EN ISO 29461-1:2013

SLOVENSKI STANDARD
01-september-2013
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Air intake filter systems for rotary machinery - Test methods - Part 1: Static filter
elements (ISO 29461-1:2013)
Prüfmethoden für Luftfiltereinlasssysteme von Rotationsmaschinen und stationäre
Verbrennungsmaschinen - Teil 1: Testmethoden und Klassifizierung von statischen
Filterelementen (ISO 29461-1:2013)
Systèmes de filtration d'air d'admission pour machines tournantes - Méthodes d'essai -
Partie 1: Éléments filtrants pour filtres statiques (ISO 29461-1:2013)
Ta slovenski standard je istoveten z: EN ISO 29461-1:2013
ICS:
29.160.99 Drugi standardi v zvezi z Other standards related to
rotacijskimi stroji rotating machinery
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 29461-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2013
ICS 29.160.99
English Version
Air intake filter systems for rotary machinery - Test methods -
Part 1: Static filter elements (ISO 29461-1:2013)
Systèmes de filtration d'air d'admission pour machines Luftfiltereinlasssysteme von Rotationsmaschinen -
tournantes - Méthodes d'essai - Partie 1: Éléments filtrants Prüfverfahren - Teil 1: Statische Filterelemente (ISO 29461-
pour filtres statiques (ISO 29461-1:2013) 1:2013)
This European Standard was approved by CEN on 1 March 2013.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
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Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 29461-1:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 29461-1:2012) has been prepared by Technical Committee ISO/TC 142 "Cleaning
equipment for air and other gases" in collaboration with Technical Committee CEN/TC 195 “Air filters for
general air cleaning” 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 October 2013, and conflicting national standards shall be withdrawn at
the latest by October 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 29461-1:2013 has been approved by CEN as EN ISO 29461-1:2013 without any modification.

INTERNATIONAL ISO
STANDARD 29461-1
First edition
2013-04-01
Air intake filter systems for rotary
machinery — Test methods —
Part 1:
Static filter elements
Systèmes de filtration d’air d’admission pour machines tournantes —
Méthodes d’essai —
Partie 1: Éléments filtrants pour filtres statiques
Reference number
ISO 29461-1:2013(E)
©
ISO 2013
ISO 29461-1:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, 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
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
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Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 29461-1:2013(E)
Contents Page
Foreword .v
0 Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.2 Velocity. 2
3.3 Efficiency . 2
3.5 Pressure drop (differential pressure) . 3
3.6 Filter area . 3
3.7 Filters . 3
3.8 Test aerosol . 4
3.9 Test dust . 5
3.10 Particle sampling . 5
3.11 Particle shedding . 5
4 Symbols and abbreviated terms . 6
5 General requirements . 8
6 Test rig and equipment . 8
6.1 Test condition . 8
6.2 Test rig . 8
6.3 DEHS test aerosol generation .12
6.4 Aerosol sampling system .13
6.5 Flow measurement .14
6.6 Particle counter .14
6.7 Differential pressure measuring equipment .15
6.8 Dust feeder .15
6.9 Diluter equipment .17
7 Qualification of test rig and apparatus .18
7.1 General .18
7.2 Air velocity uniformity in the test duct .18
7.3 Aerosol uniformity in the test duct.19
7.4 Particle counter sizing accuracy .20
7.5 Particle counter zero test .20
7.6 Particle counter overload test .20
7.7 100 % efficiency test .21
7.8 Zero % efficiency test .21
7.9 Aerosol generator response time .21
7.10 Dilution ratio .22
7.11 Correlation ratio .22
7.12 Pressure drop checking .23
7.13 Dust feeder airflow rate .23
7.14 Reference filter check .24
7.15 Summary of qualification requirements .25
7.16 Apparatus maintenance .25
8 Test materials .26
8.1 Test air .26
8.2 Test aerosol .26
8.3 Loading dust .27
8.4 Final filter .27
9 Test procedure .27
9.1 Preparation of filter to be tested.28
9.2 Initial pressure drop .28
ISO 29461-1:2013(E)
9.3 Initial particulate efficiency measurement.28
9.4 Conditioning test .32
9.5 Dust loading .32
10 Uncertainty calculation of the test results .33
10.1 Particulate efficiency for medium efficiency filters (initial particulate efficiency:
35 ≤ E ≤ 85 % at 0,4 μm).33
10.2 Particulate efficiency for high efficiency filters (initial particulate efficiency >85 % at
0,4 μm) .34
10.3 Gravimetric efficiency .36
11 Reporting .36
11.1 General .36
11.2 Interpretation of test reports .37
11.3 Summary .38
11.4 Efficiency .40
11.5 Pressure drop and airflow rate .40
11.6 Marking .40
Annex A (normative) Conditioning test procedure .47
Annex B (informative) Shedding from filter elements .51
Annex C (informative) Commentary .53
Annex D (normative) Pressure drop calculation .57
Annex E (normative) Net Area Calculation .59
Bibliography .66
iv © ISO 2013 – All rights reserved

ISO 29461-1:2013(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.
