oSIST prEN ISO 10121-1:2025

SLOVENSKI STANDARD
01-oktober-2025
Preskusne metode za ocenjevanje lastnosti sredstev in naprav za čiščenje zraka v
plinski fazi za splošno prezračevanje - 1. del: Sredstva za čiščenje zraka v plinski
fazi (ISO/DIS 10121-1:2025)
Test method for assessing the performance of gas-phase air cleaning media and devices
for general ventilation - Part 1: Gas-phase air cleaning media (ISO/DIS 10121-1:2025)
Methode zur Leistungsermittlung von Medien und Vorrichtungen zur Reinigung der
Gasphase für die allgemeine Lüftung - Teil 1: Medien zur Reinigung der Gasphase
(ISO/DIS 10121-1:2025)
Méthodes d'essai pour l'évaluation de la performance des médias et des dispositifs de
filtration moléculaire pour la ventilation générale - Partie 1: Médias de filtration
moléculaire (GPACM) (ISO/DIS 10121-1:2025)
Ta slovenski standard je istoveten z: prEN ISO 10121-1
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 10121-1
ISO/TC 142
Test method for assessing the
Secretariat: UNI
performance of gas-phase air
Voting begins on:
cleaning media and devices for
2025-06-11
general ventilation —
Voting terminates on:
2025-09-03
Part 1:
Gas-phase air cleaning media
Méthodes d'essai pour l'évaluation de la performance des médias
et des dispositifs de filtration moléculaire pour la ventilation
générale —
Partie 1: Médias de filtration moléculaire (GPACM)
ICS: 91.140.30
THIS DOCUMENT IS A DRAFT CIRCULATED
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Reference number
ISO/DIS 10121-1:2025(en)
DRAFT
ISO/DIS 10121-1:2025(en)
International
Standard
ISO/DIS 10121-1
ISO/TC 142
Test method for assessing the
Secretariat: UNI
performance of gas-phase air
Voting begins on:
cleaning media and devices for
general ventilation —
Voting terminates on:
Part 1:
Gas-phase air cleaning media
Méthodes d'essai pour l'évaluation de la performance des médias
et des dispositifs de filtration moléculaire pour la ventilation
générale —
Partie 1: Médias de filtration moléculaire (GPACM)
ICS: 91.140.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
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Published in Switzerland Reference number
ISO/DIS 10121-1:2025(en)
ii
ISO/DIS 10121-1:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 8
4.1 Symbols .8
4.2 Abbreviated terms .9
5 Testing of different GPACM configurations . 10
5.1 General .10
5.2 Test setup and normative GPACM sample holder .10
5.3 Raw data, sampling accuracy and normative generation parameters . 12
5.4 Test parameters for the standardized benchmark test . 13
5.4.1 General . 13
5.4.2 Challenge test concentration . 13
5.4.3 GPACMs for VOC tested with toluene . 13
5.4.4 GPACMs for acids and bases tested with SO and NH respectively . 13
2 3
5.4.5 Retentivity test . 13
5.5 Test parameters selected between user and supplier .14
5.5.1 General .14
5.5.2 Face velocity and material thickness .14
5.5.3 Challenge compound . .14
5.5.4 Challenge concentration .14
5.5.5 Temperature and relative humidity .14
5.5.6 Test duration .14
6 Test sequence .15
6.1 General . 15
6.2 Conditioning and pressure drop determination . 15
6.2.1 Procedure . 15
6.2.2 Calculations . .16
6.2.3 Reporting and graphs .16
6.3 Capacity determination .16
6.3.1 Procedure (continued from 6.2.1) . .16
6.3.2 Calculations . .16
6.3.3 Reporting and graphs .19
6.4 Retentivity determination .19
6.4.1 General .19
6.4.2 Procedure (continued from 6.3.1) .19
6.4.3 Calculations . . 20
6.4.4 Reporting and graphs . 20
7 Validation of test setup.20
7.1 General . 20
7.2 Determination of rise time and decay time . 20
7.2.1 Procedure . 20
7.2.2 Calculations . .21
7.2.3 Reporting and graphs .21
8 Evaluation and report .22
8.1 Test report introduction . 22
8.2 Test report example . 22
9 Safety features . .26

iii
ISO/DIS 10121-1:2025(en)
Annex A (normative) Test equipment requirements, equipment validation and routine
operation .27
Annex B (informative) Challenge compounds, generation sources and analysis techniques .30
Annex C (informative) Design of a media test stand .36
Annex D (normative) Normative sampling procedures and test parameters for different GPACM .37
Bibliography .42

iv
ISO/DIS 10121-1:2025(en)
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
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC, Cleaning equipment for air and other gases.
