K&N test Here it is again___GB
The filtration report generated by Mr. Arlen Spicer in 2004 (
http://home.stny.rr.com/jbplock/ISO5011/SPICER.htm) has received a great deal of attention over the past few years. The report was prepared for members of Dieselplace.com, a diesel enthusiast forum, and has circulated among other online communities. In his report, several brands of air filters were subjected to a side-by-side comparison test of their dust holding capacity, filtration efficiency, and restriction. Testand Corp. of Rhode Island offered to complete the testing for Mr. Spicer’s report at no charge. K&N is aware of Mr. Spicer’s report and its findings. The data collected from the K&N filter in Mr. Spicer’s report was unusually low and did not correlate with test data gathered by both independent and in-house testing. In 2006 we contacted Mr. Spicer and invited him to visit K&N’s headquarters in Riverside, CA to discuss the results of his report.
Mr. Spicer visited K&N in 2006, and during his visit, Mr. Spicer along with K&N employees tested a K&N air filter and its equivalent paper air filter replacement in K&N’s in-house filtration test lab. These tests were conducted using ISO 5011 protocol, which can be viewed at
http://www.knfilters.com/efficiency_tes ... cedure.htm. There were differences between the test procedure used by K&N and the test procedure used in Mr. Spicer’s 2004 test, and the test results each procedure yielded. The significant differences were:
• Cumulative efficiency of the K&N filter improved from 96.8% in Mr. Spicer’s report to 98.74% in testing performed while Mr. Spicer was visiting K&N.
• Dust holding capacity of the K&N filter improved from 211 grams in Mr. Spicer’s report to 276 grams in testing performed while Mr. Spicer was visiting K&N.
• Cumulative efficiency of the paper filter decreased from 99.93% to 99.57% in the test performed at K&N while Mr. Spicer was present.
• Dust holding capacity of the paper filter increased from 573.9 grams to 792.84 grams in the test performed at K&N while Mr. Spicer was present.
• In the test performed at K&N while Mr. Spicer was present, the initial efficiency of the paper filter tested to be 98.25% and the initial efficiency of the K&N filter tested to be 98.17% (only .08% difference). Mr. Spicer’s test does not state what initial efficiencies were for any of the filters tested.
• Dust feed rate during the K&N test was 0.25 grams per cubic meter for the first 60 grams of dust fed, then 1.0 grams per cubic meter until the termination of the test. Mr. Spicer’s test used a constant dust feed rate of 1.0 grams per cubic meter for the entire test. Both dust feed methods are ISO 5011 compliant, but can yield different test results.
• Testing conducted by K&N is considered to be “constant flow” meaning the duration of the test is conducted at a set air flow rate. Mr. Spicer’s test was a “variable flow” test, meaning the test is started at an initial air flow rate which will be the maximum rate for the test, and then at specified intervals the flow will be varied by a certain percent. Both flow methods are ISO 5011 compliant, but can yield different test results.
Mr. Spicer wrote a follow-up report after his visit to K&N, and posted it on the Dieselplace.com forum. The follow-up report can be viewed at
http://www.dieselplace.com/forum/showthread.php?t=66536. Mr. Spicer made certain statements in his follow-up report, which K&N feels obligated to comment on.
1. Spicer: “So, according to lab work compliant to ISO 5011, the K&N product showed performance that was significantly improved over the Testand results. So, which results are more accurate, the K&N and Southwest Research results or the results in our study? The answer to this question is not an easy one. Essentially, the results of the K&N lab results and Testand’s results are both valid and at the same time cannot be directly compared for many reasons.”
K&N: Mr. Spicer has mentioned that the K&N filter’s efficiency significantly improved over his test, but does not comment on the fact that the paper filter’s efficiency was nearly the same. Mr. Spicer also does not comment on the impact the “many reasons” can have on a test’s results, a topic which was discussed during his visit to K&N. Many of these “reasons” are “options” which are built in to the ISO 5011 test protocol for the test technician to choose, and these reasons can directly impact how a filter loads with dust.