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 29461-1 was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and other gases.
ISO 29461 consists of the following parts, under the general title Air intake filter systems for rotary
machinery — Test methods:
— Part 1: Static filter elements
Cleanable (pulse jet) and surface loading filters, mechanical integrity of filter elements, in situ testing,
marine and offshore environment filter systems, and cleanable (pulse Jet) filter elements will form the
subjects of future parts.
ISO 29461-1:2013(E)
0 Introduction
0.1  Filters in power generating/compressor applications
In rotating machinery applications, the filtering system, typically a set of filter elements arranged in
a suitable manner, are an important part of the whole turbine/compressor system. The development
of turbine machinery used for energy production or others has led to more sophisticated equipment
and therefore the importance of good protection of these systems has become more important in the
recent years. It is known that particulate contamination can deteriorate a turbine power system quite
substantially if not taken care of.
This event is often described as “erosion”, “fouling” and “hot corrosion” where salt and other corrosive
particles are known as potential problems. Other particulate matters may also cause significant
reduction of efficiency of the systems. It is important to understand that air filter devices in such systems
are located in various environmental conditions. The range of climate and particulate contamination is
very wide, ranging from deserts to humid rain forests to arctic environments. The requirements on
these filter systems are obviously different depending on where they will be operating.
ISO 29461 has based the performance of the air intake filter systems not only upon heavy dust collection
but also particulate efficiency in a size range that is considered to be the problematic area for these
applications. Both ultra-fine and fine particles, as well as larger particles, should be considered
when evaluating turbine fouling. In typical outdoor air, ultra-fine and fine particles in the size range
from 0,01 μm to 1 μm contribute to >99 % of the number concentration and to >90 % of the surface
contamination. The majority of the mass normally comes from larger particles (>1,0 μm).
Turbo-machinery filters comprise a wide range of products from filters for very coarse particles to
filters for very fine, sub-micron particles. The range of products varies from self-cleaning to depth and
surface loading systems. The filters and the systems have to withstand a wide temperature and humidity
range, very low to very high dust concentration and mechanical stress. The shape of products existing
today can be of many different types and have different functions such as droplet separators, coalescing
products, filter pads, metal filters, inertial filters, filter cells, bag filters, panel-type, self-cleanable and
depth loading filter cartridges and pleated media surface filter elements.
ISO 29461 will provide a way to compare these products in a similar way and define what criteria are
important for air filter intake systems for rotary machinery performance protection. The performance
of products in this broad range must be compared in a good manner. Comparing different filters and
filter types must be done with respect to the operating conditions they finally will be used in.
For instance, if a filter or a filter system is meant to operate in an extreme, very dusty environment, the
real particulate efficiency of such a filter cannot be predicted because the dust loading of the filter plays
an important role. ISO 29461-2 will address the performance of cleanable and surface loading filters.
