Air Filter Testing
Preliminary Report
Michael Woods
Webbsair Ltd
(Boreas Air)
Dr. Thomas Dooley CREDIT
School of Engineering
DkIT
December 15, 2015
1 Introduction
The performance of air filters is critical to the efficient operation of a wide range of equipment from
heavy rock crushers to the standard vacuum cleaner. This report reviews the testing of air filters, out
lines a campaign of field testing on a new patented product improvement for air filters and examines
the economic advantage of this new process.
The report relies of Field testing to measure the difference between the product improved and the
standard filter. Field tests have the advantage of taking into account the real operation of the equipment in its normal environment which includes the effects of climate, vibration and also environmental
dust levels.
There are also standard laboratory tests which offer a baseline comparison on laboratory conditions
between various filters available on the market.
There are three basic ways to measure the differences between air filters or in this case to check if
retrofitting with Boreas Air improves filter quality and efficiency. The first way and a clear industry
standard is a test of filtration efficiency ISO 5011 [1](formerly SAE J726).
1.1 Filtration Efficiency
The ISO 5011 is a test procedure or protocol with built in options. In order to compare two ISO
5011 test results, you need to understand which options have been selected. The test measures the
Percentage of dust retained by an air filter as the dust is introduced into a stream of air
flowing through the air filter at a constant rate. There is both an initial measurement and an
overall measurement, both of which will be percentages. For example, a filter efficiency result of 95%
means that the air filter retained 95% of the test dust allowing 5% to be passed through the air filter.
The particle size and mix of the test dust itself is specifically defined by an ISO standard. For most
applications, coarse test dust is used and is comprised of a precise mix of particles ranging in size from
5.5 microns to 176 microns. By way of comparison, a human hair width is approximately 50 microns,
so even coarse test dust includes a significant amount of microscopic particles. Some companies design
their own dirt test to save the money of doing it right, but there is only one generally accepted
standard test procedure and that is the ISO 5011. K and N Air Filters for example tested generally
range between 96% and 98% in overall efficiency using coarse test dust.
1.2 Capacity
The second test of air filter capabilities is also measured using the ISO 5011 test procedure and
is called capacity.
Capacity results show how much dust the air filter can retain before
reaching a predetermined point of air flow restriction, generally held to be harmful to
engine performance and life.
Capacity is generally conveyed in grams and is impacted by several
variables such as the technical performance of the filtration medium, the physical amount of filtration
medium present, and size of the air filter itself.
As an example, an air filter with a dust capacity of 250 grams means it will hold that much dust before
cleaning or replacement is necessary.
Individual air filters can have capacity as low as 100 grams or as high as 1000 grams. K and N air
filters are designed to have enough capacity to provide a service life of up to 50,000 miles for O/E
replacement filters or up to 100,000 miles for large universal conical filters
1.3 Restriction
The third test historically overlooked by the entire disposable air filter industry is the amount of restriction created by the filter medium.
Higher restriction means more engine effort is required to provide the engine with one of the four critical components of combustion. Air!
Use a flow bench and increase the rate of airflow until restriction equals a pressure drop sufficient to
displace 37.5 mm of a consistent quantity of water.
1.4 Extract Section 6 ISO 5011
Performance tests shall be performed on a complete air cleaner assembly or on a single air cleaner
element; tests on a complete air cleaner assembly are preferred. The tests shall consist of an air flow
Restriction/differential pressure test, an efficiency test and a capacity test. In addition, a pressure
collapse test shall be performed on the air filter element.
Restriction Test The purpose of this test is to determine the restriction/differential pressure/pressure loss across the unit under test which will result when air is passed through under
Predetermined conditions. Airflow restriction or differential pressure is measured with a clean filter
element
Efficiency test.
The purpose of this test is to determine the retention capabilities of the unit under test.
This test can be conducted with either constant or variable air flow and with coarse dust or fine test dust.
If desired, efficiency tests can be performed concurrently with capacity tests (see 6.5).
