SIST EN ISO 29461-2:2022

SLOVENSKI STANDARD
oSIST prEN ISO 29461-7:2021
01-september-2021
Zračni filtrski sistemi rotacijskih strojev - Preskusne metode - 7. del: Preskus
vzdržljivosti filtrskih elementov v okolju z meglo in sparino (ISO/DIS 29461-7:2021)
Air filter intake systems for rotary machinery - Test methods - Part 7: Filter element
endurance test in fog and mist environments (ISO/DIS 29461-7:2021)
Systèmes de filtration d'air d'admission pour machines tournantes - Méthodes d'essai -
Partie 7: Essai d'endurance d'élément filtrant en brouillard et environnement brumeux
(ISO/DIS 29461-7:2021)
Ta slovenski standard je istoveten z: prEN ISO 29461-7
ICS:
29.160.99 Drugi standardi v zvezi z Other standards related to
rotacijskimi stroji rotating machinery
oSIST prEN ISO 29461-7:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 29461-7:2021

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oSIST prEN ISO 29461-7:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 29461-7
ISO/TC 142 Secretariat: UNI
Voting begins on: Voting terminates on:
2021-07-20 2021-10-12
Air intake filter systems for rotary machinery — Test
methods —
Part 7:
Filter element endurance test in fog and mist
environments
Systèmes de filtration d'air d'admission pour machines tournantes — Méthodes d'essai —
Partie 7: Essai d'endurance d'élément filtrant en brouillard et environnement brumeux
ICS: 29.160.99
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
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BEING ACCEPTABLE FOR INDUSTRIAL,
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STANDARDS MAY ON OCCASION HAVE TO
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WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 29461-7:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021

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oSIST prEN ISO 29461-7:2021
ISO/DIS 29461-7:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2021 – All rights reserved

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oSIST prEN ISO 29461-7:2021
ISO/DIS 29461-7:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
5 General requirements . 4
6 Test condition . 4
6.1 Test air . 4
6.2 Test water . 5
7 Test rig and equipment . 5
7.1 Test rig . 5
7.2 Water spray device . 6
7.3 Humidifying device . 6
7.4 Water collecting groove . 6
8 Qualification of test rig and apparatus . 6
8.1 Pressure system test . 6
8.2 Air leakage test. 6
8.3 Air velocity uniformity in the test duct . 6
8.4 Pressure drop of test duct with no test filter installed . 6
8.5 Stability of wet environment . 6
8.6 Water fog concentration and sedimentation check . . 7
8.7 Water tightness test with no test filter installed . 7
8.8 Water droplets size distributions . 7
8.9 Summary of qualification requirements . 8
8.10 Apparatus maintenance . 8
9 Test procedure . 8
9.1 Preparation of filter to be tested. 8
9.2 Initial pressure drop . 9
9.3 Test procedure for water endurance performance of filter elements . 9
9.3.1 General. 9
9.3.2 Wet equilibrium pretreatment . 9
9.3.3 Water fog test . 9
9.4 Water penetration ratio .10
10 Test report .10
10.1 General .10
10.2 Interpretation of test reports .10
10.3 Summaries of test results .11
10.4 Water fog mass and pressure drop .12
10.5 Marking .12
Annex A (informative) Resistance to air flow and water generation mass calculation .13
Annex B (informative) Water endurance test for vertical installed air filters .14
Annex C (informative) Water endurance of air filter elements without wet equilibrium
pretreatment .16
Annex D (normative) Water penetration ratio test .18
Annex E (informative) Leak detection and first water droplet detection procedure .19
Annex F (informative) Examples of completed test reports .22
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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.
A list of all parts in the ISO 29461 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.
iv © ISO 2021 – All rights reserved

