EN ISO 29462:2022

SLOVENSKI STANDARD
01-oktober-2022
Nadomešča:
SIST EN ISO 29462:2013
Terensko preskušanje splošnih prezračevalnih filtrirnih naprav in sistemov na
kraju samem (kraju vgradnje) glede učinkovitosti odstranjevanja delcev po njihovi
velikosti in glede upornosti proti zračnemu toku (ISO 29462:2022)
Field testing of general ventilation filtration devices and systems for in situ removal
efficiency by particle size and resistance to airflow (ISO 29462:2022)
Betriebserprobung von Filtereinrichtungen und -systemen für die allgemeine Lüftung
hinsichtlich ihrer Abscheideeffizienz im eingebauten Zustand bezogen auf die
Partikelgröße und den Druckverlust (ISO 29462:2022)
Essais in situ de filtres et systèmes de ventilation générale pour la mesure de l'efficacité
en fonction de la taille des particules et de la résistance à l'écoulement de l'air (ISO
29462:2022)
Ta slovenski standard je istoveten z: EN ISO 29462:2022
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
23.120 Zračniki. Vetrniki. Klimatske Ventilators. Fans. Air-
naprave conditioners
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.

EN ISO 29462
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2022
EUROPÄISCHE NORM
ICS 91.140.30 Supersedes EN ISO 29462:2013
English Version
Field testing of general ventilation filtration devices and
systems for in situ removal efficiency by particle size and
resistance to airflow (ISO 29462:2022)
Essais in situ de filtres et systèmes de ventilation Betriebserprobung von Filtereinrichtungen und -
générale pour la mesure de l'efficacité en fonction de la systemen für die allgemeine Lüftung hinsichtlich ihrer
taille des particules et de la résistance à l'écoulement Abscheideeffizienz im eingebauten Zustand bezogen
de l'air (ISO 29462:2022) auf die Partikelgröße und den Druckverlust (ISO
29462:2022)
This European Standard was approved by CEN on 22 July 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 29462:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 29462:2022) has been prepared by Technical Committee ISO/TC 142 "Cleaning
equipment for air and other gases" in collaboration with Technical Committee CEN/TC 195 “Cleaning
equipment for air and other gases” the secretariat of which is held by UNI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2023, and conflicting national standards
shall be withdrawn at the latest by February 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 29462:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 29462:2022 has been approved by CEN as EN ISO 29462:2022 without any modification.

INTERNATIONAL ISO
STANDARD 29462
Second edition
2022-07
Field testing of general ventilation
filtration devices and systems for in
situ removal efficiency by particle size
and resistance to airflow
Essais in situ de filtres et systèmes de ventilation générale pour la
mesure de l'efficacité en fonction de la taille des particules et de la
résistance à l'écoulement de l'air
Reference number
ISO 29462:2022(E)
ISO 29462:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 29462:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 3
4 Test equipment and setup . 4
4.1 Particle counter . 4
4.2 Diluter . 4
4.3 Pump . . 4
4.4 Sampling system . 4
4.4.1 General . 4
4.4.2 Sampling probes . 5
4.4.3 Sampling lines . 5
4.4.4 Sampling locations . 5
4.4.5 Valve (manual or automatic) . 6
4.4.6 Isoaxial sampling nozzle . 6
4.4.7 Flow meter . 7
4.5 Air velocity measurement instrument . 7
4.6 Relative humidity (RH) measurement instrument . 7
4.7 Temperature measurement instrument . 7
4.8 Resistance to airflow measurement instrument . 7
4.9 Test equipment maintenance and calibration . 7
5 Site evaluation . 8
5.1 General . 8
5.2 Filter installation pre-testing inspection . 8
5.3 Approval for testing . 8
6 Test procedure .8
6.1 Air velocity . 8
6.2 Relative humidity (RH) . 9
6.3 Temperature . 9
6.4 Resistance to airflow . 9
6.5 Removal efficiency . 10
6.5.1 Removal efficiency tests . 10
6.5.2 Sampling method . 10
6.6 Sampling probes . 14
6.6.1 Location of sampling probes . 14
6.6.2 Location of upstream sampling probes . 14
6.6.3 Location of downstream sampling probes — Filter efficiency test. 14
6.6.4 Location of downstream sampling probes — System efficiency test . 14
7 Expression of results .14
7.1 General information. 14
7.2 Data collection . 16
8 Errors and data analyses .17
8.1 General . 17
8.2 Relative humidity (RH) . 17
8.3 Air temperature . 17
8.4 Aerosol composition . 17
8.5 Uniformity of aerosol concentration . 17
8.6 Coincidence errors — Particle counter . 18
iii
ISO 29462:2022(E)
8.7 Particle losses . 18
9 Calculation of results .18
9.1 Calculation of removal efficiency . 18
9.1.1 General . 18
9.1.2 Dataset sample average . . 18
9.1.3 Minimum upstream concentration . 19
9.1.4 Particle size range efficiency. 20
9.1.5 Average efficiency by particle size . 20
9.2 Calculation of uncertainty .20
9.2.1 General .20
9.2.2 95 % confidence limit. 20
9.3 Coefficient of variation (C ) . 21
v
10 Optional enhanced test system .22
10.1 Application of enhanced test system . 22
10.2 Principle of the enhanced test system . 22
10.3 Determination of the corrected particle size . 23
10.4 Presentation of results . 24
Annex A (informative) Filter installation pre-testing inspection form .25
Annex B (informative) Approval for testing form .27
Annex C (informative) Example of how to complete testing .28
Bibliography .42
iv
ISO 29462:2022(E)
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.
