ISO 21927-3:2021

INTERNATIONAL ISO
STANDARD 21927-3
Second edition
2020-05
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and
heat exhaust ventilators
Systèmes de contrôle de fumée et de chaleur —
Partie 3: Spécifications pour les ventilateurs mécaniques d'évacuation
des fumées et de la chaleur
Reference number
ISO 21927-3:2020(E)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 21927-3:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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ISO 21927-3:2020(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 Response delay (response time) . 2
4.1.1 Opening under wind load within a given time . 2
4.1.2 Opening under snow load within a given time . 3
4.2 Operational reliability . 3
4.2.1 General. 3
4.2.2 Application categories . 3
4.2.3 Motor rating . 3
4.3 Effectiveness of smoke/hot gas extraction . 4
4.3.1 General. 4
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test . 4
4.4 Resistance to fire . 4
4.5 Ability to open under environmental conditions . 4
4.5.1 Opening under wind load within a given time . 4
4.5.2 Opening under snow load within a given time . 4
4.6 Durability of operational reliability . 4
5 Testing, assessment and sampling methods. 4
5.1 General . 4
5.2 Test of response delay (response time) opening under wind, snow load within a
given time . 5
5.2.1 Wind load . 5
5.2.2 Snow load . 5
5.3 Operational reliability . 6
5.3.1 Application categories . 6
5.3.2 Motor rating . 6
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test . 6
5.5 Resistance to fire . 6
5.6 Ability to open under environmental conditions: opening under wind or snow
load within a given time . 6
5.7 Durability of operational reliability . 6
6 Marking, labelling and packaging . 7
Annex A (normative) Criteria to determine family of fans in order to select the sizes to be tested.8
Annex B (normative) Criteria to determine a family of motors in order to select the sizes to
be tested .28
Annex C (normative) Test method for the determination of fire resistance of powered
smoke and heat control ventilators (fans) .37
Annex D (normative) Test methods for electric motors to determine the impact of the
changes on the product characteristics .46
Annex E (normative) Test method for assessing the response delay and ability to open
under environmental conditions .51
Annex F (informative) Explanatory notes .52
Annex G (informative) General guidance for installation and maintenance .68
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ISO 21927-3:2020(E)

Bibliography .69
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ISO 21927-3:2020(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 21, Equipment for fire protection and fire
fighting, Subcommittee SC 11, Smoke and heat control systems and components.
This second edition cancels and replaces the first edition (ISO 21927-3:2006), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— amendment of the test apparatus.
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.
A list of all parts in the ISO 21927 series can be found on the ISO website.
© ISO 2020 – All rights reserved v

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ISO 21927-3:2020(E)

Introduction
Smoke and heat exhaust ventilation systems create a smoke-free layer above the floor by removing
smoke and, thus, improve the conditions for the safe escape and/or rescue of people and animals and
the protection of property and permit the fire to be fought while still in its early stages. They also
exhaust hot gases released by a fire in the developing stage.
The use of smoke and heat exhaust ventilation systems to create smoke-free areas beneath a buoyant
smoke layer has become widespread. Their value in assisting in the evacuation of people from
construction works, reducing fire damage and financial loss by preventing smoke logging, facilitating
firefighting, reducing roof temperatures and delaying the lateral spread of fire is firmly established.
For these benefits to be obtained, it is essential that smoke and heat exhaust ventilation systems be a
scheme of safety equipment intended to perform a positive role in a fire emergency.
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INTERNATIONAL STANDARD ISO 21927-3:2020(E)
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and heat exhaust
ventilators
1 Scope
This document specifies the product characteristics of powered smoke and heat control ventilators
(fans) intended to be used as part of a powered smoke and heat control ventilation system in
construction works.
It provides test and assessment methods of the characteristics and the conformance criteria of the test
assessment results.
This document applies to the following:
a) fans for smoke and heat control ventilation;
b) impulse/jet fans for smoke and heat control ventilation.
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 281, Rolling bearings — Dynamic load ratings and rating life
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5801, Fans — Performance testing using standardized airways
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60034-2-1, Rotating electrical machines — Part 2-1: Standard methods for determining losses and
efficiency from tests (excluding machines for traction vehicles)
IEC 60085, Electrical insulation — Thermal evaluation and designation
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
EN 1363-1, Fire resistance tests — Part 1: General Requirements
EN 13501-4, Fire classification of construction products and building elements — Part 4: Classification
using data from fire resistance tests on components of smoke control systems
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO 21927-3:2020(E)

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 http:// www .electropedia .org/
3.1
powered smoke and heat control ventilator
PSHC ventilator
smoke-ventilating fan that is suitable for handling smoke and hot gases for a specified time/
temperature profile
3.2
smoke reservoir
region within a building, limited or bordered by smoke curtains or structural elements, which retains a
thermally buoyant smoke layer in the event of a fire
3.3
powered roof ventilator
fan designed for mounting on a roof and with exterior weather protection
3.4
smoke reservoir ventilator
ventilator suitable for operation fully immersed in a smoke reservoir (3.2)
3.5
product family
physically similar fans using the same form of construction and materials throughout, with the same
methods of impeller construction, motor mounting and construction, and electrical connection in which
the following may vary across the range:
— overall dimensions of the fans; and/or
— the impeller diameter and width, hub size, blade length and number of blades of the impeller; and/or
— the motor details, as per 3.7
3.6
impulse/jet fans for smoke and heat control ventilation
fan used for producing a jet of air in a space and unconnected to any ducting
Note 1 to entry: The air jet may be used, for example, for adding momentum to the air within a duct, a tunnel or
other space, or for intensifying the heat transfer in a determined zone.
3.7
motor rating
maximum power that a motor delivers continuously without exceeding the allowable temperature rise
4 Requirements
4.1 Response delay (response time)
4.1.1 Opening under wind load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.1.
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ISO 21927-3:2020(E)

4.1.2 Opening under snow load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.2.
4.2 Operational reliability
4.2.1 General
Operational reliability of a PSHC ventilator (fan) shall be demonstrated by verification against
application categories and by verification of motor ratings.
4.2.2 Application categories
To demonstrate its operational reliability, a PSHC ventilator (fan) shall be verified against categories.
Table 1 shows the relevant method to allocate the results in the corresponding category.
Table 1 — Application categories
Clause of the test Application category Compliance criteria
method
5.3.1 Thermally insulated When tested in accordance with
Annex C:
— the outer surface temperature of
a thermal insulated fan shall not
increase by more than 180 K for any
individual value;
— the cooling air expelled from the
unit shall not exhibit an increase
of temperature of more than 180 K
from the initial room temperature.
5.3.1 Thermally uninsulated —
C.3.3 Installation inside the smoke reservoir —
C.3.3 Installation outside the smoke reservoir —
A.1 i) Horizontal direction of motor shaft —
A.1 i) Vertical direction of motor shaft —
A.1 n) Converter feed (driven by frequency —
converter)
A.1 n) Direct feed (no speed variation) —
C.4.2.1 Dual purpose use —
C.4.2.1, C.4.2.2 Emergency only use —
C.3.3 Ducted cooling air required —
4.2.3 Motor rating
Since the PSHC ventilator (fan) can be operated at different temperatures (current or emergency),
motors shall be selected for operation at the power required for normal ambient temperature and not
just for operation at high temperature.
Selection of the motors shall comply with the following requirements.
— Motors shall comply with the requirements of IEC 60034-1.
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ISO 21927-3:2020(E)

— Motor ratings shall be limited by the temperature rise for one class lower than the insulation class
of the motor, as defined in IEC 60085.
— The fan tested in accordance with 5.3.2 shall comply with the stability requirement in C.4.2.2.
4.3 Effectiveness of smoke/hot gas extraction
4.3.1 General
The effectiveness of smoke/hot gas extraction of the fan is the ability to continue to extract the required
volume flow at high temperature.
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test
The effectiveness of smoke/hot gas extraction is demonstrated by conformance with the performance
requirements in C.5, when tested according to 5.4.
4.4 Resistance to fire
The fan is shown to be functioning satisfactorily by its continued ability to provide the initial volume or
pressure within the defined limits in C.5, when tested according to 5.5.
The test result shall be classified in accordance with EN 13501-4.
4.5 Ability to open under environmental conditions
4.5.1 Opening under wind load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with 5.6.
4.5.2 Opening under snow load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with 5.6.
4.6 Durability of operational reliability
Durability of operational reliability is demonstrated by motor rating according to 4.2.3 when tested
according to 5.7.
5 Testing, assessment and sampling methods
5.1 General
PSHC ventilator (fan), tests shall be carried out in accordance with Annexes A, B, C and E.
For each test, a test report shall be prepared in accordance with Annex C.
A fan can be tested completely assembled with ancillaries, for example:
— flexible connection elements;
— anchors (fastenings for mounting to external structure);
— airflow operated dampers or external powered dampers;
— shock absorber (anti-vibration mount);
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ISO 21927-3:2020(E)