0.2  Filtration characteristics
Initiatives to address the potential problems of particle re-entrainment, shedding and the in-service
charge neutralization characteristics of certain types of media have been included in Annexes A and B.
Certain types of filter media rely on electrostatic effects to achieve high efficiencies at low resistance
to airflow. Exposure to some types of challenge, such as combustion particles or other fine particles,
may inhibit such charges with the result that filter performance suffers. The normative test procedure,
described in Annex A, provides techniques for identifying this type of behaviour. This procedure is used to
determine whether the filter particulate efficiency is dependent on the electrostatic removal mechanism
and to provide quantitative information about the importance of the electrostatic removal. The procedure
was selected because it is well established, reproducible, relatively fast and easy to perform.
In an ideal filtration process, each particle would be permanently arrested at the first contact with a
filter fibre, but incoming particles may impact on a captured particle and dislodge it into the air stream.
Fibres or particles from the filter itself could also be released, due to mechanical forces. From the user’s
point of view it might be important to know this, see Annex B.
vi © ISO 2013 – All rights reserved

ISO 29461-1:2013(E)
Filters with a low initial or conditioned particulate efficiency (<35 %) for sub-micron particles (0,4 μm)
that do not increase their efficiency during the operation will typically not provide any major protection
for the operating machinery when challenged with typical atmospheric aerosols where the majority of
particles are smaller than 1,0 μm. However, in some cases with aerosols having a dominant fraction of
coarse particles, filters with low efficiencies at sub-micron particles can serve as a protection for later
filter stages and can also have a higher average particulate efficiency (e.g. surface loading filters) at
0,4 μm due to the dust loading. Therefore a gravimetric test can provide some information about capacity
and gravimetric efficiency for those aerosols. In general, a lower total filtration level than 35 % at 0,4 μm
should not be recommended for an air intake filter system for rotary machinery when the aerosol loading
of the filters are not contributing to a significant increase of the efficiency during the operation.
0.3  Organization of ISO 29461
The methods and procedures for determining particulate efficiency, pressure drop and the corresponding
reporting formats are the same for all types of static filter element.
The test methods concerning particulate efficiency, pressure drop and reported values are the same for all
filters, except for loading characteristics and cleaning procedure, which are different for cleanable surface
loading filters. These filters incorporate cleaning procedures and have different loading characteristics;
therefore, they require appropriately modified test methods, which will be defined in Part 2.
Part 3 will provide methods for determining the mechanical integrity of filters under conditions that
may be encountered in abnormal operating environments.
Part 4 will describe methods of testing installed filters under in-service operating conditions (in situ testing).
Part 5 will cover test methods for the specific requirement of offshore and marine application, and
specify methods for determining the sea salt removal efficiency of individual filters and/or complete
filter systems.
Part 6 will cover test methods for cleanable filter elements, and will not cover the system testing
(e.g. cleaning device) as in Part 2.
This part of ISO 29461 describes the test methods for static filter units, typically of the depth loading type
(see definitions 3.43 and 3.44). All filters can be tested in the same manner, thus obtaining comparable
results. However, for surface loading filters, reverse pulse filters, marine and offshore filter systems, as
well as other filter systems that are not regarded as static filter units, the appropriate part shall be used.
For multi-stage systems that use a number of components (e.g. equipment for cleaning, filters), this part
of ISO 29461 may be used as long as the qualification requirements of the test rig can be fulfilled. In
cases where this is not possible, Part 4 (in situ testing) procedures may be applied.
INTERNATIONAL STANDARD ISO 29461-1:2013(E)
Air intake filter systems for rotary machinery — Test
methods —
Part 1:
Static filter elements
1 Scope
ISO 29461 specifies methods and procedures for determining the performance of particulate air filters
used in air intake filter systems for rotary machinery such as stationary gas turbines, compressors and
other stationary internal combustion engines. It applies to air filters having an initial particle efficiency
up to 99,9 % with respect to 0,4 µm particles. Filters with higher initial particle efficiencies are tested
and classified according to other standards (e.g. EN 1822). These procedures are intended for filters
3 3 3 3
which operating at flow rates within the range 0,25 m /s (900 m /h) up to 1,67 m /s (6000 m /h).