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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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 142, Cleaning equipment for air and other
gases, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 195, Cleaning equipment for air and other gases, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 29462:2013), which has been technically
revised.
The main changes are as follows:
— subclause 4.2 has been modified;
— some editorial corrections have been made.
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 29462:2022(E)
Introduction
The purpose of this document is to provide a test procedure for evaluating the in situ performances
of general ventilation filtration devices and systems. Although any filter with a filtration efficiency at
or above 99 % or at or below 30 % when measured at 0,4 μm can theoretically be tested using this
document, it can be difficult to achieve statically acceptable results for these type of filtration devices.
Supply air to the heating, ventilation and air-conditioning (HVAC) system contains viable and non-viable
particles of a broad size range. Over time these particles cause problems for fans, heat exchangers and
other system parts, decreasing their function and increasing energy consumption and maintenance.
For health issues, the fine particles (< 2,5 µm) are the most detrimental.
Particles in the 0,3 μm to 5,0 μm size range are typically measured by particle counters that can
determine the concentration of particles in specific size ranges. These instruments are commercially
available and determine particle size along with the concentration level by several techniques (e.g. light
scattering, electrical mobility separation, or aerodynamic drag). Devices based on light scattering are
currently the most convenient and commonly used instruments for this type of measurement and are
therefore the type of device used within this document.
Particles in the size range 1,0 μm to 5,0 μm are present in low numbers (less than 1 %, by count) in
outdoor and supply air and have higher sampling-system losses. Results in the range > 1,0 μm therefore
have lower accuracy and should be interpreted accordingly.
During in situ measurement conditions, the optical properties of the particles can differ from the optical
properties of the particles used for calibrating the particle counter and testing it in the laboratory. Thus
the particle counter can size the particles differently but count the overall number of particles correctly.
By adding an extra reference filter, the effect of varying measuring conditions can be reduced.
Additionally, using this enhanced test method, the results can be used to correct the measured
efficiencies in relation to the efficiency of the reference filter measured in laboratory using a
standardized test aerosol.
The results from using the standard method or the enhanced method give both users and manufacturers
a better knowledge of actual filter and installation properties.
It is important to note that field measurements generally result in larger uncertainties in the results
compared to laboratory measurements. Field measurements can produce uncertainty from temporal
and spatial variability in particle concentrations, from limitations on sampling locations due to air
handling unit configurations, and from the use of field instrumentation. These factors can result
in lower accuracy and precision in the calculated fractional efficiencies compared to laboratory
measurements. This document is intended to provide a practical method in which the accuracy and
precision of the result are maximized (and the precision of the result quantified) by recommending
appropriate sampling locations, sample quantities, and instrumentation. This document is not intended
to serve as a filter performance rating method. The results obtained from the test method described in
this document do not replace those obtained through tests conducted in the laboratory.
vi
INTERNATIONAL STANDARD ISO 29462:2022(E)
Field testing of general ventilation filtration devices and
systems for in situ removal efficiency by particle size and
resistance to airflow
1 Scope
This document describes a procedure for measuring the performance of general ventilation air cleaning
devices in their end use installed configuration. The performance measurements include removal
efficiency by particle size and the resistance to airflow. The test procedures include the definition and
reporting of the system airflow.
The procedure describes a method of counting ambient air particles of 0,3 μm to 5,0 μm upstream and
downstream of the in-place air cleaner(s) in a functioning air handling system. The procedure describes
the reduction of particle counter data to calculate removal efficiency by particle size.
