choice for many.
 
For me, the K&N idea has somewhat outlived its usefulness. As I've posted before, I've used them in the past, and quite gladly. When air boxes were that junky and sitting above a carb, and filters had some pretty pathetic build quality, they were a viable option. When I had my Town Car with the new fangled (at the time) square filter box and those filters cost a pile of money, a K&N that could go for 100,000 km before being cleaned, and ten times that before being replaced, was a very attractive option.

Now, with the G37, and me being able to toss on two filters every couple years at $12 or so a piece, and some well built stuff, it's not so bad.
 
Completely understand, Garak. That point of view has it's merits. The air filter for my Sonata costs $20. I picked up the K&N for $65. To me, getting the K&N was worth it. But i know it isn't so for everyone.
 
Originally Posted By: compratio10_5
Yes, CR94 is right. You need to compare how much dust is passing through the filter when making comparisons. Penetration = 1-efficiency so:
1-0.99= 0.01
1-0.98= 0.02 (twice the wear rate)
1-0.97= 0.03 (3 x the wear rate)



However you define "wear rate" (which you havn't) I doubt it'll be simply, directly and linearly related to the % efficiency like that. The dust passing the less efficient filters is probably qualitatively different, (for example, its likely to be coarser) so may have different wear effects.

They also measured the total passed until the restriction guage tripped, 7 g for the K+N, or 17.5X more than the ACDelco at 0.4 g
 
I am simply reporting what was reported in SAE Paper #952557, that was written by Marty Barris of the Donaldson Company. As one of the major heavy duty filter manufacturers in the world, I trust their reported wear models which are based on research and presumably their own experience. Here is the quote from the Intake Air Filter Related Wear- Air Wear Model:
"Numerous studies support the correlation between air intake ingested particles and engine wear (11 sources cited). The recent study by Treuhaft (SAE #930019) concluded that a well defined linear relationship exists between dust concentration and engine wear rate using the radioactive tracer technique for piston rings."

Regardless of the exact accuracy of the models, this and many other studies reinforce the importance of minimizing intake air dust ingestion by using filters that have the highest initial efficiency,and by utilizing the entire design life since efficiency of dry air filters improve with loading. In the example above, the K&N filter will result in 17.5 times more engine (ring) wear than the ACDelco filter using the Donaldson Company Total Filtration Model.
 
Originally Posted By: wemay
99% to 96.8% = 3.2% difference.
1% vs. 3.2% not captured = 220% more dirt reaching the rings.
 
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