This part of ISO 29461 refers to static (barrier) filter systems but can be applied to other filter types and
systems in appropriate circumstances.
Two methods of determining the efficiency are used in this part of ISO 29461:
— particulate efficiency (measured with respect to particle number and size);
— gravimetric efficiency (percentage weighted mass removal of loading dust).
Also a flat sheet media sample or media pack sample from an identical filter is conditioned (discharged)
to provide information about the intensity of the electrostatic removal mechanism.
After determination of its initial particle efficiency, the untreated filter is loaded with dust in steps until its
final test pressure drop is reached. Information on the loaded performance of the filter is then obtained.
The performance results obtained in accordance with this part of ISO 29461 cannot be quantitatively
applied (by themselves) to predict performance in service with regard to efficiency and lifetime. Other
factors influencing performance to be taken into account are described in the annexes.
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 2854, Statistical interpretation of data — Techniques of estimation and tests relating to means and variances
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 12103-1, Road vehicles — Test dust for filter evaluation — Part 1: Arizona test dust
ISO 14644-3:2005, Cleanrooms and associated controlled environments — Part 3: Test methods
ISO 21501-1, Determination of particle size distribution — Single particle light interaction methods —
Part 1: Light scattering aerosol spectrometer
ISO 21501-4, Determination of particle size distribution — Single particle light interaction methods —
Part 4: Light scattering airborne particle counter for clean spaces
ISO 29461-1:2013(E)
ASHRAE 52.2:1999, Method of testing general ventilation air-cleaning devices for removal efficiency by
particle size
IEST-RP-CC014, Calibration and Characterization of Optical Airborne Particle Counters
JIS Z 8901:2006, Test powders and test particles
JACA No.37:2001, Guideline of Substitute Materials for DOP
3 Terms and definitions
3.1
test airflow rate
volumetric airflow rate used for testing
[Source: ISO 29464:2011; 3.1.106]
3.2 Velocity
3.2.1
filter face velocity
airflow rate divided by the filter face area
[Source: ISO 29464:2011, 3.1.84]
3.2.2
media velocity
airflow rate divided by the effective filtering area
Note 1 to entry: Expressed at an accuracy of three significant figures.
3.3 Efficiency
3.3.1
particulate efficiency
percentage particulate removal efficiency of the filter at specified particle sizes measured with a particle
counter in the range of 0,3 µm to 3,0 µm
3.3.2
initial efficiency
particulate efficiency of the clean filter operating at the test airflow rate
Note 1 to entry: A clean filter is a filter not exposed to any test aerosol or substance prior to the efficiency test.
3.3.3
minimum efficiency
lowest particulate efficiency of initial, conditioned or dust loaded efficiencies
3.3.4
conditioned efficiency
efficiency of the conditioned filter media (per Annex A) operating at an average media velocity
corresponding to the test airflow rate in the filter
3.3.5
gravimetric efficiency
A
weighted (mass) removal of loading dust after 50 g of dust load
2 © ISO 2013 – All rights reserved

ISO 29461-1:2013(E)
3.3.6
average gravimetric efficiency
A
avg
ratio of the total amount of loading dust retained by the filter to the total amount of dust fed up to final
test pressure drop
3.3.7
dust loaded efficiency
efficiency of the filter operating at test flow rate and after dust loadings up to final test pressure differential
3.4
penetration
ratio of the particle concentration detected downstream versus the concentration upstream of the filter
3.5 Pressure drop (differential pressure)
3.5.1
initial pressure drop
pressure drop of the clean filter operating at the test airflow rate
3.5.2
final test pressure drop
maximum pressure drop of the filter up to which the filtration performance is measured
3.5.3
final test pressure drop – recommended
maximum operating pressure drop of the filter as recommended by the manufacturer at rated airflow
3.6 Filter area
3.6.1
filter face area
frontal face area of the filter including the header frame
[Source: ISO 29464:2011, 3.1.83]
Note 1 to entry: Typical nominal values: 0,610 m × 0,610 m (24 in × 24 in).