— sound absorber (silencer or acoustic attenuator);
— support construction (e.g. for powered roof or partition fans);
— thermal protection (e.g. PTC thermistor, Thermocouple, Pt100, etc.);
— ON-OFF switch and other electrical ancillaries (e.g. electrical safety box) which are directly mounted
on the fan;
— guide vanes;
— flow deflectors;
— a jet fan shall be tested completely assembled and suspended from a supporting construction in
accordance with the manufacturer’s installation instruction.
For testing of motors alone, tests shall be carried out and test reports prepared in accordance with
Annex D.
5.2 Test of response delay (response time) opening under wind, snow load within a
given time
5.2.1 Wind load
The fan shutter, flaps or louvers shall open in less than 30 s against a horizontally applied load of 200 Pa,
simulated by means of an additional fan blowing on the flap at a suitable velocity, or by any suitable
mechanical means when the fan is tested in accordance with Annex E and/or Annex C.
WARNING — For fans which use the air pressure from the fan to open flaps or louvers:
Due to the temperature rise, the density of air decreases resulting in a corresponding decrease
in the pressure developed. This pressure is needed to open the termination system (flaps or
louvers).
In this case, the laboratory shall perform the wind load test also during the high temperature test.
If fans selected according to Annex A and tested according to Annex C are intended for use with
external, air-pressure operated shutters, the combination shall also be tested with a wind load
according to Annex E.
The operating position can be considered as reached if the volume flow exhausted by the fan
working under wind loads did not decrease by more than 10 % of that exhausted by the fan
working without these loads.
If a fan intended for mounting on an external wall is fitted with external shutters, flaps or
louvers and/or is not protected from wind force acting against it by a deflector or cowl, it shall
be tested in accordance with this clause. Otherwise, the manufacture shall include a statement
in his instructions that suitable wind guarding shall be fitted by the installer.
5.2.2 Snow load
The fan shutter, flaps or louvers shall open in less than 30 s against a vertically applied load shown
in Table 2, simulated by any suitable mechanical means, when the fan is tested in accordance with
Annex E, at ambient temperature only.
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ISO 21927-3:2020(E)

Table 2 — Snow load classes
Class Load
Pa
SL 0 0
SL 125 125
SL 250 250
SL 500 500
SL 1 000 1 000
SL A A
The operating position can be considered as reached if the volume flow exhausted by the fan working
under snow loads did not decrease by more than 10 % of that exhausted by the fan working without
these loads.
Where the minimum angle of installation recommended by the supplier exceeds 45° from the
horizontal, the fan takes the classification SL 1 000 without a test; except where snow is prevented
from slipping from the fan, for example by wind deflectors. In this case, the fan shall be tested for a
snow load classification which shall not be less than SL = 2 000 · d, where d is the depth of snow, in
metres, which can be contained with the confines of the deflectors.
5.3 Operational reliability
5.3.1 Application categories
The relevant test methods are those indicated in Table 1 in 4.2.2.
5.3.2 Motor rating
The test method to be applied is in C.4.2.
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test
The test method is given in Annex C.
5.5 Resistance to fire
The test method is given in Annex C.
5.6 Ability to open under environmental conditions: opening under wind or snow load
within a given time
The test method is given in Annex E.
5.7 Durability of operational reliability
Durability of operational reliability is demonstrated by the test method given in 5.3.2.
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ISO 21927-3:2020(E)

6 Marking, labelling and packaging
The PSHC ventilator (fan) shall be marked with the following:
— the manufacturer’s name or trademark;
— the resistance to fire classification;
— a reference to this document and its year of its publication (i.e. ISO 21927-3:2020), followed by the
generic name of the product "powered smoke and heat control ventilator";
— the model/type;
— power requirements, e.g. power, current, voltage and rotational speed;
— the snow load class where applicable;
— the flow direction inside the fan (motor upstream, downstream or both);
— the direction of the motor shaft (vertical, horizontal or both);
— the minimum flow and maximum temperature of cooling air, where applicable;
— information about electrical connections of motor (e.g. Y or Δ);
— the following statement: "This powered smoke and heat control ventilator shall be installed as per
the manufacturer's instruction.";
— the manufacturer's installation instructions or a reference to a document held by the manufacturer
giving these instructions;
— the date of manufacture (month and year).
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ISO 21927-3:2020(E)

Annex A
(normative)

Criteria to determine family of fans in order to select the sizes to
be tested
A.1 Reduction of numbers of tests for PSHC ventilators forming a product range
It is not usually considered necessary to test every size of ventilator in a family of fans provided that the
following are tested and the family conforms to the rules given in A.3, A.4 and Annex B:
a) the fan with the most highly stressed impeller, and the ventilators with impellers in which the
individual stress in any component, weld or fastening is the highest, as appropriate, if not the same
(see A.4);
b) for fans with motors mounted in an enclosure which restricts the cooling, the worst case shall be
tested; this is the smallest free area of the motor enclosure or the smallest section of exit or entry
airway for cooling air;
c) at least two sizes of fans are tested at their highest rotational speed;
d) the fan with the smallest motor frame size to be used, except for fans where the impeller is not
mounted on the motor shaft and the motors are out of the airstream in ambient air and the cooling
of the motor is not affected by heat transfer from the ventilator or the ventilator construction;
e) if the highest impeller stress levels are determined by geometric similarity conditions from A.4.1,
sufficient sizes of fans to ensure that the impeller diameters of the range are from 0,8 to 1,27 of
those tested;
f) if the highest impeller stress levels are determined by the calculation methods in A.4.2, sufficient
sizes of fans to ensure that the impeller diameters of the range are from 0,63 to 1,27 of those tested;
NOTE The coefficients are taken from Renard Series R20 in accordance with several ISO standards. The
aim of the coefficients 0,8 or 0,63 and 1,27 is to validate fans down to 2 or 4 sizes smaller and up to 2 sizes
larger than the tested size. See Annex F for more information.
g) for a direct drive axial fan where the blade profile is not symmetrical and the fan may be supplied
with motor upstream or motor downstream, the fan shall be tested with motor downstream, which
is the worst case;
h) but if the fan range is intended to operate only with motor upstream, the tests can be performed in
...

INTERNATIONAL ISO
STANDARD 21927-3
Second edition
2021-05
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and
heat exhaust ventilators
Systèmes de contrôle de fumée et de chaleur —
Partie 3: Spécifications pour les ventilateurs mécaniques d'évacuation
des fumées et de la chaleur
Reference number
ISO 21927-3:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 21927-3:2021(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
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 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 21927-3:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
4 Requirements . 2
4.1 Response delay (response time) . 2
4.1.1 Opening under wind load within a given time . 2
4.1.2 Opening under snow load within a given time . 3
4.2 Operational reliability . 3
4.2.1 General. 3
4.2.2 Application categories . 3
4.2.3 Motor rating . 3
4.3 Effectiveness of smoke/hot gas extraction . 4
4.3.1 General. 4
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test . 4
4.4 Resistance to fire . 4
4.5 Ability to open under environmental conditions . 4
4.5.1 Opening under wind load within a given time . 4
4.5.2 Opening under snow load within a given time . 4
4.6 Durability of operational reliability . 4
5 Testing, assessment and sampling methods. 4
5.1 General . 4
5.2 Test of response delay (response time) opening under wind / snow load within
a given time . 5
5.2.1 Wind load . 5
5.2.2 Snow load . 6
5.3 Operational reliability . 6
5.3.1 Application categories . 6
5.3.2 Motor rating . 6
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test . 6
5.5 Resistance to fire . 6
5.6 Ability to open under environmental conditions: opening under wind or snow
load within a given time . 6
5.7 Durability of operational reliability . 6
6 Marking, labelling and packaging . 7
Annex A (normative) Criteria to determine the family of fans in order to select the sizes
to be tested. 8
Annex B (normative) Criteria to determine a family of motors in order to select the sizes
to be tested.29
Annex C (normative) Test method for the determination of fire resistance of powered
smoke and heat control ventilators (fans) .38
Annex D (normative) Test methods for electric motors to determine the impact of
the changes on the product characteristics .47
Annex E (normative) Test method for assessing the response delay and ability to open
under environmental conditions .52
Annex F (informative) Explanatory notes .53
Annex G (informative) General guidance for installation and maintenance .69
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ISO 21927-3:2021(E)

Bibliography .70
iv © ISO 2021 – All rights reserved

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ISO 21927-3:2021(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 21, Equipment for fire protection and fire
fighting, Subcommittee SC 11, Smoke and heat control systems and components.
This second edition cancels and replaces the first edition (ISO 21927-3:2006), which has been technically
revised. It also incorporates the Amendment ISO 21927-3:2006/Amd. 1:2010.
The main changes compared to the previous edition are as follows:
— amendment of the test apparatus;
A list of all parts in the ISO 21927 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.
© ISO 2021 – All rights reserved v

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ISO 21927-3:2021(E)

Introduction
Smoke and heat exhaust ventilation systems create a smoke-free layer above the floor by removing
smoke and, thus, improve the conditions for the safe escape and/or rescue of people and animals and
the protection of property and permit the fire to be fought while still in its early stages. They also
exhaust hot gases released by a fire in the developing stage.
The use of smoke and heat exhaust ventilation systems to create smoke-free areas beneath a buoyant
smoke layer has become widespread. Their value in assisting in the evacuation of people from
construction works, reducing fire damage and financial loss by preventing smoke logging, facilitating
firefighting, reducing roof temperatures and delaying the lateral spread of fire is firmly established.
For these benefits to be obtained, it is essential that smoke and heat exhaust ventilation systems be a
scheme of safety equipment intended to perform a positive role in a fire emergency.
vi © ISO 2021 – All rights reserved

