Scope and Application
K&N Filters performs air filter tests for efficiency and capacity in compliance
with the ISO-5011 Standard for Performance Testing of Inlet Air cleaning
equipment for internal combustion engines and compressors. Previous to the
adoption of the ISO-5011, testing was performed in compliance with the SAE J-726
- Air Cleaner Test Code. The ISO standard states that the basic performance
characteristics of greatest interest are air flow restriction, dust collection
efficiency, and dust capacity. K&N adheres to the ISO standard in the
measurement of these test parameters.
 Lab Environmental Conditions
K&N maintains the ISO Filtration Lab at 70° F and 50% RH within the limits of the ISO standard for normal testing.
Calibration and Equipment Checks
Check Lab conditions each morning to verify they are stable and within the
prescribed limits. Verify that the dampers are open and operate the system air
blowers at a predetermined rate. Monitor computer data channels to ensure that
all instruments are working properly. Verify that the digital cameras are
charged and operational.
Allow test dust to acclimate to lab conditions for 24 hours and load the
necessary  amount into the dust feeder hoppers for the first test to be
performed.
Set the weighing oven to 105°C (221°F) and allow it to come up to operating
temperature.
Periodically - Validate the efficiency of absolute filter media as required by
the ISO standard. Calibrate instrumentation periodically as required by the
calibration schedule.
Test Fixtures
K&N uses three types of fixtures to enable testing of the broad types, shapes
and sizes of the filter we manufacture. For OEM replacement filters we have
found that using the OEM air box or filter housing allow the best comparison and
repeatability when testing these filters. Another type of fixture used is a
filter housing conforming to the design specifications spelled out in the ISO
5011 protocol.  This ISO Fixture is used for specific testing as specified by the
engineering staff as well as for most round filters. Lastly, K&N has developed a
cabinet type of fixture, modeled after the ISO fixture for testing universal
clamp-on type filters. This cabinet allows repeatable consistent dust loading of
these open element type filters.
Once the test fixture has been specified, the Dust Test procedures are the same for
all filter types except for some minor differences in mounting, orientation and
placement of the dust nozzle and pressure taps which become apparent when
finalizing the setup of the test apparatus.
Lab Test Procedures
Condition and Restriction Test - Verify that the dust feeder has been loaded with the proper amount and type of dust for
the test to be performed.
Install a new absolute filter into the test stand filter tray. Condition the
absolute filter at 110% of the rated flow of ambient air for 15 minutes to
reduce any subsequent errors in measurements caused by losses of fibers or
materials. The conditioning of the absolute filter can be performed in the
Manual Test Mode.
While performing absolute filter conditioning, prepare test data sheets and
other required documentation, mark test articles with appropriate task number,
photograph test articles and create test folder on the appropriate server as
required. Record the test information into the control computer and create the
necessary data file in the appropriate folder.
 Install
the test article (fixture) onto the test stand specified in the test request.
The connections for the upstream and downstream pressure measurements are made
using the two tubes marked Test Filter Restriction and Test Filter Delta-P. The
tubes are connected depending on the fixture to be used as follows:
ISO Housing or Dust Cabinet – Install the tube marked Test Filter Restriction to
the dust cabinet outlet tube pressure port (clean side of the filter). Install
the tube marked Test Filter Delta-P to the dust feed tube pressure port (dirty
side of the filter). Attach grounding cables to test fixture and test article as
recommended by the ISO test standard.
OEM
Air box - Install the tube marked Test Filter Restriction to the upstream
absolute filter pressure port of the test stand plenum. Leave the tube marked
Test Filter Delta-P open to atmosphere. Attach grounding cables to test stand
and test article as recommended by the ISO test standard.
Perform the Condition and Restriction Test using test filter and absolute filter
at the air flow rate specified by the test request. Condition the test apparatus
for 15 minutes as required by the ISO standard. Measure and record the
restriction and differential pressure versus flow rate at 50%, 75%, 100%, 125%,
and 150% of the requested air flow rate.
Measure
and record the mass of the test article and dust chamber (fixture). Stabilize an
absolute filter using the ventilated oven at the required temperature. Measure
and record the mass of the absolute filter.
Reinstall the absolute filter and test article with fixture into the appropriate
test stand. Re-attach grounding cables to test fixture and test article as
recommended by the ISO test standard.
Initial Efficiency Test
The purpose of the Initial Efficiency Test is to determine the dust retention
capability of the test article when loaded with an initial amount of test dust.
The initial efficiency will be determined after the addition of 20g of dust or
the number of grams numerically equivalent to 6 times the air flow in m3/min
(cubic meters / minute), whichever is greater. Using the appropriate worksheet,
determine the actual number of grams to be applied in the initial efficiency
test based on requested flow rates and enter the appropriate amounts including
the termination criteria into the control computer. Enable the control computer
to record all necessary data parameters for the duration of the test.
At
the Lab computer interface, lock in the scale reading by checking the
appropriate dialog box. Switch on the blower and verify that it reaches the
required test air flow rate and allow the system to stabilize. Turn on the dust
feeder using the dialog box control button and record the initial restriction
(delta-p).
Monitor the system parameters until the termination point has been reached. The
control computer will automatically shut down the blower and dust feeder at the
termination point. Record screen data on the appropriate data sheet and file it
in the test folder.
Remove the test filter, fixtures and the absolute filter from the test stand.
Photograph the test article and fixtures, and note any anomalies in the comments
section of the datasheet. Place the absolute filter in the ventilated oven and
periodically check for the weight to stabilize. Record the final absolute filter
weight on the data sheet.
Weigh the test filter and fixture. Record the weight(s) on the appropriate data
sheet. If the test filter reached its full-life termination pressure during the
initial test phase, record that fact in the data sheet and archive the test
filter, otherwise prepare the test filter and fixtures for the
full-life/capacity test.
Full-Life/Capacity Test
The purpose of the Full-Life/Capacity Test is to determine the total mass of
dust retained by the test filter by recording the incremental weight of the dust
fed until the test filter reaches a terminating pressure restriction as
specified by the test request.
The full-life efficiency will be determined after adding a quantity of dust at
the rate of 1 g/m3 (grams per cubic meter) until the test filter reaches a
predetermined pressure restriction. Enter the air flow rate, dust feed rate, and
termination pressure into the control computer dialog box. Set the control
computer to record all necessary data parameters for the duration of the test.
Reinstall the absolute filter, test filter and appropriate fixture onto the test
stand. At the Lab computer interface, lock in the scale reading by checking the
appropriate dialog box. Switch on the blower and verify that it reaches the
required test air flow rate and allow the system to stabilize. Turn on the dust
feeder using the dialog box control button and record the initial restriction
(delta-p).
Monitor the system parameters until the termination point has been reached. The
control computer will automatically shut down the blower and dust feeder at the
termination point. Record screen data on the appropriate data sheet and file it
in the test folder.
Remove
the test filter, fixtures and the absolute filter from the test stand.
Photograph the test article and fixtures, and note any anomalies in the comments
section of the datasheet. Place the absolute filter in the ventilated oven and
periodically check for the weight to stabilize. Record the final absolute filter
weight on the data sheet.
Weigh the test filter and fixture. Record the weight(s) on the appropriate data
sheet and archive the test filter.
Appendix A: Equations and Formulas
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