3.6.2
effective filtering area
area of filter medium in the filter which collects dust
[Source: ISO 29464:2011; 3.1.79]
3.7 Filters
3.7.1
static filter
air filter that will be removed (exchanged) after it has reached its final test pressure drop and that is
not cleaned with jet pulses or other means in order to fully, or partially, retrieve its initial performance
(pressure drop and efficiency)
3.7.2
pulse jet filter
cleanable air filter, that typically is cleaned with air jet pulses to provide a longer service life
3.7.3
surface loading filter
filter in which the dust is collected on the surface of the filter medium
ISO 29461-1:2013(E)
3.7.4
depth loading filter
filter in which particles penetrate into the filter medium and are collected on the fibres in the depth of
the filter medium
3.7.5
low efficiency filter
air filter with an initial particulate efficiency at 0,4 µm particles in the range E < 35 %
3.7.6
medium efficiency filter
air filter with an initial particulate efficiency at 0,4 µm particles in the range 35 % ≤ E ≤ 85 %
3.7.7
high efficiency filter
air filter with an initial particulate efficiency at 0,4 µm particles in the range E ≥ 85 %
3.7.8
EPA filter
air filter with a particulate efficiency at most penetrating particle size (MPPS) in the range
85 % ≤ E ≤ 99,95 % (typically 0,05 µm to 0,3 µm size range)
3.7.9
final filter
air filter used to collect the loading dust passing through or shedding from the filter under test
[Source: ISO 29464:2011; 3.1.86]
3.7.10
charged filter
filter in which the medium is electrostatically charged or polarized
[Source: ISO 29464:2011; 3.1.75]
3.7.11
untreated filter
air filter not submitted to conditioning per Annex A
3.8 Test aerosol
3.8.1
test aerosol
aerosol used for determining the particulate efficiency of the filter
3.8.2
particle size
geometric diameter (equivalent spherical, optical or aerodynamic, depending on the context) of the
particles of an aerosol
[Source: ISO 29464:2011; 3.1.126]
3.8.3
mean diameter
geometric mean value of the upper and lower border diameters in a size range
3.8.4
particle number concentration
number of particles per unit volume of air
4 © ISO 2013 – All rights reserved

ISO 29461-1:2013(E)
3.8.5
neutralization
action of bringing the aerosol to a Boltzmann charge equilibrium distribution with bipolar ions
3.9 Test dust
3.9.1
loading dust
synthetic test dust
synthetic dust formulated specifically for determination of the test dust capacity and arrestance of air filters
3.9.2
test dust capacity
dust loading capacity
TDC
amount of loading dust held by the filter at final test pressure drop
3.10 Particle sampling
3.10.1
isokinetic sampling
technique for air sampling such that the probe inlet air velocity is the same as the velocity of the air
surrounding the sampling point
[Source: ISO 29464:2011; 3.1.144]
3.10.2
counting rate
number of counting events per unit time
[Source: ISO 29464:2011; 3.1.41]
3.10.3
correlation ratio
downstream particle concentration divided by the upstream particle concentration (measured
without filter)
[Source: ISO 29464:2011; 3.1.26]
3.11 Particle shedding
3.11.1
shedding
release to the airflow of particles due to particle bounce and re-entrainment effects and to the release
of fibres or particulate matter from the filter or filtering material
[Source: ISO 29464:2011; 3.1.150]
3.11.2
particle bounce
behaviour of particles that impinge on the filter without being retained
[Source: ISO 29464:2011; 3.1.121]
3.11.3
re-entrainment
release to the airflow of particles previously collected on the filter
[Source: ISO 29464:2011; 3.1.142]
ISO 29461-1:2013(E)
4 Symbols and abbreviated terms
A gravimetric efficiency after 50 g dust load, %
A average gravimetric efficiency %
avg
CL concentration limits of particulate counter
C coefficient of variation
V
C coefficient of variation in size range “i”
V,i
C mean of measuring points value for size range “i”