This second edition cancels and replaces the first edition (ISO 10121-1:2014), which has been technically
revised.
The main changes are as follows:
— terms and definitions have been updated to conform with ISO 29464:2024;
— test compounds have been reviewed in Annex B. Challenge concentration recommendations have been
removed for compounds requiring special attention, ozone concentration have been lowered and all
other challenge concentrations conform with ISO 10121-2 and ISO 10121-3;
— clauses 6.2.1, 6.3.1, 6.4.1, 6.3.3, 6.4.2, 7.2.1 have been reworded and clarified. In addition, challenge gas,
species or compound have been changed to compound unless a specific gas e.g SO is discussed.
A list of all parts in the ISO 10121 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO/DIS 10121-1:2025(en)
Introduction
There is an increasing use and need for gas-phase filtration in general filtration applications. This demand
can be expected to increase rapidly due to the increasing pollution problems in the world together with an
increasing awareness that solutions to the problems are available in the form of filtration devices or phrased
more technically: gas-phase air cleaning devices (GPACD). The performance of devices using adsorption for
gas removal relies to a large extent on the performance of a solid gas-phase air cleaning media (GPACM)
incorporated in the device. Still applications, device performance and media performance are often poorly
understood by the user and supplier of such media and devices. Media tests may also be adequate to offer
data for real applications if actual low concentrations (<100 ppb) and longer exposure times (>weeks) can
be used in the test, provided that the geometrical configuration, packing density and flow conditions of
the small-scale test specimen are equal to those used in the real applications. Such tests are however not
included in the scope of this part of ISO 10121. This part of ISO 10121 attempts to increase understanding
and communication by supplying a more standardized interface between media suppliers, device suppliers
[1]
and end users. At present, standards exist for general ventilation in Japan by JIS, Automotive filters by ISO,
[2] [3]
in-duct sorptive media gas-phase air-cleaning devices by ASHRAE and for adsorptive media by ASHRAE
[5]
and ASTM . No international standard for general filtration exists today.
This part of ISO 10121 provides methods, test equipment, data interpretation and reporting for three
different types of gas-phase air cleaning media (GPACM) intended for use in gas-phase air cleaning devices
(GPACD) for general ventilation applications.
In addition information is given in a number of annexes:
— Annex A describes the normative validation procedure in detail in a tabulated form.
— Annex B gives a list of possible test compounds, generation sources and suggests proper analysis
equipment for common test compounds
— Annex C describes the design of the test stand except the normative sample holder.
— Annex D describes the normative test setup and normative section of the test stand for the three different
media configurations.
A general introduction to molecular filtration and molecular filtration testing can be found in the scientific
literature.
The ISO 10121 series consists of three parts.
— ISO 10121-1 covers three different media configurations and aims to provide a standardized interface
between media suppliers and producers of air cleaning devices. It may also be used between media
suppliers and end customers with regards to loose fill media properties.
— ISO 10121-2 aims to provide a standardized interface between suppliers of air cleaning devices and end
customers seeking the most cost-efficient way to employ gas-phase filtration.