Since filter installations vary dramatically in design and shape, a protocol for evaluating the suitability
of a site for filter evaluation and for system evaluation is included. When the evaluated site conditions
meet the minimum criteria established for system evaluation, the performance evaluation of the system
can also be performed according to this procedure.
This document also describes performance specifications for the testing equipment and defines
procedures for calculating and reporting the results. This document is not intended for measuring
performance of portable or movable room air cleaners or for evaluation of filter installations with an
expected filtration efficiency at or above 99 % or at or below 30 % when measured at 0,4 μm.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1.1
air filter bypass
proportion of the challenge air stream that passes around an air cleaner without interacting with the
air cleaner (test device)
[SOURCE: ISO 29464:2017; 3.1.3, modified — The preferred terms "bypass" and "sneakage" have been
deleted and "(test device)" has been added.]
3.1.2
air velocity
rate of air movement at the test device
Note 1 to entry: It is expressed in m/s (ft/min) to three significant figures.
ISO 29462:2022(E)
[SOURCE: ISO 29464:2017, 3.1.2, modified — “at the test device” has been added to clarify the location,
"fpm" has been changed to "ft/min".]
3.1.3
allowable measurable concentration of the particle counter
fifty percent of the maximum measurable concentration as stated by the manufacturer of the particle
counter (3.1.12)
[SOURCE: ISO 29464:2017, 3.2.115]
3.1.4
coefficient of variation
C
V
standard deviation of a group of measurements divided by the mean
[SOURCE: ISO 29464:2017, 3.2.31]
3.1.5
coincidence error
error which occurs because at a given time more than one particle is contained in the measurement
volume of a particle counter (3.1.12)
Note 1 to entry: The coincidence error leads to a measured number concentration which is too low and a value for
the particle diameter which is too high.
[SOURCE: ISO 29464:2017, 3.2.32]
3.1.6
diluter
dilution system
system for reducing the sampled concentration to avoid coincidence error (3.1.5) in the particle counter
(3.1.12)
[SOURCE: ISO 29464:2017, 3.2.46]
3.1.7
filter efficiency
fraction or percentage of a challenge contaminant that is removed by a test device
[SOURCE: ISO 29464:2017, 3.1.12, modified — The preferred term "efficiency" has been deleted.]
3.1.8
filter installation
filtration devices and systems such as a single filter or a group of filters mounted together with the
same inlet and outlet of air
[SOURCE: ISO 29464:2017, 3.2.85]
3.1.9
general ventilation
process of moving air from outside the space, recirculated air, or a combination of these into or about a
space or removing it from the space
[SOURCE: ISO 29464:2017, 3.2.100]
3.1.10
isoaxial sampling
sampling in which the flow in the sampler inlet is moving in the same direction as the flow being
sampled
[SOURCE: ISO 29464:2017, 3.2.104]
ISO 29462:2022(E)
3.1.11
isokinetic sampling
technique for air sampling such that the probe inlet air velocity (3.1.2) is the same as the velocity of the
air surrounding the sampling point
[SOURCE: ISO 29464:2017, 3.2.105]
3.1.12
particle counter
device for detecting and counting numbers of discrete airborne particles present in a sample of air
[SOURCE: ISO 29464:2017, 3.2.114]
3.1.13
particle size range
defined particle counter (3.1.12) channel
[SOURCE: ISO 29464:2017, 3.2.137]
3.1.14
reference filter
dry media-type filter that has been laboratory tested for removal efficiency by particle size (3.1.15)
3.1.15
removal efficiency by particle size
removal efficiency
ratio of the number of particles retained by the filter to the number of particles measured upstream of
the filter for a given particle-size range
[SOURCE: ISO 29464:2017, 3.2.149, modified — The preferred term "removal efficiency" has been
added.]
3.1.16
resistance to airflow
difference in absolute (static) pressure between two points in a system
Note 1 to entry: Resistance to airflow is measured in Pa.
[SOURCE: ISO 29464:2017, 3.1.36, modified — The preferred terms "differential pressure", "pressure
differential" and "pressure drop" have been deleted.]