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INTERNATIONAL STANDARD ISO 21927-3:2021(E)
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and heat exhaust
ventilators
1 Scope
This document specifies the product characteristics for powered smoke and heat control ventilators
(fans) intended to be used as part of a powered smoke and heat control ventilation system in
construction works.
It provides test and assessment methods of the characteristics and the conformance criteria of the test
assessment results.
This document applies to the following:
a) fans for smoke and heat control ventilation;
b) impulse/jet fans for smoke and heat control ventilation.
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 281, Rolling bearings — Dynamic load ratings and rating life
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5801, Fans — Performance testing using standardized airways
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60034-2-1, Rotating electrical machines — Part 2-1: Standard methods for determining losses and
efficiency from tests (excluding machines for traction vehicles)
IEC 60085, Electrical insulation — Thermal evaluation and designation
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
EN 1363-1, Fire resistance tests — Part 1: General Requirements
EN 13501-4, Fire classification of construction products and building elements — Part 4: Classification
using data from fire resistance tests on components of smoke control systems
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
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ISO 21927-3:2021(E)

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 http:// www .electropedia .org/
3.1
powered smoke and heat control ventilator
PSHC ventilator
smoke-ventilating fan that is suitable for handling smoke and hot gases for a specified time/temperature
profile
3.2
smoke reservoir
region within a building, limited or bordered by smoke curtains or structural elements, which retains a
thermally buoyant smoke layer in the event of a fire
3.3
powered roof ventilator
fan designed for mounting on a roof and with exterior weather protection
3.4
smoke reservoir ventilator
ventilator suitable for operation fully immersed in a smoke reservoir (3.2)
3.5
product family
physically similar fans using the same form of construction and materials throughout, with the same
methods of impeller construction, motor mounting and construction, and electrical connection in which
the following may vary across the range:
— overall dimensions of the fans; and/or
— the impeller diameter and width, hub size, blade length and number of blades of the impeller; and/
or
— the motor details, as per 3.7
3.6
impulse/jet fans for smoke and heat control ventilation
fan used for producing a jet of air in a space and unconnected to any ducting
Note 1 to entry: The air jet may be used, for example, for adding momentum to the air within a duct, a tunnel or
other space, or for intensifying the heat transfer in a determined zone.
3.7
motor rating
maximum power that a motor delivers continuously without exceeding the allowable temperature rise
4 Requirements
4.1 Response delay (response time)
4.1.1 Opening under wind load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.1.
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ISO 21927-3:2021(E)

4.1.2 Opening under snow load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.2.
4.2 Operational reliability
4.2.1 General
Operational reliability of a PSHC ventilator (fan) shall be demonstrated by verification against
application categories and by verification of motor ratings.
4.2.2 Application categories
To demonstrate its operational reliability, a PSHC ventilator (fan) shall be verified against certain
categories.
Table 1 shows the relevant method to allocate the results in the corresponding category.
Table 1 — Application categories
Subclause of the test
method (within ISO Application category Conformance criteria
21927-3)
5.3.1 Thermally insulated When tested in accordance with
Annex C:
— the outer surface temperature of
a thermal insulated fan shall not
increase by more than 180 K for any
individual value;
— the cooling air expelled from the
unit shall not exhibit an increase
of temperature of more than 180 K
from the initial room temperature.
5.3.1 Thermally uninsulated —
C.3.3 Installation inside the smoke reservoir —
C.3.3 Installation outside the smoke reservoir —
A.1 i) Horizontal direction of motor shaft —
A.1 i) Vertical direction of motor shaft —
A.1 n) Converter feed (driven by frequency —
converter)
A.1 n) Direct feed (no speed variation) —
C.4.2.1 Dual purpose use —
C.4.2.1, C.4.2.2 Emergency only use —
C.3.3 Ducted cooling air required —
4.2.3 Motor rating
Since the PSHC ventilator (fan) can be operated at different temperatures (current or emergency),
motors shall be selected for operation at the power required for normal ambient temperature and not
just for operation at high temperature.
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ISO 21927-3:2021(E)

Selection of the motors shall conform with the following requirements:
— Motors shall conform with the requirements of IEC 60034-1.
— Motor ratings shall be limited by the temperature rise for one class lower than the insulation class
of the motor, as defined in IEC 60085.
— The fan tested in accordance with 5.3.2 shall conform with the stability requirement in C.4.2.2.
4.3 Effectiveness of smoke/hot gas extraction
4.3.1 General
The effectiveness of smoke/hot gas extraction of the fan is the ability to continue to extract the required
volume flow at high temperature.
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test
The effectiveness of smoke/hot gas extraction is demonstrated by conformance with the performance
requirements in C.5, when tested according to 5.4.
4.4 Resistance to fire
The fan is shown to be functioning satisfactorily by its continued ability to provide the initial volume or
pressure within the defined limits in C.5, when tested according to 5.5.
The test result shall be classified in accordance with EN 13501-4.
4.5 Ability to open under environmental conditions
4.5.1 Opening under wind load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.5.2 Opening under snow load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.6 Durability of operational reliability
Durability of operational reliability is demonstrated by motor rating according to 4.2.3 when tested
according to 5.7.
5 Testing, assessment and sampling methods
5.1 General
PSHC ventilator (fan), tests shall be carried out in accordance with Annexes A, B, C and E.
For each test, a test report shall be prepared in accordance with Annex C.
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ISO 21927-3:2021(E)

A fan can be tested completely assembled with ancillaries, for example:
— flexible connection elements;
— anchors (fastenings for mounting to external structure);
— airflow operated dampers or external powered dampers;
— shock absorber (anti-vibration mount);
— sound absorber (silencer or acoustic attenuator);
— support construction (e.g. for powered roof or partition fans);
— thermal protection (e.g. PTC thermistor, Thermocouple, Pt100, etc.);
— ON-OFF switch and other electrical ancillaries (e.g. electrical safety box) which are directly mounted
on the fan;
— guide vanes;
— flow deflectors;
— a jet fan shall be tested completely assembled and suspended from a supporting construction in
accordance with the manufacturer’s installation instructions.
For testing of motors alone, tests shall be carried out and test reports prepared in accordance with
Annex D.
5.2 Test of response delay (response time) opening under wind / snow load within
a given time
5.2.1 Wind load
The fan shutter, flaps or louvers shall open in less than 30 s against a horizontally applied load of 200 Pa,
simulated by means of an additional fan blowing on the flap at a suitable velocity, or by any suitable
mechanical means when the fan is tested in accordance with Annex E and/or Annex C.
WARNING — For fans which use the air pressure from the fan to open flaps or louvers.
Due to the temperature rise, the density of air decreases resulting in a corresponding decrease
in the pressure developed. This pressure is needed to open the termination system (flaps or
louvers).
In this case, the laboratory shall perform the wind load test also during the high temperature
test.
If fans selected according to Annex A and tested according to Annex C are intended for use with
external, air-pressure operated shutters, the combination shall also be tested with a wind load
according to Annex E.
The operating position can be considered as reached if the volume flow exhausted by the fan
working under wind loads did not decrease by more than 10 % of that exhausted by the fan
working without these loads.
If a fan intended for mounting on an external wall is fitted with external shutters, flaps or
louvers and/or is not protected from wind force acting against it by a deflector or cowl, it shall
be tested in accordance with this Clause. Otherwise, the manufacture shall include a statement
in his instructions that suitable wind guarding shall be fitted by the installer.
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ISO 21927-3:2021(E)

5.2.2 Snow load
The fan shutter, flaps or louvers shall open in less than 30 s against a vertically applied load shown
in Table 2, simulated by any suitable mechanical means, when the fan is tested in accordance with
Annex E, at ambient temperature only.
Table 2 — Snow load classes
Class Load
Pa
SL 0 0
SL 125 125
SL 250 250
SL 500 500
SL 1 000 1 000
SL A A
The operating position can be considered as reached if the volume flow exhausted by the fan working
under snow loads did not decrease by more than 10 % of that exhausted by the fan working without
these loads.
Where the minimum angle of installation recommended by the supplier exceeds 45° from the
horizontal, the fan takes the classification SL 1 000 without a test, except where snow is prevented from
slipping from the fan, for example by wind deflectors. In this case, the fan shall be tested for a snow load
classification which shall not be less than SL = 2 000 · d, where d is the depth of snow, in metres, which
can be contained with the confines of the deflectors.
5.3 Operational reliability
5.3.1 Application categories
The relevant test methods are those indicated in Table 1 in 4.2.2.
5.3.2 Motor rating
The test method to be applied is in C.4.2.
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test
The test method is given in Annex C.
5.5 Resistance to fire
The test method is given in Annex C.
5.6 Ability to open under environmental conditions: opening under wind or snow load
within a given time
The test method is given in Annex E.
5.7 Durability of operational reliability
Durability of operational reliability is demonstrated by the test method given in 5.3.2.
6 © ISO 2021 – All rights reserved

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ISO 21927-3:2021(E)

6 Marking, labelling and packaging
The PSHC ventilator (fan) shall be marked with the following:
— the manufacturer’s name or trademark;
— the resistance to fire classification;
— a reference to this document and its year of its publication (i.e. ISO 21927-3:2021, followed by the
generic name of the product "powered smoke and heat control ventilator";
— the model/type;
— power requirements, e.g. power, current, voltage and rotational speed;
— the snow load class where applicable;
— the flow direction inside the fan (motor upstream, downstream or both);
— the direction of the motor shaft (vertical, horizontal or both);
— the minimum flow and maximum temperature of cooling air, where applicable;
— information about electrical connections of motor (e.g. Y or Δ);
— the following statement: "This powered smoke and heat control ventilator shall be installed as per
the manufacturer's instructions.";
— the manufacturer's installation instructions or a reference to a document held by the manufacturer
giving these instructions;
— the date of manufacture (month and year).
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ISO 21927-3:2021(E)