— ISO 10121-3 provides a classification system for the specific application of GPACDs in general, ventilation
systems for cleaning of outdoor air polluted by local urban sources and/or long-range transboundary air
pollution.
vi
DRAFT International Standard ISO/DIS 10121-1:2025(en)
Test method for assessing the performance of gas-phase air
cleaning media and devices for general ventilation —
Part 1:
Gas-phase air cleaning media
1 Scope
This document aims to provide an objective laboratory test method, a suggested apparatus, normative test
sections and normative tests for evaluation of three different solid gas-phase air cleaning media (GPACM) or
GPACM configurations for use in gas-phase air cleaning devices intended for general filtration applications.
This document is specifically intended for challenge testing and not for general material evaluation or pore
system characterization. The three different types of GPACM identified in this document are:
— GPACM-LF (particles of different shape and size intended for e.g. Loose Fill applications),
— GPACM-FL (FLat sheet fabric intended for e.g. flat one layer, pleated or bag type devices) and,
— GPACM-TS (three dimensional structures that are many times thicker than flat sheet and e.g. used as
finished elements in a device).
The tests are conducted in an air stream and the GPACM configurations are challenged with test compounds
under steady-state conditions. Since elevated challenge concentrations (relative to general ventilation
applications) are used, test data should be used to compare GPACM within the same configuration and not
for the purpose of predicting performance in a real situation. It is also not implied that different GPACM
configurations can be directly compared. The primary intention is to be able to compare like GPACM
configurations to like, not between GPACM configurations. Testing of complete devices is described in
ISO 10121-2.
To ensure objectivity for test equipment suppliers, no specific design of the test apparatus is defined: an
example is illustrated in Annex C (informative). Instead normative demands for media sample holder design,
apparatus properties and validation tests are specified.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 10121-2, Test methods for assessing the performance of gas-phase air cleaning media and devices for general
ventilation — Part 2: Gas-phase air cleaning devices (GPACD)
ISO 29464:2024, Cleaning of air and other gases — Vocabulary
ASTM D 2854-9: 2019, Standard Test Method for Apparent Density of Activated Carbon
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 29464 and the following apply.

ISO/DIS 10121-1:2025(en)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
absorption
transport and dissolution of one substance into another to form a mixture having the characteristics of a
solution
[SOURCE: ISO 29464:2024; 3.5.1]
3.2
adsorbate
molecular compound in gaseous or vapour phase that can be retained by the adsorbent medium
[SOURCE: ISO 29464:2024; 3.5.3]
3.3
adsorbent
solid material having the ability to retain gases or vapour on its surface through physical or chemical
processes
[SOURCE: ISO 29464:2024; 3.5.4]
3.4
adsorbent isotherm
relationship between the amount of a gas physically adsorbed on a surface and the partial pressure of the
gas at constant temperature.
3.5
adsorption
process in which the molecules of a gas or vapour adhere by physical or chemical processes to the exposed
surface of solid substances, both the outer surface and inner pore surface, with which they come into contact
[SOURCE: ISO 29464:2024; 3.5.7]
3.6
breakthrough
amount of gaseous contaminant in the effluent of a GPACM sample.
Note 1 to entry: See penetration (3.35).
3.7
breakthrough vs. time curve
plot of contaminant penetration versus time for a particular challenge concentration and air flow
[SOURCE: ISO 29464:2024; 3.5.12]
3.8
bypass
proportion of the challenge air stream that passes around or through an air cleaner without interacting with
the air cleaner
[SOURCE: ISO 29464:2024; 3.1.5]

ISO/DIS 10121-1:2025(en)
3.9
capacity
m
s
amount (mass or moles) of a selected sorbate that can be contained in the GPAC Media or Device at given test
conditions, and a specific end point
Note 1 to entry: Capacity can also be negative during desorption.