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Introduction
ISO 29461 series of standards will provide a way to compare these products in a similar method and
define what criteria are important for air intake filter 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.
Air intake filter system of rotary machinery is an important part of the whole gas turbine and air
compressor systems. It usually consists of filter elements with a suitable way to be installed. The
operating environment of rotary machinery including gas turbine and compressor and their air intake
filtration units are complicated and challenging. Air filters intercept water mist and droplets when
air pass through the air filter unit in case the equipment is working in rainy, fog, haze or other high
humidity environment or local production environment which contains large amount of water vapour,
for example the cooling tower. If excessive water holds up, the performance of filters may be affected,
pressure drop raises up rapidly, even causes shut down in severe cases.
Reliability and non-break down operation of rotary machinery is regarded as top priority for end user,
the pressure drop raises up rapidly in high humidity conditions is usually their main concern. There are
rotary machinery operating accidents caused by high humidity conditions all over the world, no matter
it’s inland or along the river or coastal.
To meet the requirements of production and operation, water endurance performance of air filter
elements shall be considered besides assessing the performance of initial pressure drop, filtration
efficiency and dust-holding capacity, especially the air filter elements are used in high-humidity
environments or intake air contains a large quantity of liquid droplets.
This document provides a water endurance test method for filter elements and can be used for
evaluating performance variation trend of filter elements when encounter water and fog. This standard
can be used for:
— product development for filter manufacturers;
— supplier selection for end users;
— development of water endurance media by media manufacturers.
This document provides a repeatable, easy to conduct and economic test method, which shall be applied
for pulse-jet cleaning filter elements, and also for filter elements for general ventilation.
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oSIST prEN ISO 29461-7:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 29461-7:2021(E)
Air intake filter systems for rotary machinery — Test
methods —
Part 7:
Filter element endurance test in fog and mist
environments
1 Scope
This part of ISO 29461 specifies general test requirements, test rig and equipment, test materials, test
procedure and report for determining water endurance performance of air filter elements used in air
intake filter systems for rotary machinery such as stationary gas turbines, compressors and other
stationary internal combustion engines.
The test evaluates water endurance performance of air filter elements under laboratory conditions.
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 water endurance and lifetime.
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 29464:2017, Cleaning of air and other gases — Terminology
ISO 16890-2:2016, Air filters for general ventilation — Part 2: Measurement of fractional efficiency and air
flow resistance
ISO 29461-1, Air intake filter systems for rotary machinery — Test methods — Part 1: Static filter elements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 24964 and the following apply.
ISO and IEC maintain terminological 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 Air flow and pressure drop
3.1.1
air flow rate
volume of air passing through the filter per unit time
[SOURCE: ISO 29464:2017, 3.1.24]
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3.1.2
rated flow
flow rate through a test device, either as stated by the manufacturer for defined conditions of use or as
agreed between the interested parties for a particular installation
[SOURCE: ISO 29464:2017, 3.1.27]
3.1.3
test air flow rate
volumetric airflow rate used for testing
[SOURCE: ISO 29464:2017, 3.3.2]
3.1.4
pressure drop
pressure differential across the filter element at the test airflow rate
[SOURCE: ISO 29464:2017, 3.1.36]
3.1.5
initial pressure drop
pressure drop of the clean filter operating at the test airflow rate
[SOURCE: ISO 29464:2017, 3.3.17]
3.1.6
final test pressure drop
maximum pressure drop of the filter up to which the filtration performance is measured
[SOURCE: ISO 29464:2017, 3.3.15]
3.1.7
final test pressure drop recommended
maximum operating pressure drop of the filter to terminate the test as recommended at rated airflow
3.2 Filters
3.2.1
test device
filter element being subjected to performance testing
[SOURCE: ISO 29464:2017, 3.1.38]
3.2.2
filter element
structure made of the filtering material, its supports and its interfaces with the filter housing
[SOURCE: ISO 29464:2017, 3.2.77]
3.2.3
upstream
U/S
area or region from which fluid flows as it enters the test device
[SOURCE: ISO 29464:2017, 3.1.39]
3.2.4
downstream
D/S
area or region into which fluid flows on leaving the test device
[SOURCE: ISO 29464:2017, 3.1.11]
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3.2.5
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 pulse or other means in order to fully, or partially, retrieve its initial performance
(pressure drop and efficiency)
[SOURCE: ISO 29464:2017, 3.3.12]
3.2.6
pulse-jet filter
cleanable air filter, that typically is cleaned with air jet pulse to provide a longer service life
[SOURCE: ISO 29464:2017, 3.3.11]
3.3
test duration
period of reaching a certain pressure drop or other termination conditions to end the test
3.4 Test materials
3.4.1
water fog
water droplets and mist generated by water spray device
3.4.2
saturated air
air that contains the maximum amount of water vapour it can hold at its temperature and pressure
3.4.3
water fog mass concentration
mass of liquid water droplets per unit volume of air
4 Symbols and abbreviated terms
For the application of this document, the following symbols and abbreviated terms apply.
3
c
water fog mass concentration, g/m
wm
d
saturated wet air moisture content, g/kg
d
ambient air moisture content, g/kg
0
m
water mass penetrated through tested filter at the end of test, kg
p
m
total water fog generation amount, kg
tot
m
sedimentary water mass upstream of filter, kg
u
m
total water fog generation amount per hour, kg/h
wm
m
water fog generation amount per hour at saturated humidifying air, kg/h
wm, 1
m
water fog generation amount per hour, kg/h
wm, 2
p atmospheric pressure, Pa
absolute air pressure upstream of filter, Pa
p
a