Annex A
(normative)

Criteria to determine the family of fans in order to select the sizes
to be tested
A.1 Reduction of numbers of tests for PSHC ventilators forming a product range
It is not usually considered necessary to test every size of ventilator in a family of fans, provided that
the following are tested and the family conforms to the rules given in A.3, A.4 and Annex B:
a) the fan with the most highly stressed impeller, and the ventilators with impellers in which the
individual stress in any component, weld or fastening is the highest, as appropriate, if not the same
(see A.4);
b) for fans with motors mounted in an enclosure which restricts the cooling, the worst case shall be
tested; this is the smallest free area of the motor enclosure or the smallest section of exit or entry
airway for cooling air;
c) at least two sizes of fans are tested at their highest rotational speed;
d) the fan with the smallest motor frame size to be used, except for fans where the impeller is not
mounted on the motor shaft and the motors are out of the airstream in ambient air and the cooling
of the motor is not affected by heat transfer from the ventilator or the ventilator construction;
e) if the highest impeller stress levels are determined by geometric similarity conditions from A.4.1,
sufficient sizes of fans to ensure that the impeller diameters of the range are from 0,8 to 1,27 of
those tested;
f) if the highest impeller stress levels are determined by the calculation methods in A.4.2, sufficient
sizes of fans to ensure that the impeller diameters of the range are from 0,63 to 1,27 of those tested;
NOTE The coefficients are taken from Renard Series R20 in accordance with several ISO standards. The
aim of the coefficients 0,8 or 0,63 and 1,27 is to validate fans down to 2 or 4 sizes smaller and up to 2 sizes
larger than the tested size. See Annex F for more information.
g) for a direct drive axial fan where the blade profile i
...

INTERNATIONAL ISO
STANDARD 21927-3
Second edition
2021-05
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and
heat exhaust ventilators
Systèmes de contrôle de fumée et de chaleur —
Partie 3: Spécifications pour les ventilateurs mécaniques d'évacuation
des fumées et de la chaleur
Reference number
ISO 21927-3:2021(E)
©
ISO 2021

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ISO 21927-3:2021(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
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 2021 – All rights reserved

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ISO 21927-3:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
4 Requirements . 2
4.1 Response delay (response time) . 2
4.1.1 Opening under wind load within a given time . 2
4.1.2 Opening under snow load within a given time . 3
4.2 Operational reliability . 3
4.2.1 General. 3
4.2.2 Application categories . 3
4.2.3 Motor rating . 3
4.3 Effectiveness of smoke/hot gas extraction . 4
4.3.1 General. 4
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test . 4
4.4 Resistance to fire . 4
4.5 Ability to open under environmental conditions . 4
4.5.1 Opening under wind load within a given time . 4
4.5.2 Opening under snow load within a given time . 4
4.6 Durability of operational reliability . 4
5 Testing, assessment and sampling methods. 4
5.1 General . 4
5.2 Test of response delay (response time) opening under wind / snow load within
a given time . 5
5.2.1 Wind load . 5
5.2.2 Snow load . 6
5.3 Operational reliability . 6
5.3.1 Application categories . 6
5.3.2 Motor rating . 6
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test . 6
5.5 Resistance to fire . 6
5.6 Ability to open under environmental conditions: opening under wind or snow
load within a given time . 6
5.7 Durability of operational reliability . 6
6 Marking, labelling and packaging . 7
Annex A (normative) Criteria to determine the family of fans in order to select the sizes
to be tested. 8
Annex B (normative) Criteria to determine a family of motors in order to select the sizes
to be tested.29
Annex C (normative) Test method for the determination of fire resistance of powered
smoke and heat control ventilators (fans) .38
Annex D (normative) Test methods for electric motors to determine the impact of
the changes on the product characteristics .47
Annex E (normative) Test method for assessing the response delay and ability to open
under environmental conditions .52
Annex F (informative) Explanatory notes .53
Annex G (informative) General guidance for installation and maintenance .69
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ISO 21927-3:2021(E)

Bibliography .70
iv © ISO 2021 – All rights reserved

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ISO 21927-3:2021(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 21, Equipment for fire protection and fire
fighting, Subcommittee SC 11, Smoke and heat control systems and components.
This second edition cancels and replaces the first edition (ISO 21927-3:2006), which has been technically
revised. It also incorporates the Amendment ISO 21927-3:2006/Amd. 1:2010.
The main changes compared to the previous edition are as follows:
— amendment of the test apparatus;
A list of all parts in the ISO 21927 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.
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ISO 21927-3:2021(E)

Introduction
Smoke and heat exhaust ventilation systems create a smoke-free layer above the floor by removing
smoke and, thus, improve the conditions for the safe escape and/or rescue of people and animals and
the protection of property and permit the fire to be fought while still in its early stages. They also
exhaust hot gases released by a fire in the developing stage.
The use of smoke and heat exhaust ventilation systems to create smoke-free areas beneath a buoyant
smoke layer has become widespread. Their value in assisting in the evacuation of people from
construction works, reducing fire damage and financial loss by preventing smoke logging, facilitating
firefighting, reducing roof temperatures and delaying the lateral spread of fire is firmly established.
For these benefits to be obtained, it is essential that smoke and heat exhaust ventilation systems be a
scheme of safety equipment intended to perform a positive role in a fire emergency.
vi © ISO 2021 – All rights reserved

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INTERNATIONAL STANDARD ISO 21927-3:2021(E)
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and heat exhaust
ventilators
1 Scope
This document specifies the product characteristics for powered smoke and heat control ventilators
(fans) intended to be used as part of a powered smoke and heat control ventilation system in
construction works.
It provides test and assessment methods of the characteristics and the conformance criteria of the test
assessment results.
This document applies to the following:
a) fans for smoke and heat control ventilation;
b) impulse/jet fans for smoke and heat control ventilation.
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 281, Rolling bearings — Dynamic load ratings and rating life
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5801, Fans — Performance testing using standardized airways
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60034-2-1, Rotating electrical machines — Part 2-1: Standard methods for determining losses and
efficiency from tests (excluding machines for traction vehicles)
IEC 60085, Electrical insulation — Thermal evaluation and designation
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
EN 1363-1, Fire resistance tests — Part 1: General Requirements
EN 13501-4, Fire classification of construction products and building elements — Part 4: Classification
using data from fire resistance tests on components of smoke control systems
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
© ISO 2021 – All rights reserved 1

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ISO 21927-3:2021(E)

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 http:// www .electropedia .org/
3.1
powered smoke and heat control ventilator
PSHC ventilator
smoke-ventilating fan that is suitable for handling smoke and hot gases for a specified time/temperature
profile
3.2
smoke reservoir
region within a building, limited or bordered by smoke curtains or structural elements, which retains a
thermally buoyant smoke layer in the event of a fire
3.3
powered roof ventilator
fan designed for mounting on a roof and with exterior weather protection
3.4
smoke reservoir ventilator
ventilator suitable for operation fully immersed in a smoke reservoir (3.2)
3.5
product family
physically similar fans using the same form of construction and materials throughout, with the same
methods of impeller construction, motor mounting and construction, and electrical connection in which
the following may vary across the range:
— overall dimensions of the fans; and/or
— the impeller diameter and width, hub size, blade length and number of blades of the impeller; and/
or
— the motor details, as per 3.7
3.6
impulse/jet fans for smoke and heat control ventilation
fan used for producing a jet of air in a space and unconnected to any ducting
Note 1 to entry: The air jet may be used, for example, for adding momentum to the air within a duct, a tunnel or
other space, or for intensifying the heat transfer in a determined zone.
3.7
motor rating
maximum power that a motor delivers continuously without exceeding the allowable temperature rise
4 Requirements
4.1 Response delay (response time)
4.1.1 Opening under wind load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.1.
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ISO 21927-3:2021(E)

4.1.2 Opening under snow load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.2.
4.2 Operational reliability
4.2.1 General
Operational reliability of a PSHC ventilator (fan) shall be demonstrated by verification against
application categories and by verification of motor ratings.
4.2.2 Application categories
To demonstrate its operational reliability, a PSHC ventilator (fan) shall be verified against certain
categories.
Table 1 shows the relevant method to allocate the results in the corresponding category.
Table 1 — Application categories
Subclause of the test
method (within ISO Application category Conformance criteria
21927-3)
5.3.1 Thermally insulated When tested in accordance with
Annex C:
— the outer surface temperature of
a thermal insulated fan shall not
increase by more than 180 K for any
individual value;
— the cooling air expelled from the
unit shall not exhibit an increase
of temperature of more than 180 K
from the initial room temperature.
5.3.1 Thermally uninsulated —
C.3.3 Installation inside the smoke reservoir —
C.3.3 Installation outside the smoke reservoir —
A.1 i) Horizontal direction of motor shaft —
A.1 i) Vertical direction of motor shaft —
A.1 n) Converter feed (driven by frequency —
converter)
A.1 n) Direct feed (no speed variation) —
C.4.2.1 Dual purpose use —
C.4.2.1, C.4.2.2 Emergency only use —
C.3.3 Ducted cooling air required —
4.2.3 Motor rating
Since the PSHC ventilator (fan) can be operated at different temperatures (current or emergency),
motors shall be selected for operation at the power required for normal ambient temperature and not
just for operation at high temperature.
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ISO 21927-3:2021(E)