3.10
challenge concentration
concentration of the test contaminant(s) of interest in the air stream prior to filtration (challenge air stream)
[SOURCE: ISO 29464:2024; 3.5.16]
3.11
challenge compound
chemical compound that is being used as the contaminant of interest for any given test
[SOURCE: ISO 29464:2024; 3.5.15]
3.12
challenge air stream
test contaminant(s) of interest diluted to the specified concentration(s) of the test prior to filtration
[SOURCE: ISO 29464:2024; 3.5.14]
3.13
channelling
disproportionate or uneven flow of gas through passages of lower resistance due to inconsistencies in the
design or production of a GPACD, particularly in packed granular beds
[SOURCE: ISO 29464:2024; 3.5.17]
3.14
chemisorption
chemical adsorption
trapping of gaseous or vapour contaminants on an adsorbent involving chemical reaction on the
adsorbent surface
[SOURCE: ISO 29464:2024; 3.5.19]
3.15
concentration
C
n
quantity of one substance dispersed in a defined amount of another
Note 1 to entry: Indices “n” denote location or origin.
[SOURCE: ISO 29464:2024; 3.1.11]
3.16
contaminant
substance (solid, liquid, or gas) that negatively affects the intended use of a gas
[SOURCE: ISO 29464:2024; 3.1.12]

ISO/DIS 10121-1:2025(en)
3.17
decay time
t
Dn
time required for the gas contaminant monitoring instrument to record a reduction from an initial
value greater than 95 % of the challenge concentration to a final value of less than 5 % of the challenge
concentration (t - t ) at the downstream sampling point for a specific test (n), challenge gas and gas flow
END VC
after stopping the injection of the contaminant with no GPAC media or device present
[SOURCE: ISO 29464:2024; 3.5.21]
3.18
desorption
process in which adsorbate molecules leave the surface of the adsorbent and re-enter the air stream
Note 1 to entry: Desorption is the opposite of adsorption.
[SOURCE: ISO 29464:2024; 3.5.22]
3.19
diffusor
device that forces the air stream to achieve an even face velocity over the entire cross sectional area of a test duct.
Note 1 to entry: The device may be a perforated plate.
3.20
downstream
area or region into which air flows on leaving an air cleaner
[SOURCE: ISO 29464:2024; 3.1.16]
3.21
removal efficiency vs. time curve
plot of the GPAC medium or device removal efficiency against time over the duration of a challenge test for a
particular challenge concentration and air flow
[SOURCE: ISO 29464:2024; 3.5.58]
3.22
removal efficiency vs. capacity curve
plot of the GPACD removal efficiency against the integrated capacity over the duration of a challenge test for
a particular challenge concentration and air flow
[SOURCE: ISO 29464:2024; 3.5.56]
3.23
face velocity
volumetric air flow rate divided by nominal air cleaner face area
[SOURCE: ISO 29464:2024; 3.1.20]
3.24
gas
substance whose vapour pressure is greater than the ambient pressure at ambient temperature
[SOURCE: ISO 29464:2024; 3.1.34]
3.25
gas-phase air cleaning device
GPACD
assembly of a fixed size enabling the removal of specific gas- or vapour-phase contaminants
Note 1 to entry: It is normally box shaped or fits into a box of dimensions between 300 mm × 300 mm × 300 mm up to
approximately 610 mm × 610 mm × 610 mm or 2 feet × 2 feet × 2 feet.

ISO/DIS 10121-1:2025(en)
[SOURCE: ISO 29464:2024; 3.5.34, modified – Note 1 to entry has been modified.]
3.26
GPAC media or device face area
cross-sectional area of the GPAC Media or Device also including a header frame or other support structures
if so equipped when viewed from the direction of air flow using exact dimensions
[SOURCE: ISO 29464:2024; 3.5.36]
3.27
gas-phase air cleaning medium
GPACM
solid media or media configuration used for filtering a contaminant
EXAMPLE A porous film or fibrous layer; a bead shaped, granular or pelletized adsorbent (or chemisorbent); a
support structure of fabric, foam or monoliths containing adsorbent in the form of small sized particles, granules,
spheres or powder; a woven or nonwoven fabric completely made from an adsorbent material.