2. Spicer: “K&N tested the filters under a much lower initial dirt feed rate of 0.25g/cu. meter for the first 60 grams of dirt and then completed the test at 1.0g/cu. meter for the remainder of the test. Testand, on the other hand, ran the entire test at 1.0g/cu. meter (9.8g/minute at 350 cu. ft/ minute). The implications of this may be speculative, but I would have to conclude that a slower initial feed rate to a clean filter could improve it’s initial efficiency%. This would lead to an improved overall filtering efficiency when compared to a filter tested under a more demanding initial feed rate as was the case with the Testand testing.”
K&N: If what Mr. Spicer claims about dust feed rates were true, why did the efficiency test results of the paper filter change very little, but the K&N change so dramatically? The answer to this lies in the options selected for each filter for Mr. Spicer’s test. K&N uses a slower dust feed rate during the initial phase of the test because a faster feed rate could prematurely plug the filter, maintaining a higher efficiency for the duration of the test. This theory is supported by comparing data from Mr. Spicer’s original test to the test performed while he was at K&N. The paper filter passed more than twice the amount of dust during the initial phase of the K&N test (at the lower feed rate) than during Mr. Spicer’s full life test at a higher feed rate.
3. Spicer: “With variable flow testing the filter experiences a continuous change in differential pressure resulting in a “capture and then release” of the dirt particles within the test media. According to an independent testing facility, variable flow testing is a more challenging test for filter medias and will commonly result in significantly lower efficiency numbers.”
K&N: The idea that varying air pressure can dislodge dust particles from an air filter is significant, but only when discussing dry paper filter media. Oiled media does a very good job of keeping captured dust in place in the filter, unless outside force is applied to knock it loose, and Mr. Spicer was able to observe this during his visit to K&N. Think of oiled media as “fly paper”. The oil is the sticky substance which traps foreign objects and holds them in place. How well would fly paper work without its stickiness? If Mr. Spicer’s theory of the effect of pressure change was valid, the efficiency of the paper filter should be significantly different in his own test (variable flow) vs. the test conducted at K&N (constant flow). But they were not.
4. Spicer: “The Testand test employed variable flow testing. The K&N test employed constant flow testing. Again, both test are ISO 5011 compliant. However, given the differences in testing methods the two results are in no way directly comparable.”
K&N: Mr. Spicer is correct; the test results for each testing method are not directly comparable. However, our experience in operating a full-time testing lab has shown us that many times the outcome we thought would happen or seemed logical, was in fact a misconception. There are many misconceptions which can be uncovered by comparing and contrasting Mr. Spicer’s original test to the test performed while he visited our lab. The overall purpose of ISO 5011 testing is not to establish a letter grade or minimum standard for air filtration efficiency, and to K&N’s knowledge such an Industry standard does not exist. ISO 5011 was written to standardize the procedure used to run the test. When two testers select different options in their testing procedures, the outcomes can be compared to determine how the selection of a particular variable affected the test outcome.
A proper question that would come up to the person who really reads this would be “why did K&N test filters using constant flow if the Spicer tests used the variable flow option”? Answer is according to the Spicer report
http://home.stny.rr.com/jbplock/ISO5011/SPICER.htm on the first page under the heading Capacity and Efficiency: it states “The Capacity and Efficiency test report presents the test results of feeding an initially clean filter with PTI Course <sic> Test Dust (dirt) at a constant rate and flow.” Later in the sentence it mentions “constant airflow” again. It was not discussed until later that Testand Corp. used the variable option and we were unable to verify exactly what schedule was used.
K&N addressed these questions to Mr. Spicer in an email, since the report he wrote of his visit did not reflect the knowledge of filtration testing we thought he took home with him. Mr. Spicer acknowledged receiving our email in a post on the Dieselplace.com forum (the post can be viewed here:
http://www.dieselplace.com/forum/showpo ... stcount=32) but we were unable to satisfactorily resolve the issues.