Selection of the motors shall conform with the following requirements:
— Motors shall conform with the requirements of IEC 60034-1.
— Motor ratings shall be limited by the temperature rise for one class lower than the insulation class
of the motor, as defined in IEC 60085.
— The fan tested in accordance with 5.3.2 shall conform with the stability requirement in C.4.2.2.
4.3 Effectiveness of smoke/hot gas extraction
4.3.1 General
The effectiveness of smoke/hot gas extraction of the fan is the ability to continue to extract the required
volume flow at high temperature.
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test
The effectiveness of smoke/hot gas extraction is demonstrated by conformance with the performance
requirements in C.5, when tested according to 5.4.
4.4 Resistance to fire
The fan is shown to be functioning satisfactorily by its continued ability to provide the initial volume or
pressure within the defined limits in C.5, when tested according to 5.5.
The test result shall be classified in accordance with EN 13501-4.
4.5 Ability to open under environmental conditions
4.5.1 Opening under wind load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.5.2 Opening under snow load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.6 Durability of operational reliability
Durability of operational reliability is demonstrated by motor rating according to 4.2.3 when tested
according to 5.7.
5 Testing, assessment and sampling methods
5.1 General
PSHC ventilator (fan), tests shall be carried out in accordance with Annexes A, B, C and E.
For each test, a test report shall be prepared in accordance with Annex C.
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ISO 21927-3:2021(E)

A fan can be tested completely assembled with ancillaries, for example:
— flexible connection elements;
— anchors (fastenings for mounting to external structure);
— airflow operated dampers or external powered dampers;
— shock absorber (anti-vibration mount);
— sound absorber (silencer or acoustic attenuator);
— support construction (e.g. for powered roof or partition fans);
— thermal protection (e.g. PTC thermistor, Thermocouple, Pt100, etc.);
— ON-OFF switch and other electrical ancillaries (e.g. electrical safety box) which are directly mounted
on the fan;
— guide vanes;
— flow deflectors;
— a jet fan shall be tested completely assembled and suspended from a supporting construction in
accordance with the manufacturer’s installation instructions.
For testing of motors alone, tests shall be carried out and test reports prepared in accordance with
Annex D.
5.2 Test of response delay (response time) opening under wind / snow load within
a given time
5.2.1 Wind load
The fan shutter, flaps or louvers shall open in less than 30 s against a horizontally applied load of 200 Pa,
simulated by means of an additional fan blowing on the flap at a suitable velocity, or by any suitable
mechanical means when the fan is tested in accordance with Annex E and/or Annex C.
WARNING — For fans which use the air pressure from the fan to open flaps or louvers.
Due to the temperature rise, the density of air decreases resulting in a corresponding decrease
in the pressure developed. This pressure is needed to open the termination system (flaps or
louvers).
In this case, the laboratory shall perform the wind load test also during the high temperature
test.
If fans selected according to Annex A and tested according to Annex C are intended for use with
external, air-pressure operated shutters, the combination shall also be tested with a wind load
according to Annex E.
The operating position can be considered as reached if the volume flow exhausted by the fan
working under wind loads did not decrease by more than 10 % of that exhausted by the fan
working without these loads.
If a fan intended for mounting on an external wall is fitted with external shutters, flaps or
louvers and/or is not protected from wind force acting against it by a deflector or cowl, it shall
be tested in accordance with this Clause. Otherwise, the manufacture shall include a statement
in his instructions that suitable wind guarding shall be fitted by the installer.
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ISO 21927-3:2021(E)

5.2.2 Snow load
The fan shutter, flaps or louvers shall open in less than 30 s against a vertically applied load shown
in Table 2, simulated by any suitable mechanical means, when the fan is tested in accordance with
Annex E, at ambient temperature only.
Table 2 — Snow load classes
Class Load
Pa
SL 0 0
SL 125 125
SL 250 250
SL 500 500
SL 1 000 1 000
SL A A
The operating position can be considered as reached if the volume flow exhausted by the fan working
under snow loads did not decrease by more than 10 % of that exhausted by the fan working without
these loads.
Where the minimum angle of installation recommended by the supplier exceeds 45° from the
horizontal, the fan takes the classification SL 1 000 without a test, except where snow is prevented from
slipping from the fan, for example by wind deflectors. In this case, the fan shall be tested for a snow load
classification which shall not be less than SL = 2 000 · d, where d is the depth of snow, in metres, which
can be contained with the confines of the deflectors.
5.3 Operational reliability
5.3.1 Application categories
The relevant test methods are those indicated in Table 1 in 4.2.2.
5.3.2 Motor rating
The test method to be applied is in C.4.2.
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test
The test method is given in Annex C.
5.5 Resistance to fire
The test method is given in Annex C.
5.6 Ability to open under environmental conditions: opening under wind or snow load
within a given time
The test method is given in Annex E.
5.7 Durability of operational reliability
Durability of operational reliability is demonstrated by the test method given in 5.3.2.
6 © ISO 2021 – All rights reserved

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ISO 21927-3:2021(E)

6 Marking, labelling and packaging
The PSHC ventilator (fan) shall be marked with the following:
— the manufacturer’s name or trademark;
— the resistance to fire classification;
— a reference to this document and its year of its publication (i.e. ISO 21927-3:2021, followed by the
generic name of the product "powered smoke and heat control ventilator";
— the model/type;
— power requirements, e.g. power, current, voltage and rotational speed;
— the snow load class where applicable;
— the flow direction inside the fan (motor upstream, downstream or both);
— the direction of the motor shaft (vertical, horizontal or both);
— the minimum flow and maximum temperature of cooling air, where applicable;
— information about electrical connections of motor (e.g. Y or Δ);
— the following statement: "This powered smoke and heat control ventilator shall be installed as per
the manufacturer's instructions.";
— the manufacturer's installation instructions or a reference to a document held by the manufacturer
giving these instructions;
— the date of manufacture (month and year).
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ISO 21927-3:2021(E)

Annex A
(normative)

Criteria to determine the family of fans in order to select the sizes
to be tested
A.1 Reduction of numbers of tests for PSHC ventilators forming a product range
It is not usually considered necessary to test every size of ventilator in a family of fans, provided that
the following are tested and the family conforms to the rules given in A.3, A.4 and Annex B:
a) the fan with the most highly stressed impeller, and the ventilators with impellers in which the
individual stress in any component, weld or fastening is the highest, as appropriate, if not the same
(see A.4);
b) for fans with motors mounted in an enclosure which restricts the cooling, the worst case shall be
tested; this is the smallest free area of the motor enclosure or the smallest section of exit or entry
airway for cooling air;
c) at least two sizes of fans are tested at their highest rotational speed;
d) the fan with the smallest motor frame size to be used, except for fans where the impeller is not
mounted on the motor shaft and the motors are out of the airstream in ambient air and the cooling
of the motor is not affected by heat transfer from the ventilator or the ventilator construction;
e) if the highest impeller stress levels are determined by geometric similarity conditions from A.4.1,
sufficient sizes of fans to ensure that the impeller diameters of the range are from 0,8 to 1,27 of
those tested;
f) if the highest impeller stress levels are determined by the calculation methods in A.4.2, sufficient
sizes of fans to ensure that the impeller diameters of the range are from 0,63 to 1,27 of those tested;
NOTE The coefficients are taken from Renard Series R20 in accordance with several ISO standards. The
aim of the coefficients 0,8 or 0,63 and 1,27 is to validate fans down to 2 or 4 sizes smaller and up to 2 sizes
larger than the tested size. See Annex F for more information.
g) for a direct drive axial fan where the blade profile i
...

INTERNATIONAL ISO
STANDARD 21927-3
Second edition
2021-05
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and
heat exhaust ventilators
Systèmes de contrôle de fumée et de chaleur —
Partie 3: Spécifications pour les ventilateurs mécaniques d'évacuation
des fumées et de la chaleur
Reference number
ISO 21927-3:2021(E)
©
ISO 2021

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ISO 21927-3:2021(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
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 2021 – All rights reserved

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ISO 21927-3:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
4 Requirements . 2
4.1 Response delay (response time) . 2
4.1.1 Opening under wind load within a given time . 2
4.1.2 Opening under snow load within a given time . 3
4.2 Operational reliability . 3
4.2.1 General. 3
4.2.2 Application categories . 3
4.2.3 Motor rating . 3
4.3 Effectiveness of smoke/hot gas extraction . 4
4.3.1 General. 4
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test . 4
4.4 Resistance to fire . 4
4.5 Ability to open under environmental conditions . 4
4.5.1 Opening under wind load within a given time . 4
4.5.2 Opening under snow load within a given time . 4
4.6 Durability of operational reliability . 4
5 Testing, assessment and sampling methods. 4
5.1 General . 4
5.2 Test of response delay (response time) opening under wind / snow load within
a given time . 5
5.2.1 Wind load . 5
5.2.2 Snow load . 6
5.3 Operational reliability . 6
5.3.1 Application categories . 6
5.3.2 Motor rating . 6
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test . 6
5.5 Resistance to fire . 6
5.6 Ability to open under environmental conditions: opening under wind or snow
load within a given time . 6
5.7 Durability of operational reliability . 6
6 Marking, labelling and packaging . 7
Annex A (normative) Criteria to determine the family of fans in order to select the sizes
to be tested. 8
Annex B (normative) Criteria to determine a family of motors in order to select the sizes
to be tested.29
Annex C (normative) Test method for the determination of fire resistance of powered
smoke and heat control ventilators (fans) .38
Annex D (normative) Test methods for electric motors to determine the impact of
the changes on the product characteristics .47
Annex E (normative) Test method for assessing the response delay and ability to open
under environmental conditions .52
Annex F (informative) Explanatory notes .53
Annex G (informative) General guidance for installation and maintenance .69
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ISO 21927-3:2021(E)