[SOURCE: ISO 29464:2024; 3.5.37]
3.28
GPACM-LF
adsorbent in the form of particles of different shape and size intended for loose fill applications for example
[SOURCE: ISO 29464:2024; 3.5.39]
3.29
GPACM-FL
adsorbent in the form of flat sheet that is flexible, thin, and nominally two-dimensional
EXAMPLE Woven or nonwoven fabrics, wet laid papers, smooth pads, felts etc. normally handled as roll goods.
[SOURCE: ISO 29464:2024; 3.5.38]
3.30
GPACM-TS
adsorbent in the form of a three-dimensional structure that is many times thicker than flat sheet and used
as a finished element in a device
EXAMPLE Flexible open cell structures, i.e. of thicker impregnated foam, corrugated pads etc. and air permeable
rigid structures, i.e. of bonded particles, honeycomb trays, extruded monoliths, etc.
[SOURCE: ISO 29464:2024; 3.5.40]
3.31
initial efficiency
E
i
efficiency calculated as the intersection of vertical efficiency axis by extrapolation of a linear fit of efficiency
vs. time from the values between 2 to 12 minutes of the E vs. time graph generated during testing of a GPAC
Media or Device
3.32
molecular contamination
contamination present in gas or vapour phase in an air stream and excluding compounds in particulate
(solid) phase regardless of their chemical nature
[SOURCE: ISO 29464:2024; 3.5.43]

ISO/DIS 10121-1:2025(en)
3.33
ppb(v)
parts per billion by volume concentration measure normally used to record ambient levels of outdoor
pollution
3 3
Note 1 to entry: Units are mm /m .
[SOURCE: ISO 29464:2024; 3.5.46]
3.34
ppm(v)
parts per million by volume concentration measure normally used to record pollution levels in, for example
work place safety
3 3 3
Note 1 to entry: Units are cm /m and ml/m .
[SOURCE: ISO 29464:2024; 3.5.47]
3.35
penetration
P
ratio of contaminant concentration downstream of an air cleaner to the upstream (challenge) concentration
Note 1 to entry: Sometimes expressed as a percentage.
Note 2 to entry: Penetration (P) related to removal efficiency (E) by the expression: E = (1 – P) × 100 %.
Note 3 to entry: Penetration is related to the decontamination factor (DF) by the expression: DF = 1/penetration
[SOURCE: ISO 29464:2024; 3.1.41]
3.36
physisorption
physical adsorption
attraction of an adsorbate to the surface, both outer surface and inner pore surface, of an adsorbent by
physical forces (Van der Waals forces)
[SOURCE: ISO 29464:2024; 3.5.48]
3.37
pores
minute passageways through which gas can pass or that expose to the gas stream the internal surfaces of an
adsorbent medium
[SOURCE: ISO 29464:2024; 3.5.49]
3.38
pressure drop
Δp
difference in pressure between two points in an air flow system at specified conditions, especially when
measured across a GPAC Media or Device
3.39
removal efficiency
E
fraction or percentage of a challenge contaminant that is removed by an air cleaner
[SOURCE: ISO 29464:2024; 3.1.17]

ISO/DIS 10121-1:2025(en)
3.40
retentivity
m
r
measure of the ability of an adsorbent or GPACD to resist desorption of an adsorbate
Note 1 to entry: Computed as the residual capacity (fraction remaining) after purging the adsorbent with clean,
conditioned air only, following challenge breakthrough.
[SOURCE: ISO 29464:2024; 3.5.63]
3.41
residence time
t
r
relative time that an increment of gas (or contaminant) is within the boundaries of the medium volume
Note 1 to entry: An example of the medium volume is a bed of granules or a non-woven sheet.
