ISO 11155-2:2009

INTERNATIONAL ISO
STANDARD 11155-2
First edition
2009-01-15
Road vehicles — Air filters for passenger
compartments —
Part 2:
Test for gaseous filtration
Véhicules routiers — Filtres à air pour l'habitacle —
Partie 2: Essai pour le filtrage des gaz

Reference number
©
ISO 2009
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©  ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Measurement accuracy . 4
4.1 Flow rate . 4
4.2 Pressure. 4
4.3 Temperature . 4
4.4 Relative humidity . 4
4.5 Challenge gas. 4
5 General conditions . 4
5.1 Conditioning of challenge gas . 4
5.2 Cleanliness of influent air . 4
5.3 Challenge gas concentration stability. 4
6 Test contaminants . 5
6.1 Mandatory contaminants . 5
6.2 Optional contaminants. 5
6.3 Other contaminants. 5
7 Test equipment . 6
7.1 General layout . 6
7.2 Test stand performance . 6
7.3 Air supply . 6
7.4 Test duct . 6
7.5 Contaminant generation and supply . 6
7.6 Sampling and analysis of challenge gas. 7
7.7 Test equipment constituents. 7
8 Experimental determination of t , using t . 8
0 lag
9 Preparation of filter/filter element for testing . 8
10 Test methods. 8
10.1 Purpose. 8
10.2 Air pressure loss. 8
10.3 Preparation of challenge gases. 9
10.4 Determination of efficiency/breakthrough . 9
10.5 Determination of capacity. 9
10.6 Data and analysis. 9
10.7 Determination of desorption (optional) . 10
11 System validation . 10
11.1 Air flow uniformity . 10
11.2 Verification challenge gas stability (without test filter) . 10
12 Test report . 11
Annex A (normative) Test stand configuration. 12
Annex B (normative) Detailed definition and calculation of t and t . 13
0 lag
Annex C (normative) Capacity determination . 15
Annex D (informative) Conversion of test contaminant concentration units . 16
Bibliography . 17
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11155-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 7, Injection
equipment and filters for use on road vehicles.
This first edition of ISO 11155-2 cancels and replaces the ISO/TS 11155-2:2002, which has been technically
revised.
ISO 11155 consists of the following parts, under the general title Road vehicles — Air filters for passenger
compartments:
⎯ Part 1: Test for particulate filtration [Technical Specification]
⎯ Part 2: Test for gaseous filtration

iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 11155-2:2009(E)

Road vehicles — Air filters for passenger compartments —
Part 2:
Test for gaseous filtration
1 Scope
This part of ISO 11155 specifies a test comprising several methods for measuring the dynamic gas adsorption
of air filters in the passenger compartments of road vehicles. These laboratory test methods are applicable to
air filters that improve air quality by reducing concentrations of gaseous, odorous or hazardous components
from ambient or re-circulated air, or both, in the vehicle cabin. They provide a means of measuring air
pressure loss, as well as gas and vapour removal characteristics.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/TS 11155-1, Road vehicles — Air filters for passenger compartments — Part 1: Test for particulate
filtration
ISO 11841-1, Road vehicles and internal combustion engines — Filter vocabulary — Part 1: Definitions of
filters and filter components
ISO 11841-2, Road vehicles and internal combustion engines — Filter vocabulary — Part 2: Definitions of
characteristics of filters and their components
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11841-1 and ISO 11841-2 and the
following apply.
3.1
test flow rate
volume of air passing through the test duct per unit time
NOTE It is expressed in actual cubic metres per hour.
3.2
pressure loss
difference in static pressure measured upstream and downstream of the filter at a specified flow rate
NOTE It is expressed in pascals.
3.3
contaminant
unwanted constituent dispersed in air
3.4
concentration
quantity of one constituent dispersed in another
NOTE Contaminant concentrations are generally expressed as mass concentrations, i.e. mass of contaminant in
milligrams per cubic metre of air. However, when the contaminant is measured as a volume fraction, i.e. volume of
contaminant per volume of air (often in parts per million), it is necessary to convert the volume of contaminant into a mass.
Conversion factors are given in Annex D.
3.5
influent air
cleaned air used to dilute contaminants and produce the challenge gas
3.6
challenge gas
homogeneous mixture of influent air and contaminant used to challenge the filter
3.7
challenge gas concentration
ratio of the mass (or volume) of test contaminant per volume of influent air measured under specified
conditions
NOTE Contaminant concentrations are generally expressed as mass concentrations, i.e. mass of contaminant in
milligrams per cubic metre of air. However, when the contaminant is measured as a volume fraction, i.e. volume of
contaminant per volume of air (often in parts per million), it is necessary to convert the volume of contaminant into a mass.
Conversion factors are given in Annex D.
3.8
test contaminant mass
m
T
total mass of test contaminant to which the filter is exposed
NOTE It is expressed in milligrams.
3.9
influent concentration
C
homogeneous challenge gas concentration measured before (upstream of) the filter
NOTE Contaminant concentrations are generally expressed as mass concentrations, i.e. mass of contaminant in
milligrams per cubic metre of air. However, when the contaminant is measured as a volume fraction, i.e. volume of
contaminant per volume of air (often in parts per million), it is necessary to convert the volume of contaminant into a mass.
Conversion factors are given in Annex D.
3.10
effluent concentration
C
homogeneous challenge gas concentration measured after (downstream of) the filter
NOTE Contaminant concentrations are generally expressed as mass concentrations, i.e. mass of contaminant in
milligrams per cubic metre of air. However, when the contaminant is measured as a volume fraction, i.e. volume of
contaminant per volume of air (often in parts per million), it is necessary to convert the volume of contaminant into a mass.
Conversion factors are given in Annex D.
2 © ISO 2009 – All rights reserved