Bibliography .70
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ISO 21927-3:2021(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 21, Equipment for fire protection and fire
fighting, Subcommittee SC 11, Smoke and heat control systems and components.
This second edition cancels and replaces the first edition (ISO 21927-3:2006), which has been technically
revised. It also incorporates the Amendment ISO 21927-3:2006/Amd. 1:2010.
The main changes compared to the previous edition are as follows:
— amendment of the test apparatus;
A list of all parts in the ISO 21927 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.
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ISO 21927-3:2021(E)

Introduction
Smoke and heat exhaust ventilation systems create a smoke-free layer above the floor by removing
smoke and, thus, improve the conditions for the safe escape and/or rescue of people and animals and
the protection of property and permit the fire to be fought while still in its early stages. They also
exhaust hot gases released by a fire in the developing stage.
The use of smoke and heat exhaust ventilation systems to create smoke-free areas beneath a buoyant
smoke layer has become widespread. Their value in assisting in the evacuation of people from
construction works, reducing fire damage and financial loss by preventing smoke logging, facilitating
firefighting, reducing roof temperatures and delaying the lateral spread of fire is firmly established.
For these benefits to be obtained, it is essential that smoke and heat exhaust ventilation systems be a
scheme of safety equipment intended to perform a positive role in a fire emergency.
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INTERNATIONAL STANDARD ISO 21927-3:2021(E)
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and heat exhaust
ventilators
1 Scope
This document specifies the product characteristics for powered smoke and heat control ventilators
(fans) intended to be used as part of a powered smoke and heat control ventilation system in
construction works.
It provides test and assessment methods of the characteristics and the conformance criteria of the test
assessment results.
This document applies to the following:
a) fans for smoke and heat control ventilation;
b) impulse/jet fans for smoke and heat control ventilation.
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 281, Rolling bearings — Dynamic load ratings and rating life
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5801, Fans — Performance testing using standardized airways
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60034-2-1, Rotating electrical machines — Part 2-1: Standard methods for determining losses and
efficiency from tests (excluding machines for traction vehicles)
IEC 60085, Electrical insulation — Thermal evaluation and designation
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
EN 1363-1, Fire resistance tests — Part 1: General Requirements
EN 13501-4, Fire classification of construction products and building elements — Part 4: Classification
using data from fire resistance tests on components of smoke control systems
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
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ISO 21927-3:2021(E)

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 http:// www .electropedia .org/
3.1
powered smoke and heat control ventilator
PSHC ventilator
smoke-ventilating fan that is suitable for handling smoke and hot gases for a specified time/temperature
profile
3.2
smoke reservoir
region within a building, limited or bordered by smoke curtains or structural elements, which retains a
thermally buoyant smoke layer in the event of a fire
3.3
powered roof ventilator
fan designed for mounting on a roof and with exterior weather protection
3.4
smoke reservoir ventilator
ventilator suitable for operation fully immersed in a smoke reservoir (3.2)
3.5
product family
physically similar fans using the same form of construction and materials throughout, with the same
methods of impeller construction, motor mounting and construction, and electrical connection in which
the following may vary across the range:
— overall dimensions of the fans; and/or
— the impeller diameter and width, hub size, blade length and number of blades of the impeller; and/
or
— the motor details, as per 3.7
3.6
impulse/jet fans for smoke and heat control ventilation
fan used for producing a jet of air in a space and unconnected to any ducting
Note 1 to entry: The air jet may be used, for example, for adding momentum to the air within a duct, a tunnel or
other space, or for intensifying the heat transfer in a determined zone.
3.7
motor rating
maximum power that a motor delivers continuously without exceeding the allowable temperature rise
4 Requirements
4.1 Response delay (response time)
4.1.1 Opening under wind load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.1.
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ISO 21927-3:2021(E)

4.1.2 Opening under snow load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.2.
4.2 Operational reliability
4.2.1 General
Operational reliability of a PSHC ventilator (fan) shall be demonstrated by verification against
application categories and by verification of motor ratings.
4.2.2 Application categories
To demonstrate its operational reliability, a PSHC ventilator (fan) shall be verified against certain
categories.
Table 1 shows the relevant method to allocate the results in the corresponding category.
Table 1 — Application categories
Subclause of the test
method (within ISO Application category Conformance criteria
21927-3)
5.3.1 Thermally insulated When tested in accordance with
Annex C:
— the outer surface temperature of
a thermal insulated fan shall not
increase by more than 180 K for any
individual value;
— the cooling air expelled from the
unit shall not exhibit an increase
of temperature of more than 180 K
from the initial room temperature.
5.3.1 Thermally uninsulated —
C.3.3 Installation inside the smoke reservoir —
C.3.3 Installation outside the smoke reservoir —
A.1 i) Horizontal direction of motor shaft —
A.1 i) Vertical direction of motor shaft —
A.1 n) Converter feed (driven by frequency —
converter)
A.1 n) Direct feed (no speed variation) —
C.4.2.1 Dual purpose use —
C.4.2.1, C.4.2.2 Emergency only use —
C.3.3 Ducted cooling air required —
4.2.3 Motor rating
Since the PSHC ventilator (fan) can be operated at different temperatures (current or emergency),
motors shall be selected for operation at the power required for normal ambient temperature and not
just for operation at high temperature.
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ISO 21927-3:2021(E)

Selection of the motors shall conform with the following requirements:
— Motors shall conform with the requirements of IEC 60034-1.
— Motor ratings shall be limited by the temperature rise for one class lower than the insulation class
of the motor, as defined in IEC 60085.
— The fan tested in accordance with 5.3.2 shall conform with the stability requirement in C.4.2.2.
4.3 Effectiveness of smoke/hot gas extraction
4.3.1 General
The effectiveness of smoke/hot gas extraction of the fan is the ability to continue to extract the required
volume flow at high temperature.
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test
The effectiveness of smoke/hot gas extraction is demonstrated by conformance with the performance
requirements in C.5, when tested according to 5.4.
4.4 Resistance to fire
The fan is shown to be functioning satisfactorily by its continued ability to provide the initial volume or
pressure within the defined limits in C.5, when tested according to 5.5.
The test result shall be classified in accordance with EN 13501-4.
4.5 Ability to open under environmental conditions
4.5.1 Opening under wind load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.5.2 Opening under snow load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with
5.6.
4.6 Durability of operational reliability
Durability of operational reliability is demonstrated by motor rating according to 4.2.3 when tested
according to 5.7.
5 Testing, assessment and sampling methods
5.1 General
PSHC ventilator (fan), tests shall be carried out in accordance with Annexes A, B, C and E.
For each test, a test report shall be prepared in accordance with Annex C.
4 © ISO 2021 – All rights reserved

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ISO 21927-3:2021(E)

A fan can be tested completely assembled with ancillaries, for example:
— flexible connection elements;
— anchors (fastenings for mounting to external structure);
— airflow operated dampers or external powered dampers;
— shock absorber (anti-vibration mount);
— sound absorber (silencer or acoustic attenuator);
— support construction (e.g. for powered roof or partition fans);
— thermal protection (e.g. PTC thermistor, Thermocouple, Pt100, etc.);
— ON-OFF switch and other electrical ancillaries (e.g. electrical safety box) which are directly mounted
on the fan;
— guide vanes;
— flow deflectors;
— a jet fan shall be tested completely assembled and suspended from a supporting construction in
accordance with the manufacturer’s installation instructions.
For testing of motors alone, tests shall be carried out and test reports prepared in accordance with
Annex D.
5.2 Test of response delay (response time) opening under wind / snow load within
a given time
5.2.1 Wind load
The fan shutter, flaps or louvers shall open in less than 30 s against a horizontally applied load of 200 Pa,
simulated by means of an additional fan blowing on the flap at a suitable velocity, or by any suitable
mechanical means when the fan is tested in accordance with Annex E and/or Annex C.
WARNING — For fans which use the air pressure from the fan to open flaps or louvers.
Due to the temperature rise, the density of air decreases resulting in a corresponding decrease
in the pressure developed. This pressure is needed to open the termination system (flaps or
louvers).
In this case, the laboratory shall perform the wind load test also during the high temperature
test.
If fans selected according to Annex A and tested according to Annex C are intended for use with
external, air-pressure operated shutters, the combination shall also be tested with a wind load
according to Annex E.
The operating position can be considered as reached if the volume flow exhausted by the fan
working under wind loads did not decrease by more than 10 % of that exhausted by the fan
working without these loads.
If a fan intended for mounting on an external wall is fitted with external shutters, flaps or
louvers and/or is not protected from wind force acting against it by a deflector or cowl, it shall
be tested in accordance with this Clause. Otherwise, the manufacture shall include a statement
in his instructions that suitable wind guarding shall be fitted by the installer.
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ISO 21927-3:2021(E)