Note 2 to entry: In typical use and in this document, this value neglects the fact that the medium and possible support
structures occupy a significant portion of the volume of the bed (residence time is calculated as total bed volume/ air
flow rate). .
[SOURCE: ISO 29464:2024; 3.5.62]
3.42
rise time
t
Rn
time between initial injection of contaminant and reaching 95 % of the challenge concentration for an empty
duct (t - t ) measured at the downstream sampling
0 VO
Note 1 to entry: rise time is specific to a particular test, challenge gas and gas flow rate
[SOURCE: ISO 29464:2024; 3.5.42]
3.43
sorbate
molecular compounds that are retained in the adsorbent of the device
Note 1 to entry: The sorbate will refer to both intended compounds like the selected challenge gas in a test or pollution
in real service but also any other compounds present in the air stream, e.g. gases and vapours.
[SOURCE: ISO 29464:2024; 3.5.66]
3.44
sorption
process in which gas or liquid molecules are removed by the GPACM by absorption or adsorption
[SOURCE: ISO 29464:2024; 3.5.67]
3.45
space velocity
sv
measure of residence time of the air flow to pass through the adsorbent bed
EXAMPLE Space velocity = volumetric flow rate/total volume of the bed.
−1
Note 1 to entry: Space velocity= (residence time) .
[SOURCE: ISO 29464:2024; 3.5.68]

ISO/DIS 10121-1:2025(en)
3.46
vapour
substance whose vapour pressure is less than the ambient pressure at ambient temperature, but is present
in the gas phase through evaporation or sublimation
[SOURCE: ISO 29464:2024; 3.5.72]
4 Symbols and abbreviated terms
4.1 Symbols
C concentration
C downstream concentration [ppb, ppm] measured at a position Y mm after the media sample or
D
device
C upstream concentration [ppb, ppm] measured at a position X mm before the media sample or device
U
d the average particle diameter of a loose fill adsorbent
pa
E removal efficiency [%] for the device measured at the challenge concentration selected during
C
the capacity test
E efficiency recorded at stop test time or value agreed between user and supplier [%]
END
m retentivity; [g],[mol] the amount withheld by the media or device after ventilating with clean air
r
at the same flow selected during the capacity test until C reaches a specified value close to zero.
D
m the total integrated amount [g], [mol] of challenge compound accumulated by the GPAC media or
s
device during the whole challenge test
m the integrated amount in moles or gram of challenge compound accumulated during measurement
sD
at the downstream position
m the integrated amount in moles or gram of challenge compound accumulated during measurement
sU
at the upstream position
n the number of pores along the (shortest) diameter of a GPACM-TS sample
p
p downstream pressure [Pa] measured at a position Y mm after the media sample or device
D
p upstream pressure [Pa] measured at a position X mm before the media sample or device
U
Q air flow rate; flow used in test (given by 5.4 or 5.5) [m /h] measured at a position Z mm from the
media sample or device
Q the average air flow rate calculated from individual measurements evenly distributed over the
A
test period.
RH downstream relative humidity [%] measured at a position Y mm after the media sample or device
D
RH upstream relative humidity [%] measured at a position X mm before the media sample or device
U
t time
t start time. The time when C (contamination concentration upstream) equals the selected chal-
0 U
lenge concentration for an empty sample holder or duct
t decay time for challenge concentration used in the capacity measurement
DC
ISO/DIS 10121-1:2025(en)
t time when a test is stopped. The time when a desired concentration or other termination criteria
END
have been met in any of the prescribed test procedures (agreed between user and supplier)
t rise time for challenge concentration used in the capacity measurement
RC
t time noted at challenge gas valve closure
VC
t time noted at challenge gas valve opening
VO
T downstream temperature [°C] measured at a position Y mm after the media sample or device
D
T upstream temperature [°C] measured at a position X mm before the media sample or device
U
v face velocity [m/s] calculated from flow and cross sectional area of media sample or device
f
X a position X positioned sufficiently far ahead of the device to allow undisturbed measurements,
determined in the validation, Annex A. At the position X the concentration of challenge compound
is sufficiently mixed and represents the upstream concentration that the GPACM sample will be
challenged with.