Determination of the efficiency at constant test air flow can be performed at the rated air flow or any percentage thereof, as agreed upon by the user and manufacturer.
Determination of efficiency at variable air flow can be performed using variable air flow cycle according to 6.7.
Capacity test.
The purpose of this test is to determine the total mass gain of the unit under test at the terminating condition.
This test can be conducted with either constant or variable air flow and with coarse or fine test dust contaminant.
If desired, the capacity determination can be performed concurrently with the efficiency test (see 6.4).
Filter element pressure collapse test.
The purpose of this test is to determine the ability of an air filter element to withstand a specified differential pressure and/or to determine the differential pressure at which collapse occurs.
2 Comparative ISO5011 tests Diesel Forum USA
Reproduced below is a test campaign by some USA diesel enthusiasts.
It is informative in that they commissioned a testing lab to investigate claims for a range of filters and then published the results on their forum.
In essence the process they used can be adopted for our testing campaign with different retrofitted
filters.
On a diesel forum posted in July 2004 [?] the members banded together to conduct an independent study regarding air filters for the Duramax Diesel. They claim that there is is a lot of marketing hype surrounding certain aftermarket air filters and they wanted to know if the filters could standup to their claims.
Claims of ”superior” filtering ability and dirt holding capacity are among some of these claims. Additionally, many filters are claimed to allow for ”better” air flow giving you more horsepower.
This claim of better flow giving more horsepower is a debate all its own, but dyno tests run with a
paper filter vs. NO FILTER AT ALL have shown NO INCREASE IN POWER OUTPUT.
Therefore a filter with ”better flow” will not only give you no increase in performance, it will also let in a lot of
dirt while doing it.
The following data is provided by Testand Corp. in Rhode Island. Testand makes the $285,000 machines that perform the SAE J726/ISO 5011 air filter test standard. Any air filter that wants to be tested for performance and efficiency uses this test.
These tests cost $1,700 per filter when done by an independent laboratory. Testand Corp. was interested in the comparison study and agreed to do the study for us.
Every filter listed was tested in an identical manner according to the SAE/ISO 5011 test standard;
Here are the results:
In the order of EFFICIENCY (ability to filter dirt) the results are as follows: FLOW RESTRICTIONS
Table 1: Efficiency
FILTER % EFFICIENCY
AC Delco OE 99.93%
Baldwin paper 99.72%
No name pargain paper 99.32%
AFE Pro Guard 7 panel filter 99.23%
WIX/Napa Gold 99.03%
Purolator paper 98.73%
Amsoil, new style 98.63%
UNI 97.93%
KandN 96.80%
Remember, 27.7 inches of water = 1 psi. So, 1 inch of water = .036 psi.
The worst (AC Delco) at 6.23 in. water and the best (KandN) at 4.54 in. water is a difference of 1.69
- of water or a”whopping” .0608 psi. Virtually negligible.
In order from least restrictive to most:
DIRT HOLDING CAPACITY. From best to worst. This is the AMOUNT of test dirt it took to
create an ADDITIONAL 10 inches of restriction. At that point the test is terminated.
This is an indication of HOW LONG a filter is good before it must be cleaned or replaced.
TOTAL DIRT PASSING THE FILTER DURING THE TEST. This is how much dirt your engine
will take in if you use the filter for the duration that would cause the filter to become ”dirty” enough
to need replacement or cleaning. The ”Dirt Passing The Filter” is the dirt collected by the ”POST
FILTER” during the SAE/ISO test.
In order from best to worst, the filters performed as follows:
Table 2:
Restriction Inches of Water
FILTER RESTRICTION in inches of water
KandN 4.54
Mystery bargain 4.78
AFE Pro Guard 4.99
Purolator 5.05
WIX/Napa Gold 5.06
UNI 5.40
Baldwin 5.71
Amsoil 5.88
AC Delco 6.23
3 IBR testing facility
From: Susan Goldsmith [mailto:sgoldsmith@ibr-usa.com] Sent: 23 October 2015 11:57 To: Thomas Dooley
Cc: David Wright Subject: Re: Contact Form Submission: ISO 5011 Filter testing
Hello Tom- Thanks for contacting IBR. The ISO 5011 is within the scope of accreditation for IBRs
USA lab. I have copied David Wright, IBR USA Air Lab Supervisor. He will be able to assist.