5.2.2 Snow load
The fan shutter, flaps or louvers shall open in less than 30 s against a vertically applied load shown
in Table 2, simulated by any suitable mechanical means, when the fan is tested in accordance with
Annex E, at ambient temperature only.
Table 2 — Snow load classes
Class Load
Pa
SL 0 0
SL 125 125
SL 250 250
SL 500 500
SL 1 000 1 000
SL A A
The operating position can be considered as reached if the volume flow exhausted by the fan working
under snow loads did not decrease by more than 10 % of that exhausted by the fan working without
these loads.
Where the minimum angle of installation recommended by the supplier exceeds 45° from the
horizontal, the fan takes the classification SL 1 000 without a test, except where snow is prevented from
slipping from the fan, for example by wind deflectors. In this case, the fan shall be tested for a snow load
classification which shall not be less than SL = 2 000 · d, where d is the depth of snow, in metres, which
can be contained with the confines of the deflectors.
5.3 Operational reliability
5.3.1 Application categories
The relevant test methods are those indicated in Table 1 in 4.2.2.
5.3.2 Motor rating
The test method to be applied is in C.4.2.
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test
The test method is given in Annex C.
5.5 Resistance to fire
The test method is given in Annex C.
5.6 Ability to open under environmental conditions: opening under wind or snow load
within a given time
The test method is given in Annex E.
5.7 Durability of operational reliability
Durability of operational reliability is demonstrated by the test method given in 5.3.2.
6 © ISO 2021 – All rights reserved

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ISO 21927-3:2021(E)

6 Marking, labelling and packaging
The PSHC ventilator (fan) shall be marked with the following:
— the manufacturer’s name or trademark;
— the resistance to fire classification;
— a reference to this document and its year of its publication (i.e. ISO 21927-3:2021, followed by the
generic name of the product "powered smoke and heat control ventilator";
— the model/type;
— power requirements, e.g. power, current, voltage and rotational speed;
— the snow load class where applicable;
— the flow direction inside the fan (motor upstream, downstream or both);
— the direction of the motor shaft (vertical, horizontal or both);
— the minimum flow and maximum temperature of cooling air, where applicable;
— information about electrical connections of motor (e.g. Y or Δ);
— the following statement: "This powered smoke and heat control ventilator shall be installed as per
the manufacturer's instructions.";
— the manufacturer's installation instructions or a reference to a document held by the manufacturer
giving these instructions;
— the date of manufacture (month and year).
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ISO 21927-3:2021(E)

Annex A
(normative)

Criteria to determine the family of fans in order to select the sizes
to be tested
A.1 Reduction of numbers of tests for PSHC ventilators forming a product range
It is not usually considered necessary to test every size of ventilator in a family of fans, provided that
the following are tested and the family conforms to the rules given in A.3, A.4 and Annex B:
a) the fan with the most highly stressed impeller, and the ventilators with impellers in which the
individual stress in any component, weld or fastening is the highest, as appropriate, if not the same
(see A.4);
b) for fans with motors mounted in an enclosure which restricts the cooling, the worst case shall be
tested; this is the smallest free area of the motor enclosure or the smallest section of exit or entry
airway for cooling air;
c) at least two sizes of fans are tested at their highest rotational speed;
d) the fan with the smallest motor frame size to be used, except for fans where the impeller is not
mounted on the motor shaft and the motors are out of the airstream in ambient air and the cooling
of the motor is not affected by heat transfer from the ventilator or the ventilator construction;
e) if the highest impeller stress levels are determined by geometric similarity conditions from A.4.1,
sufficient sizes of fans to ensure that the impeller diameters of the range are from 0,8 to 1,27 of
those tested;
f) if the highest impeller stress levels are determined by the calculation methods in A.4.2, sufficient
sizes of fans to ensure that the impeller diameters of the range are from 0,63 to 1,27 of those tested;
NOTE The coefficients are taken from Renard Series R20 in accordance with several ISO standards. The
aim of the coefficients 0,8 or 0,63 and 1,27 is to validate fans down to 2 or 4 sizes smaller and up to 2 sizes
larger than the tested size. See Annex F for more information.
g) for a direct drive axial fan where the blade profile i
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21927-3.2
ISO/TC 21/SC 11
Smoke and heat control systems —
Secretariat: DIN
Voting begins on:
Part 3:
2021-02-02
Specifications for powered smoke and
Voting terminates on:
heat exhaust ventilators
2021-04-02
Systèmes de contrôle de fumée et de chaleur —
Partie 3: Spécifications pour les ventilateurs mécaniques d'évacuation
des fumées et de la chaleur
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ISO/FDIS 21927-3.2:2021(E)
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©
NATIONAL REGULATIONS. ISO 2021

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ISO/FDIS 21927-3.2:2021(E)

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ISO/FDIS 21927-3.2:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
4 Requirements . 2
4.1 Response delay (response time) . 2
4.1.1 Opening under wind load within a given time . 2
4.1.2 Opening under snow load within a given time . 3
4.2 Operational reliability . 3
4.2.1 General. 3
4.2.2 Application categories . 3
4.2.3 Motor rating . 3
4.3 Effectiveness of smoke/hot gas extraction . 4
4.3.1 General. 4
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test . 4
4.4 Resistance to fire . 4
4.5 Ability to open under environmental conditions . 4
4.5.1 Opening under wind load within a given time . 4
4.5.2 Opening under snow load within a given time . 4
4.6 Durability of operational reliability . 4
5 Testing, assessment and sampling methods. 4
5.1 General . 4
5.2 Test of response delay (response time) opening under wind / snow load within
a given time . 5
5.2.1 Wind load . 5
5.2.2 Snow load . 5
5.3 Operational reliability . 6
5.3.1 Application categories . 6
5.3.2 Motor rating . 6
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test . 6
5.5 Resistance to fire . 6
5.6 Ability to open under environmental conditions: opening under wind or snow
load within a given time . 6
5.7 Durability of operational reliability . 6
6 Marking, labelling and packaging . 6
Annex A (normative) Criteria to determine the family of fans in order to select the sizes
to be tested. 8
Annex B (normative) Criteria to determine a family of motors in order to select the sizes
to be tested.29
Annex C (normative) Test method for the determination of fire resistance of powered
smoke and heat control ventilators (fans) .38
Annex D (normative) Test methods for electric motors to determine the impact of
the changes on the product characteristics .47
Annex E (normative) Test method for assessing the response delay and ability to open
under environmental conditions .52
Annex F (informative) Explanatory notes .53
Annex G (informative) General guidance for installation and maintenance .69
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ISO/FDIS 21927-3.2:2021(E)

Bibliography .70
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ISO/FDIS 21927-3.2:2021(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 21, Equipment for fire protection and fire
fighting, Subcommittee SC 11, Smoke and heat control systems and components.
This second edition cancels and replaces the first edition (ISO 21927-3:2006), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— amendment of the test apparatus;
A list of all parts in the ISO 21927 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.
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ISO/FDIS 21927-3.2:2021(E)

Introduction
Smoke and heat exhaust ventilation systems create a smoke-free layer above the floor by removing
smoke and, thus, improve the conditions for the safe escape and/or rescue of people and animals and
the protection of property and permit the fire to be fought while still in its early stages. They also
exhaust hot gases released by a fire in the developing stage.
The use of smoke and heat exhaust ventilation systems to create smoke-free areas beneath a buoyant
smoke layer has become widespread. Their value in assisting in the evacuation of people from
construction works, reducing fire damage and financial loss by preventing smoke logging, facilitating
firefighting, reducing roof temperatures and delaying the lateral spread of fire is firmly established.
For these benefits to be obtained, it is essential that smoke and heat exhaust ventilation systems be a
scheme of safety equipment intended to perform a positive role in a fire emergency.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21927-3.2:2021(E)
Smoke and heat control systems —
Part 3:
Specifications for powered smoke and heat exhaust
ventilators
1 Scope
This document specifies the product characteristics for powered smoke and heat control ventilators
(fans) intended to be used as part of a powered smoke and heat control ventilation system in
construction works.
It provides test and assessment methods of the characteristics and the conformance criteria of the test
assessment results.
This document applies to the following:
a) fans for smoke and heat control ventilation;
b) impulse/jet fans for smoke and heat control ventilation.
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 281, Rolling bearings — Dynamic load ratings and rating life
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5801, Fans — Performance testing using standardized airways
IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance
IEC 60034-2-1, Rotating electrical machines — Part 2-1: Standard methods for determining losses and
efficiency from tests (excluding machines for traction vehicles)
IEC 60085, Electrical insulation — Thermal evaluation and designation
IEC 60584-1, Thermocouples — Part 1: EMF specifications and tolerances
EN 1363-1, Fire resistance tests — Part 1: General Requirements
EN 13501-4, Fire classification of construction products and building elements — Part 4: Classification
using data from fire resistance tests on components of smoke control systems
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms and definitions apply.
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ISO/FDIS 21927-3.2:2021(E)

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 http:// www .electropedia .org/
3.1
powered smoke and heat control ventilator
PSHC ventilator
smoke-ventilating fan that is suitable for handling smoke and hot gases for a specified time/
temperature profile
3.2
smoke reservoir
region within a building, limited or bordered by smoke curtains or structural elements, which retains a
thermally buoyant smoke layer in the event of a fire
3.3
powered roof ventilator
fan designed for mounting on a roof and with exterior weather protection
3.4
smoke reservoir ventilator
ventilator suitable for operation fully immersed in a smoke reservoir (3.2)
3.5
product family
physically similar fans using the same form of construction and materials throughout, with the same
methods of impeller construction, motor mounting and construction, and electrical connection in which
the following may vary across the range:
— overall dimensions of the fans; and/or
— the impeller diameter and width, hub size, blade length and number of blades of the impeller; and/or
— the motor details, as per 3.7
3.6
impulse/jet fans for smoke and heat control ventilation
fan used for producing a jet of air in a space and unconnected to any ducting
Note 1 to entry: The air jet may be used, for example, for adding momentum to the air within a duct, a tunnel or
other space, or for intensifying the heat transfer in a determined zone.
3.7
motor rating
maximum power that a motor delivers continuously without exceeding the allowable temperature rise
4 Requirements
4.1 Response delay (response time)
4.1.1 Opening under wind load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.1.
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ISO/FDIS 21927-3.2:2021(E)