partial vapour pressure of water in air, Pa
p
w
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saturated vapour pressure of humidifying air, Pa
p
ws
3
q
volumetric flow of non-humidifying air, m /h
v
t
temperature downstream of filter, °C
d
t
dry bulb temperature of ambient air, °C
0
t
temperature upstream of filter, °C
u
t
wet bulb temperature of ambient air, °C
wb
T
testing time, min
T
total testing time, min
tot
filter initial pressure drop at the test airflow rate, Pa
Δp
b
filter final test pressure drop at the test airflow rate, Pa
Δp
f
filter pressure drop at the test airflow rate at the T time after spraying, Pa
Δp
T
η
water penetration ratio
p
ρ 3
ambient air density, kg/ m
3
ρ
air density upstream of filter, kg/m
a
3
ρ
saturated wet air density, kg/m
s
ϕ
relative humidity, %
ϕ
relative humidity upstream of filter, %
u
ϕ
relative humidity downstream of filter, %
d
DEHS liquid (DiEthylHexylSebacate) used for generating the DEHS test aerosol
ISO International Organization for Standardization
5 General requirements
Air 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 water endurance test 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.
The test client can refer to the test results to rank the water endurance performance of multiple
candidate filters.
6 Test condition
6.1 Test air
Room air or outdoor air is used as the test air source. The air temperature shall be in the range of 10 °C
to 38 °C (before wet equilibrium pretreatment). The exhaust flow shall be discharged outdoors, indoors
or re-circulated. Filtration of the exhaust flow is recommended when test aerosol or loading dust may
be present.
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6.2 Test water
The test water PH value shall be in the range of 6 to 8, alkalinity shall be no more than 50 mg/l, full
hardness shall be no more than 70 mg/l. The temperature of test water shall not be higher than the
temperature of test air.
7 Test rig and equipment
7.1 Test rig
The test rig consists of several square duct sections with typical 610 mm × 610 mm nominal inner
dimensions except for the section where the filter is installed. This section has nominal inner dimensions
between 616 mm and 622 mm. The length of this duct section shall be at least 1,1 times the length of the
filter, with a minimum length of 1,5 m. Schematic diagram of the test rig is shown in Figure 1.
The test rig can be operated either in a negative or positive pressure airflow arrangement, and negative
pressure operation is recommended. The test duct must be sealed well to avoid water fog leakage if
positive pressure operated. Recommend a condensed water borehole at the lowest point in the fan
housing in the event of formation of condensation.
The duct material shall be electrically conductive and electrically grounded and shall have a smooth
interior finish and be sufficiently rigid to maintain its shape at the operating pressure. Smaller parts of
the test duct could be made in glass or plastic to see the filter and equipment. Provision of windows to
allow monitoring of test progress is desirable.
Key
A duct section of the test rig (inlet plenum) 7 example of water droplet size instrument location
B upstream duct section of the test rig 8 upstream pressure measuring point
C duct section of filter to be tested 9 upstream water collecting groove
D diameter of recirculated duct 10 filter to be tested
E downstream duct section of the test rig 11 midstream water collecting groove
downstream measuring point of temperature and
F recirculated duct section of the test rig 12
humidity
1 HEPA filter 13 downstream pressure measuring point
2 humidifying device 14 downstream water collecting groove
3 water flow mass metering device 15 final filter- eliminate water
4 water flow mass metering device 16 frequency converted fan
5 water spray device 17 air flow measuring point
upstream measuring point of temperature and
6
humidity
Figure 1 — Schematic diagram of the test rig
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7.2 Water spray device
Water spray device is used to generate uniform water fog continuously to feed the filter to be tested
during the test.
Two-fluid nozzle is recommended and the spraying direction with respect to the inlet airflow shall be
the same. The distance between the nozzle orifices and the duct section of filter to be tested shall be no
less than 1 m.
Water fog particle size can be adjusted by compressed air and water flow velocity. The cumulative
volume of water fog particles in the size range of 5 μm to 30 μm shall be more than 90 % of the total
water fog volume.
The water fog mass flow shall be controlled precisely, the deviation shall not exceed 3 % of the measured
value, which shall meet the requirements of 8.6.
Other types of water spray devices, such as ultrasonic humidifier, nozzle humidifier, can be used if these
devices can achieve the same performance.
7.3 Humidifying device
The humidifying device shall maintain the required humidity in the test duct, which can be used for wet
equilibrium pretreatment. The optional humidifying devices, such as ultrasonic humidifier, atomizer,
shall meet the requirements of 8.5.
7.4 Water collecting groove
The water collecting grooves shall be installed at the bottom of upstream and downstream of tested
filter to collect water during the test.
8 Qualification of test rig and apparatus
8.1 Pressure system test
Carry out pressure system test in accordance with ISO 16890-2, 8.2.1.
8.2 Air leakage test
Carry out air leakage test in accordance with ISO 16890-2, 8.2.8.
8.3 Air velocity uniformity in the test duct
Carry out the test of air velocity uniformity in the test duct in accordance with ISO 16890-2, 8.2.9.
8.4 Pressure drop of test duct with no test filter installed
Carry out the test of pressure drop of test duct with no test filter installed in accordance with
ISO 16890-2, 8.2.12.
8.5 Stability of wet environment
The temperature measuring instrument used shall be capable of measuring temperature with an
accuracy of ±1 °C. The relative humidity measuring instrument used shall be capable of measuring
relative humidity with an accuracy of ±2 %. The temperature and relative humidity measuring
instruments shall be calibrated annually.
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3
When test air flow rate is 3 400 m /h, turn on humidifying device until the measuring relative humidity
of upstream and downstream test duct exceed 95 %. Record the temperature and relative humidity at
the first time.
Record the temperature and relative humidity of upstream and downstream test duct every 2 min. The
total test time is 30 min.
The relative humidity of upstream and downstream shall always exceed 95 % du
...