3.11
efficiency
ratio of the amount of contaminant removed or reduced by the filter relative to the amount exposed to it,
calculated as a percentage by
100CC−
()
E= (1)
C
where
E is efficiency,
C is the influent concentration,
C is the effluent concentration
3.11.1
1 min efficiency
efficiency measurement 1 min after time zero, t
3.11.2
2 min efficiency
efficiency measurement 2 min after t
3.11.3
5 min efficiency
efficiency measurement 5 min after t
3.12
time zero
t
calculated zero point based on the shape of the ramp-up curve of challenge gas breakthrough versus time
NOTE 1 See Clause 8 and Annex B.
NOTE 2 Once this curve is obtained, the t point can be found by calculation. All efficiency or penetration data are
calculated from the designated t .
3.13
start of test time
t
start
time at which the challenge gas is introduced into the test system
3.14
lag time
t
lag
time difference between t and t
start 0
NOTE See Annex B.
3.15
end of test time
t
f
time at which a user-specified efficiency (typically 5 %) or user-specified time is reached
3.16
total test time
duration of exposure of the filter to the challenge gas, beginning at t
3.17
capacity
m
c
mass of contaminant removed from the challenge gas stream by the filter during the total test time
NOTE It is normally expressed in milligrams.
3.18
desorption
release of previously trapped contaminants from a test filter
4 Measurement accuracy
4.1 Flow rate
The measurement devices shall be calibrated relative to the respective challenge or contaminant gases. Their
accuracy shall be within ± 3 % of the specified value.
4.2 Pressure
Differential pressure accuracy shall be within ± 2 % of the measured value.
4.3 Temperature
Temperature shall be monitored to within ± 0,5 °C accuracy.
4.4 Relative humidity
Relative humidity shall be monitored to within ± 2 %.
4.5 Challenge gas
Challenge gas measurement accuracy for n-butane, toluene and SO shall be ± 3 % of the measured value.
5 General conditions
5.1 Conditioning of challenge gas
The temperature of the challenge gas shall be (23 ± 3) °C and the relative humidity shall be (50 ± 2) %.
5.2 Cleanliness of influent air
The content of organic contaminants in the influent air shall not exceed the equivalent of a volume fraction of
–6
2 × 10 of total hydrocarbon. High efficiency particulate air (HEPA) filtration (see EN 779) is recommended
for the removal of particulate contaminants.
5.3 Challenge gas concentration stability
Influent concentration shall be maintained to within ± 3 % of the set point concentration for the duration of the
test.
4 © ISO 2009 – All rights reserved

6 Test contaminants
6.1 Mandatory contaminants
Mandatory test contaminants are chosen either because their presence at high levels signifies deterioration in
air quality or because they provide useful indications of performance for certain types of purification systems.
Mandatory contaminants, purities and concentrations are specified in Table 1.
Table 1 — Test contaminants
Concentration
Minimum purity
Test contaminant
Set point
c
%
Conversion factor
b
Volume fraction in parts per million
a
n-butane 99,5 80 ± 8 2,39
Toluene 99,5 80 ± 8 3,79
a
Included because it provides a useful and facile test for activated carbon-based adsorption systems. Butane could be of limited
value for systems that do not rely on activated carbon adsorption. In these cases, another test contaminant may be substituted.
b
See Annex D for calculation of conversion factors.
c
Allows conversion to milligrams per cubic metre at 23 °C and a barometric pressure of 101 kPa.

6.2 Optional contaminants
Tests using the optional contaminant are subject to agreement between customer and manufacturer.
Recommended contaminants, purities and concentrations are given in Table 2.
Table 2 — Optional test contaminant
Concentration
Minimum purity
Test contaminant
Set point
c
%
Conversion factor
b
Volume fraction in parts per million

a
SO 99,5 30 ± 3 2,64
a
Included because it can be used to represent the family of acid gases in determining the performance of carbon-based adsorption
systems.
b
See Annex D for calculation of conversion factors.
c
Allows conversion to milligrams per cubic metre at 23 °C and a barometric pressure of 101 kPa.

6.3 Other contaminants
See Annex D for other contaminants. The use of other gases could be of interest for dedicated applications.

Gases of interest shall be agreed between customer and manufacturer.
7 Test equipment
7.1 General layout
The test stand shall meet the requirements given in 7.2 to 7.7. An example of a test stand configuration is
given in Annex A. All parts of the system that come into contact with the challenge gas shall be chosen and
designed such that they are chemically resistant and errors due to adsorptive effects on part surfaces are
minimized. The test stand shall include equipment or apparatus for conditioning the air supply, flow
measurement, pressure drop measurement, contaminant injection, sampling and sample analysis.
The test stand/equipment should preferably be operated in a sub-barometric pressure mode, i.e. with the
fan/blower placed downstream of the test filter. This configuration prevents penetration of challenge gas into
the ambient atmosphere in case of equipment leaks. Furthermore, systematic errors due to the challenge gas
contacting the fan unit are excluded. Although operation in a sub-barometric pressure mode is preferred for
these reasons, a system operating in a positive pressure mode that meets the requirements of 7.2 to 7.7 is
acceptable.
7.2 Test stand performance
The test stand shall be validated as part of the overall test system (stand and associated equipment) as given
in Clause 11. Validation shall be performed whenever test conditions (e.g. flow rate) or test stand
configuration (e.g. mixing or fixture) are altered significantly. Test instruments shall be calibrated in
accordance with the manufacturer’s recommended practice and frequency.
7.3 Air supply
The influent air shall be conditioned and cleaned in accordance with 5.1 and 5.2. The system shall
demonstrate the abil
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