Will these be panel or cylinder filters? Do you have the air box (housing)? The full Air Induction
System? Or is this filter media alone? Will you want steady flow or cycling? For R and D, steady is more common.
Thanks very much Susan
Susan Goldsmith Managing Director IBR Laboratories + 1 517 522 8453
CONFIDENTIAL This communication is for use by the intended recipient and contains information that may be privileged, confidential or copyrighted under applicable law. If you are not the intended recipient, you are hereby formally notified that any use, copying or distribution of this email, in whole or in part, is strictly prohibited.
Please notify the sender by return e-mail and delete this e-mail from your system. Unless explicitly stated otherwise ,the views expressed in this e-mail are those of the individual sender.
On Oct 23, 2015, at 4:23 AM, Dr Thomas Dooley ¡thomas.dooley@dkit.ie¿ wrote:
From: Dr Thomas Dooley ¡thomas.dooley@dkit.ie¿ Subject: ISO 5011 Filter testing Channel: IBR Europe
Company: CREDIT Dundalk Institute of Technology Ireland Phone: 0035342700200
Message Body:
I am looking for a quotation to test air filters for efficiency, capacity and restriction to ISO
5011 for a client who has commissioned our research centre (CREDIT) in Dundalk Ireland regarding an air filter design improvement.
Regards Tom
– This mail is sent via contact form on IBR-USA – http://ibr-usa.com/
Table 3: Capacity
Dust holding Capacity
AC Delco 573.898 g
WIX/Napa Gold 447.366 g
Purolator 388.659 g
Baldwin 388.154 g
UNI 374.638 g
Mystery bargain 350.402 g
AFE Pro Guard 7 232.516 g
KandN 211.580 g
Amsoil 196.323 g
4 Field Testing
Field testing was arranged at two sites as per letters in appendix A attached.
The purpose of the field tests is to comparatively determine the filtration efficiency and capacity of wrapped versus unwrapped filters.
Efficiency test
The purpose of this test is to determine the comparative retention capabilities of the units under test.
This test is conducted in the operating environment with the actual air flow and environmental dust conditions.
Capacity test
The purpose of this test is to determine the comparative total mass gain of the unit under test at the terminating condition. The capacity determination is performed concurrently with the efficiency test.
The tests were carried out on four filters in Test site ‘A’ in the Roadstone quarry, Duleek Co Meath, beginning in November 2015.
The Filters are numbered and described as follows:
- Filter ID. 01 Wrapped on PowerScreen 27
- Filter ID. 02 Unwrapped on TESAB32 623C
- Filter ID. 03 Wrapped on Pegasus
- Filter ID. 04 Unwrapped on PowerScreen 5103
Figure 1: PowerScreen Crusher at Duleek Quarry
Figure 2: Filter Location
Figure 3: Filter in Housing
Figure 4: Filter removed
Figure 5: Filter with Dust layer on Wrapping prior to weighing
Figure 6: Filter being weighed
Figure 7: Filter No.2 Removal
Figure 8: Filter No.2 after Removal- No Wrapping
Figure 9: Filter No.2 being weighed
Figure 10: Field Data Recorded Filter ID 03
Table 4: Capacity 2
FILTER DIRT IN GRAMS PASSED
AC Delco 0.4g
Baldwin 1.1g
AFE Pro Guard 7 1.8g
Mystery bargain 2.4g
Amsoil 2.7g
WIX/Napa Gold 4.4g
Purolator 5.0g
KandN 6.0g
UNI 7.9g
5 Case Study TESAB32 623C mobile rock crusher.
Table 6: Maintenance Costs and Savings (52 weeks) TESAB
Costs using washed filters $ 97,744.50
Costs Using new filters $ 97,654.50
Costs Using Boreas Air $7,312.50
Saving over washed filters $ 90,432.00
Saving over new filters $ 90,342.00
The Savings achieved using, Boreas Air per hour are quite dramatic.