4.1.2 Opening under snow load within a given time
If the fan is designed to be installed at the atmospheric termination of a smoke control system
(e.g. powered roof ventilator) and is fitted with a fan shutter flaps or louvers which project above the
wind deflectors (cowl or wind shield), the shutter, flaps or louvers shall open in less than 30 s when
tested in accordance with 5.2.2.
4.2 Operational reliability
4.2.1 General
Operational reliability of a PSHC ventilator (fan) shall be demonstrated by verification against
application categories and by verification of motor ratings.
4.2.2 Application categories
To demonstrate its operational reliability, a PSHC ventilator (fan) shall be verified against certain
categories.
Table 1 shows the relevant method to allocate the results in the corresponding category.
Table 1 — Application categories
Subclause of the test
method (within ISO Application category Conformance criteria
21927-3)
5.3.1 Thermally insulated When tested in accordance with
Annex C:
— the outer surface temperature of
a thermal insulated fan shall not
increase by more than 180 K for any
individual value;
— the cooling air expelled from the
unit shall not exhibit an increase
of temperature of more than 180 K
from the initial room temperature.
5.3.1 Thermally uninsulated —
C.3.3 Installation inside the smoke reservoir —
C.3.3 Installation outside the smoke reservoir —
A.1 i) Horizontal direction of motor shaft —
A.1 i) Vertical direction of motor shaft —
A.1 n) Converter feed (driven by frequency —
converter)
A.1 n) Direct feed (no speed variation) —
C.4.2.1 Dual purpose use —
C.4.2.1, C.4.2.2 Emergency only use —
C.3.3 Ducted cooling air required —
4.2.3 Motor rating
Since the PSHC ventilator (fan) can be operated at different temperatures (current or emergency),
motors shall be selected for operation at the power required for normal ambient temperature and not
just for operation at high temperature.
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ISO/FDIS 21927-3.2:2021(E)

Selection of the motors shall conform with the following requirements:
— Motors shall conform with the requirements of IEC 60034-1.
— Motor ratings shall be limited by the temperature rise for one class lower than the insulation class
of the motor, as defined in IEC 60085.
— The fan tested in accordance with 5.3.2 shall conform with the stability requirement in C.4.2.2.
4.3 Effectiveness of smoke/hot gas extraction
4.3.1 General
The effectiveness of smoke/hot gas extraction of the fan is the ability to continue to extract the required
volume flow at high temperature.
4.3.2 Gas flow and pressure maintenance during smoke and heat extraction test
The effectiveness of smoke/hot gas extraction is demonstrated by conformance with the performance
requirements in C.5, when tested according to 5.4.
4.4 Resistance to fire
The fan is shown to be functioning satisfactorily by its continued ability to provide the initial volume or
pressure within the defined limits in C.5, when tested according to 5.5.
The test result shall be classified in accordance with EN 13501-4.
4.5 Ability to open under environmental conditions
4.5.1 Opening under wind load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with 5.6.
4.5.2 Opening under snow load within a given time
When the fan is fitted with shutter, louvers or dampers, their ability to open under environmental
conditions shall be demonstrated by fulfilling the requirements in E.5 when tested in accordance with 5.6.
4.6 Durability of operational reliability
Durability of operational reliability is demonstrated by motor rating according to 4.2.3 when tested
according to 5.7.
5 Testing, assessment and sampling methods
5.1 General
PSHC ventilator (fan), tests shall be carried out in accordance with Annexes A, B, C and E.
For each test, a test report shall be prepared in accordance with Annex C.
A fan can be tested completely assembled with ancillaries, for example:
— flexible connection elements;
— anchors (fastenings for mounting to external structure);
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ISO/FDIS 21927-3.2:2021(E)

— airflow operated dampers or external powered dampers;
— shock absorber (anti-vibration mount);
— sound absorber (silencer or acoustic attenuator);
— support construction (e.g. for powered roof or partition fans);
— thermal protection (e.g. PTC thermistor, Thermocouple, Pt100, etc.);
— ON-OFF switch and other electrical ancillaries (e.g. electrical safety box) which are directly mounted
on the fan;
— guide vanes;
— flow deflectors;
— a jet fan shall be tested completely assembled and suspended from a supporting construction in
accordance with the manufacturer’s installation instructions.
For testing of motors alone, tests shall be carried out and test reports prepared in accordance with
Annex D.
5.2 Test of response delay (response time) opening under wind / snow load within
a given time
5.2.1 Wind load
The fan shutter, flaps or louvers shall open in less than 30 s against a horizontally applied load of 200 Pa,
simulated by means of an additional fan blowing on the flap at a suitable velocity, or by any suitable
mechanical means when the fan is tested in accordance with Annex E and/or Annex C.
WARNING — For fans which use the air pressure from the fan to open flaps or louvers:
Due to the temperature rise, the density of air decreases resulting in a corresponding decrease
in the pressure developed. This pressure is needed to open the termination system (flaps or
louvers).
In this case, the laboratory shall perform the wind load test also during the high temperature test.
If fans selected according to Annex A and tested according to Annex C are intended for use with
external, air-pressure operated shutters, the combination shall also be tested with a wind load
according to Annex E.
The operating position can be considered as reached if the volume flow exhausted by the fan
working under wind loads did not decrease by more than 10 % of that exhausted by the fan
working without these loads.
If a fan intended for mounting on an external wall is fitted with external shutters, flaps or
louvers and/or is not protected from wind force acting against it by a deflector or cowl, it shall
be tested in accordance with this Clause. Otherwise, the manufacture shall include a statement
in his instructions that suitable wind guarding shall be fitted by the installer.
5.2.2 Snow load
The fan shutter, flaps or louvers shall open in less than 30 s against a vertically applied load shown
in Table 2, simulated by any suitable mechanical means, when the fan is tested in accordance with
Annex E, at ambient temperature only.
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ISO/FDIS 21927-3.2:2021(E)

Table 2 — Snow load classes
Class Load
Pa
SL 0 0
SL 125 125
SL 250 250
SL 500 500
SL 1 000 1 000
SL A A
The operating position can be considered as reached if the volume flow exhausted by the fan working
under snow loads did not decrease by more than 10 % of that exhausted by the fan working without
these loads.
Where the minimum angle of installation recommended by the supplier exceeds 45° from the
horizontal, the fan takes the classification SL 1 000 without a test, except where snow is prevented from
slipping from the fan, for example by wind deflectors. In this case, the fan shall be tested for a snow load
classification which shall not be less than SL = 2 000 · d, where d is the depth of snow, in metres, which
can be contained with the confines of the deflectors.
5.3 Operational reliability
5.3.1 Application categories
The relevant test methods are those indicated in Table 1 in 4.2.2.
5.3.2 Motor rating
The test method to be applied is in C.4.2.
5.4 Effectiveness of smoke/hot gas extraction: gas flow and pressure maintenance
during smoke and heat extraction test
The test method is given in Annex C.
5.5 Resistance to fire
The test method is given in Annex C.
5.6 Ability to open under environmental conditions: opening under wind or snow load
within a given time
The test method is given in Annex E.
5.7 Durability of operational reliability
Durability of operational reliability is demonstrated by the test method given in 5.3.2.
6 Marking, labelling and packaging
The PSHC ventilator (fan) shall be marked with the following:
— the manufacturer’s name or trademark;
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ISO/FDIS 21927-3.2:2021(E)

— the resistance to fire classification;
— a reference to this document and its year of its publication (i.e. ISO 21927-3:2020), followed by the
generic name of the product "powered smoke and heat control ventilator";
— the model/type;
— power requirements, e.g. power, current, voltage and rotational speed;
— the snow load class where applicable;
— the flow direction inside the fan (motor upstream, downstream or both);
— the direction of the motor shaft (vertical, horizontal or both);
— the minimum flow and maximum temperature of cooling air, where applicable;
— information about electrical connections of motor (e.g. Y or Δ);
— the following statement: "This powered smoke and heat control ventilator shall be installed as per
the manufacturer's instructions.";
— the manufacturer's installation instructions or a reference to a document held by the manufacturer
giving these instructions;
— the date of manufacture (month and year).
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ISO/FDIS 21927-3.2:2021(E)

Annex A
(normative)

Criteria to determine the family of fans in order to select the sizes
to be tested
A.1 Reduction of numbers of tests for PSHC ventilators forming a product range
It is not usually considered necessary to test every size of ventilator in a family of fans, provided that
the following are tested and the family conforms to the rules given in A.3, A.4 and Annex B:
a) the fan with the most highly stressed impeller, and the ventilators with impellers in which the
individual stress in any component, weld or fastening is the highest, as appropriate, if not the same
(see A.4);
b) for fans with motors mounted in an enclosure which restricts the cooling, the worst case shall be
tested; this is the smallest free area of the motor enclosure or the smallest section of exit or entry
airway for cooling air;
c) at least two sizes of fans are tested at their highest rotational speed;
d) the fan with the smallest motor frame size to be used, except for fans where the impeller is not
mounted on the motor shaft and the motors are out of the airstream in ambient air and the cooling
of the motor is not affected by heat transfer from the ventilator or the ventilator construction;
e) if the highest impeller stress levels are determined by geometric similarity conditions from A.4.1,
sufficient sizes of fans to ensure that the
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