3.1.17
system efficiency
removal efficiency (3.1.15) of a filter system where upstream and downstream particle count
measurements may be across several filter banks or other system components
[SOURCE: ISO 29464:2017, 3.2.163]
3.1.18
HEPA filter
filters with performance complying with requirements of filter class ISO 35H to ISO 45H as per
ISO 29463-1
[SOURCE: ISO 29464:2017, 3.2.84]
3.2 Abbreviated terms
AHU air handling unit
D/S downstream of test device
ISO 29462:2022(E)
HVAC heating, ventilating and air-conditioning
OPC optical particle counter
RH relative humidity
U/S upstream of test device
VAV variable air volume
VFD variable frequency drive
4 Test equipment and setup
4.1 Particle counter
The particle counter should be capable of measuring particles in the size range 0,3 µm to 5,0 µm, in a
minimum of four ranges with a minimum of two ranges below 1,0 μm (for example: 0,3 µm to 0,5 μm,
0,5 µm to 1,0 μm, 1,0 µm to 2,0 μm and 2,0 µm to 5,0 μm). For maintenance and calibration of the
particle counter, see 4.9.
4.2 Diluter
A dilution system is required if the upstream aerosol concentration exceeds 50 % of the particle counter
maximum concentration at 5 % coincidence error. The dilution system shall be capable of diluting the
aerosol concentration so the particle concentration level is within the acceptable concentration limit.
Choose a suitable dilution ratio so that the measured concentration of particles is within the limits of
the allowable measurable concentration of the particle counter so as to achieve good statistical data
(see 9.1.2). If a dilution system is used, it shall be used for both upstream and downstream sampling.
The dilution system shall not change air flow to the particle counter.
4.3 Pump
A pump may be used to control the rate of the sample flow (q ) through the sampling probes. A pump is
s
not necessary when the counter flow (q ) to the counter or diluter is sufficient for isokinetic sampling.
pc
In this case the sample flow (q ) and the counter flow (q ) are the same.
s pc
4.4 Sampling system
4.4.1 General
Figure 1 shows the elements of a typical sampling system.
ISO 29462:2022(E)
Key
1 test device 7 particle counter
2 U/S probe 8 pump
3 D/S probe 9 flow meter
a
4 manometer q – primary flow
s
b
5 sample valve q – flow to particle counter
pc
6 isokinetic sampler
Figure 1 — Sampling system
4.4.2 Sampling probes
The sampling probe should consist of a sharp-edged nozzle connected to the sample line leading to the
auxiliary pump or particle counter. The diameter of the nozzle is dependent on the sample flow (q ) in
s
order to get isokinetic sampling. The diameter should not be less than 8 mm.
4.4.3 Sampling lines
Sampling lines upstream and downstream should be of equal length and as short as possible to avoid
losses. Material should preferably be of a type with minimum particle losses for filter installations.
[2]
Software is available to calculate line losses .
4.4.4 Sampling locations
Sampling locations should be placed close to the filter as shown in Figure 2. If the system efficiency is
to be tested, the sampling locations should be further away to achieve good mixing of airflow through,
e.g. filters, frames, doors. The measurement of the system efficiency is more difficult and therefore it is
good practice to plan the measurement carefully and describe in detail how it was made.
ISO 29462:2022(E)
Dimension in millimetres
Key
A minimum distance between the sampling probe and the filter
B distance between the end of the filter and the sampling probe
C location of sample points in y-z plane for filter efficiency tests
1 U/S sampling probe location
2 D/S sampling probe location for a filter efficiency test
3 D/S sampling probe location for a system efficiency test
Figure 2 — Sampling locations
4.4.5 Valve (manual or automatic)
A valve may be used to switch between upstream and downstream sample locations. The valve should
be constructed so that particle losses are identical in upstream and downstream measurements. No
influence on efficiency due to the valve construction is permitted (for example, four-point ball valves of
sufficient diameter can be used).
4.4.6 Isoaxial sampling nozzle
If a pump (see 4.3) is used to obtain isokinetic sampling, the sample line should then be fitted with an
isoaxial sampling nozzle directly connected to the particle counter or diluter as shown in Figure 3.
Key
a
Pump flow.
b
q – flow to particle counter.
pc
c
q – sample flow.
s
Figure 3 — Isoaxial sampling line to particle counter
ISO 29462:2022(E)
4.4.7 Flow meter
A flow meter is necessary if a pump is part of the sampling system. The flow meter should be located
in-line with the pump inlet or outlet.
4.5 Air velocity measurement instrument
The instrument used to measure the air velocity should have sufficient operational limits such that the
system airflow is within the limits of the instrument. The instrument should be chosen in accordance
with ISO 7726. An instrument that records data values and averages those values is recommended.
Ideally, the instrument should have the ability to correct measurements to standard sea level
atmospheric pressure conditions.
4.6 Relative humidity (RH) measurement instrument
The instrument used to measure the RH of the system airflow should have sufficient operational limits
such that the system RH is within the limits of the instrument and should be chosen in accordance with
ISO 7726. An instrument that records data values and averages those values over time is recommended.