mean,i
CL lower confidence limit of particulate efficiency (95 % confidence level)
E
average lower confidence limit of particulate efficiency (95 % confidence level). Average
CL
E
value from repeated measurement cycles for one efficiency calculation
CL upper confidence limit (95 %) of number of particles downstream of the filter
Nd
CL lower confidence limit (95 %) of number of particles upstream of the filter
Nu
d geometric mean of a size range, µm
i
d lower border diameter in a size range, µm
l
d upper border diameter in a size range, µm
u
DR dilution ratio, when diluter is used
average particulate efficiency in a size range “i”
E
i
m mass passing the filter, g
m mass of dust downstream of the test filter, g
d
m mass of dust fed to filter in order to test gravimetric efficiency (50 g), g
m mass of dust that has passed the filter (the mass gain of final filter and the dust in the
p50
duct between the filter and the final filter) after 50 g of dust loading
m cumulative mass of dust fed to filter, g
tot
m mass of final filter before dust increment, g
m mass of final filter after dust increment, g
N number of points
N number of particles downstream of the filter
d
N number of particles in size range “i” downstream of the filter
d,i
average number of particles downstream of the filter
N
d
N number of particles upstream of the filter
u
N number of particles in size range “i” upstream of the filter
u,i
6 © ISO 2013 – All rights reserved

ISO 29461-1:2013(E)
average number of particles upstream of the filter
N
u
n exponent
p pressure, Pa
p absolute air pressure upstream of filter, kPa
a
p airflow meter static pressure, kPa
sf
q mass flow rate, kg/s
m
q airflow rate at filter, m /s
V
q airflow rate at airflow meter, m /s
Vf
R correlation ratio
R correlation ratio for size range “i”
i
T temperature upstream of filter, °C (°F)
T temperature at airflow meter, °C (°F)
f
t distribution variable
(/12−α )
U uncertainty, % units
v mean value of velocity
mean
δ standard deviation
ν number of degrees of freedom
ρ air density, kg/m
φ relative humidity upstream of filter, %
Δm dust increment, g
Δm mass gain of final filter, g
ff
Δp filter pressure drop, Pa
Δp Differential pressure, Pa
f
Δp filter pressure drop at air density 1,20 kg/m , Pa
1,20
ΔE difference in particulate efficiency between initial particulate efficiency (E ) of media
C 0
sample and conditioned efficiency (media samples) per Annex A
OPC optical particle counter
DEHS liquid (DiEthylHexylSebacate) used for generating the DEHS test aerosol
ANSI American National Standards Institute
ASHRAE American Society of Heating, Refrigerating and Air Conditioning Engineers
ASTM American Society for Testing and Materials
ISO 29461-1:2013(E)
CAS Chemical Abstracts
CEN European Committee for Standardization
EN European Standard
EUROVENT European Committee of Air Handling and Refrigeration Equipment Manufacturers
ISO International Organization for Standardization
5 General requirements
Static filter systems normally use multiple stages of coarse and fine filter elements to protect the machinery.
The scope of this part of ISO 29461 includes methods for performance testing of individual filter elements.
It does not include methods for the direct measurement of the performance of entire systems as installed
in service except in cases where they can meet the qualification criteria for the test assembly.
6 Test rig and equipment
6.1 Test condition
Room air or outdoor air may be used as the test air source. Relative humidity shall be in the range of
30 % to 70 % in the tests. The air temperature shall be in the range of 10 °C to 38 °C. The exhaust flow
may be discharged outdoors, indoors or re-circulated. Requirements of certain measuring equipment
may impose limits on the temperature of the test air.
Filtration of the exhaust flow is recommended when test aerosol, loading dust
...