x the minimum recommended distance from the highest part of the sample holder with the same
diameter as the upstream side of the sample
Y a position Y positioned sufficiently far after the device to allow undisturbed measurements, de-
termined in the validation section, Annex A. At the position Y the concentration of penetrating
challenge compound is sufficiently mixed and represents the average downstream concentration
after the GPACM sample.
y the minimum recommended distance from the downstream side of the sample to the lowest part
of the sample holder with the same diameter as the sample.
Z a position Z positioned sufficiently far from the media or device to permit a reliable flow meas-
urement using an orifice device, determined in the validation, Annex A.
Δp pressure drop measured over the tested media sample or device [Pa]
4.2 Abbreviated terms
ASHRAE American Society of Heating Refrigerating and Air-conditioning Engineers
ASTM ASTM International, formerly known as the American Society for Testing and Materials (ASTM)
HEPA High Efficiency Particulate Air (filter)
JIS Japanese Industrial Standards
JSA Japanese Standards Association
MSDS Material Safety Data Sheet
NMP n-Methyl −2-pyrrolidone
TLV threshold limit value. Amount of a chemical substance is a level to which it is believed a worker
can be exposed day after day for a working lifetime without adverse health effects.
VOC Volatile Organic Compound
ISO/DIS 10121-1:2025(en)
5 Testing of different GPACM configurations
5.1 General
This document shows how to measure four key parameters that reflect the performance of a GPACM. The
four parameters are:
— pressure drop, Δp;
— capacity, m ;
s
— removal efficiency, E;
— retentivity, m .
r
These parameters are:
— linked to each other;
— different for different challenge compounds (exception; Δp is not affected);
— different for different concentrations of the same challenge compound (exception; Δp is not affected);
— affected by other gases present, by temperature, by humidity and by the air flow;
— different for different particle sizes of loose fill samples occupying the same volume;
— different for identical materials subjected to different face velocities and/or material thicknesses.
In order to perform tests at sufficiently short test times the concentration is strongly increased to accelerate
the test. In this document two concentration levels are suggested for the determination of capacity in 5.4.
Clause 5 describes the normative part of the test stand and normative sample holder for different GPACM,
normative parameters for generation of the challenge air stream and test compounds for benchmark
purposes. Clause 6 describes in detail the test sequence for conditioning and for determination of pressure
drop, removal efficiency, capacity and retentivity in this order.
5.2 Test setup and normative GPACM sample holder
The GPACM sample holder shall be installed without leakages or bypass. The air stream should be uniformly
mixed and with equal velocity and upstream concentration over the cross section. A schematic view of the
sample holder is shown in Figure 1. Recorded parameters are concentration C, pressure p, temperature T
and relative humidity RH in two positions. The air flow is recorded at a third position that may be upstream
or downstream of the sample holder. The sample holders should be vertical and the flow direction is most
logically from top to bottom as indicated in Figure 1. In this way bed disturbances due to the flow are
avoided. However, if spring loaded screens are used to hold the material the flow direction may be from
bottom to top as well. This document exemplifies the procedure of measuring a single sample. A test stand
with multiple parallel sample holders is often used and may be advantageous. The procedure can easily be
expanded to work with multiple measurements as discussed in 6.1.

ISO/DIS 10121-1:2025(en)
Key
1 example of air flow measurement device location at point Z
2 upstream sampling point for T , RH , p and C at point X
U U U U
3 diffusor at a distance x from the media sample surface
4 GPAC media sample of diameter D and thickness T, see Annex D
5 diffusor at a distance y from the media sample surface
6 downstream sampling point for T , RH , p and C at point Y
D D D D
Figure 1 — Schematic view of a sample holder sho
...