4.7 Temperature measurement instrument
The instrument used to measure the temperature of the system airflow should have sufficient
operational limits such that the system temperature is within the limits of the instrument and should
be chosen in accordance with ISO 7726. An instrument that records data values and averages those
values over time is recommended.
4.8 Resistance to airflow measurement instrument
The instrument used to measure the resistance of the filter bank should have sufficient operational
limits such that the filter bank resistance is within the limits of the instrument, and should be chosen in
accordance with ISO 14644-3. An instrument that records data values and averages those values over
time is recommended.
4.9 Test equipment maintenance and calibration
Maintenance items and schedules should conform to Table 1.
Table 1 — Apparatus maintenance schedules
After a change that
Incorporated
Maintenance item Annually can alter
into each test
performance
Particle counter zero check X
Sampling system zero check X
Resistance to airflow X
Air velocity X
Temperature, RH in sample air
X
stream and at particle counter
Upstream concentration test X
Reference filter test (field) optional
Reference filter test (lab) X X
Particle counter primary
X X
calibration
a
Or as required by the equipment manufacturer.
ISO 29462:2022(E)
Table 1 (continued)
After a change that
Incorporated
Maintenance item Annually can alter
into each test
performance
Temperature, RH, air velocity,
a
resistance to airflow equipment X X
calibration
Dilution system ratio check X X
Check sample probes for
X
damage
a
Or as required by the equipment manufacturer.
5 Site evaluation
5.1 General
This clause identifies the recommended minimum site conditions for performing a particle removal
efficiency test.
5.2 Filter installation pre-testing inspection
Pre-inspection of filters and air handling units is necessary to determine whether a filter installation is
suitable for evaluation using this document. It is also used to gauge whether any potentially hazardous
conditions exist that would exclude or restrict access to the air handling unit.
Items provided in Annex A are some common items that may be reviewed during pre-testing inspection.
5.3 Approval for testing
Once the pre-testing inspection has been completed and the filter installation determined to be suitable
for testing, then the “approval for testing form” should be completed and signed by representatives of
the building owner or manager and the company performing the testing. A suitable form is shown in
Annex B.
6 Test procedure
6.1 Air velocity
Air velocity through the filter installation should be maintained constant for the duration of the test.
This is possible if the fan speed is controllable through variable frequency drive (VFD) or variable air
volume (VAV) boxes and other modulating dampers are not allowed to adjust. In addition, the percentage
of outside air in the supply air should also be kept constant to reduce fluctuations in particle count that
would influence the test results.
The air velocity at the face of the filters should be measured using the instrument identified in 4.5. Air
velocity measurements can be taken either upstream or downstream of the filters, but downstream is
recommended. Since air velocity can vary significantly over the area of a filter installation, sampling
points should be chosen such that measurements are taken at a minimum of 25 % of the filters and
are distributed uniformly over the area of the filter installation. The measurement device should be
extended away from turbulence caused by personnel or other obstructions. The velocity coefficient of
variation (C ) (see 9.3) should be less than 25 %.
v
Air velocity measurements should be conducted as close in time to resistance to airflow and removal
efficiency testing as possible. This is to ensure that the system air velocity does not change significantly
between the time of the velocity measurements and the time of the resistance to airflow and removal
ISO 29462:2022(E)
efficiency tests. Air velocity measurements shall be conducted both before and after the removal
efficiency testing, with the velocity measurements averaged.
EXAMPLE
st
1 test: velocity measurement [average velocity = 2,0 m/s (394 ft/min)]
nd
2 test: resistance to airflow measurements
rd
3 test: removal efficiency testing
th
4 test: velocity measurements [average velocity = 2,2 m/s (433 ft/min)]
In this EXAMPLE, the reported average velocity would be 2,1 m/s (414 ft/min).
More frequent velocity measurements can be taken in systems exhibiting a high degree of variability in
velocity over time.
6.2 Relative humidity (RH)
The instrument(s) identified in 4.6 should be used for these measurements. The RH of the air passing
through the filter installation is recommended to be within the range of the particle counter and/or
the RH measurement device used for the duration of the test. If system efficiency is being determined,
the RH should be measured and recorded at the locations of the upstream and downstream probes.
If measuring filter efficiency, the RH should be measured and recorded at one of the locations of the
upstream or downstream probes. In addition, the RH should be recorded at the particle counter
location. Wet-bulb temperature measurements referenced to the dry bulb temperature taken at the
same time may be used in lieu of RH measurements.
6.3 Temperature
The instrument(s) identified in 4.7 should be used for this measurement. The temperature of the air
passing through the filter installation sho
...