The saving over washed filters is $ 10.35 per hour
The saving over new filters is $ 10.34 per hour
5.1 Komatsu Dozer
A similar exercise was repeated for a Komatsu.
Table 7: Maintenance costs breakdown –Komatsu
Table 8: Maintenance Costs and Savings (52 weeks) Komatsu
Costs using washed filters $ 4,925.68
Costs using new filters $ 4,745.68
Costs Using Boreas Air $ 3,145.50
Saving over washed filters $ 1,780.18
Saving over new filters $ 1,600.18
6 Field Test Results
The field testing began on 10/11/2015 in Roadstone Duleek Quarry Co Meath. The tests were carried out on four filters as follows:
- Filter ID. 01 Wrapped on PowerScreen 27
- Filter ID. 02 Unwrapped on TESAB32 623C
- Filter ID. 03 Wrapped on Pegasus
- Filter ID. 04 Unwrapped on PowerScreen 5103
Each filter was weighed and its mass recorded as follows
- Filter ID. 01 Wrapped 1662 g unwrapped 1627 g
- Filter ID. 02 Unwrapped 4252 g
- Filter ID. 03 Wrapped o 4429 g unwrapped 4360 g
- Filter ID. 04 Unwrapped 672 g
When the filters were cleaned which only occurred for the unwrapped filters and was carried out by site operatives they were reweighed before being reinstalled and the retained dust mass recorded.
The Wrapped filters were also weighed before being rewrapped.
The last sets of results available are for December 2nd.
The trend is fairly clear in that the wrapped filters are retaining the dust on the outer layer and it is not penetrating into the core of the filter.
There is also evidence that the vibration of the machinery is displacing dust from the surface of the wrapped filter.
Where the graphs return to zero dust retained around 24/11 is when the unwrapped filters are cleaned or wrapped filters re-wrapped. Figure (11) shows that the unwrapped filter is retaining more dust than the wrapped filter.
The wrapped filter is not allowing the dust into the core of the filter and the vibration of the machinery is removing the dust cake from the wrapping. Therefore the life of the filter is being prolonged.
Figure (12) shows that the unwrapped filter is again is retaining more dust than the wrapped filter.
The wrapped filter is not allowing the dust into the core of the filter and the vibration of the machinery
is removing the dust cake from the wrapping even more so than in the previous figure.
Therefore the life of the filter is being prolonged.
7 Conclusion
The retro -fitting of an existing air filter with Boreas Air will have an effect on all three numbers namely
efficiency, capacity and Restriction.
From the field testing so far it would appear that the retrofitted filter has increased filtration efficiency and capacity.
I would hypothesize but tests would need to confirm that for new filters just in service, it will restrict air flow not least because of an additional layer albeit of benefit in the long term. This is not measured in the present field tests.
I would also hypothesize and again for new filters just in service that it will increase restriction in that the extra layer will contribute to a slightly higher pressure drop since the air will find it more difficult to flow, but as previously stated the long term benefits will outweigh this.
The Field tests so far demonstrate as the filter advances through its service life the air flow restriction for the unwrapped filter increases, thus restricting air flow.
The comparative air flow restriction visible in Figures (11) and Figure (12) between a wrapped filter with low dust penetration and quantity at its core is clearly better than the equivalent unwrapped filter.
The major quantitative conclusion from the tests so far is that the wrapping increases the efficiency and capacity of the filters and would seem to improve flow restriction by decreasing the resistance to air flow as the filter advances through its service life.
While the ISO 5011 tests as carried out by IBR will also give us figures for the efficiency, capacity and Restriction these results are very much restricted to the standard benign environmental conditions of the laboratory.
The Field Tests are more informative in that they give clear indications of comparative performance in the industrial environment.
References
[1] Saso Iso. Inlet air cleaning equipment for internal combustion engines and compressors –
Performance testing. 2007.
