ISO 13351
(Main)Fans — Dimensions
Fans — Dimensions
ISO 13351:2009 specifies the dimensions of the circular and rectangular flanges of general‑purpose fans, as well as the fan size designations. It is not applicable to cross‑flow fans or to fan appliances used for individual household or similar applications.
Ventilateurs — Dimensions
L'ISO 13351:2009 spécifie les dimensions des brides circulaires et des brides rectangulaires pour les ventilateurs à usage courant, ainsi que les désignations de la taille des ventilateurs. Elle ne s'applique pas aux ventilateurs tangentiels, ni aux dispositifs de ventilation utilisés pour des applications domestiques individuelles ou similaires.
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Standards Content (Sample)
FINAL DRAFT
International
Standard
ISO/FDIS 13351
ISO/TC 117
Fans — Dimensions
Secretariat: BSI
Ventilateurs — Dimensions
Voting begins on:
2024-05-29
Voting terminates on:
2024-07-24
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
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ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 13351:2024(en) © ISO 2024
FINAL DRAFT
ISO/FDIS 13351:2024(en)
International
Standard
ISO/FDIS 13351
ISO/TC 117
Fans — Dimensions
Secretariat: BSI
Ventilateurs — Dimensions
Voting begins on:
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2024
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/FDIS 13351:2024(en) © ISO 2024
ii
ISO/FDIS 13351:2024(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .1
3.2 Symbols .3
4 Requirements . 4
4.1 General .4
4.2 Circular flanges .4
4.3 Rectangular flanges .7
4.4 Designation of fan size .11
Bibliography .13
iii
ISO/FDIS 13351:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 117, Fans, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 156, Ventilation for buildings, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 13351:2009), which has been technically
revised.
The main changes are as follows:
— added to the sizes of the heavy-duty fans in Table 3;
— aligned definitions and symbols to ISO 13349-1;
— clarified Figure 3 for mixed flow fan.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO/FDIS 13351:2024(en)
Introduction
This document gives dimensional details of circular and rectangular flanges of fans in addition to specifying
1)
the fan size designation. For circular flanges, the values specified in ISO 6580 have been retained for light-
duty fans, in parallel with those values given in Tables 3 and 4 for medium- and heavy-duty fans.
While it does not constrain the manufacturer's choice of flange details, this document facilitates
interchangeability, thereby helping reduce technical barriers to trade.
Throughout this document, the principal dimensions are based on the rounded values of preferred numbers
given in ISO 497.
1) Cancelled and replaced by ISO 13351.
v
FINAL DRAFT International Standard ISO/FDIS 13351:2024(en)
Fans — Dimensions
1 Scope
This document specifies the dimensions of the circular and rectangular flanges of general-purpose fans, as
well as the fan size designations. It is not applicable to cross-flow fans or to fan appliances used for individual
household or similar applications.
For circular flanges, it provides for three different flange series: one for light-duty casing thicknesses,
another for medium-duty fans and the third for heavy-duty fans as used on sea-going vessels or in heavy
industry.
In order not to restrict fan design unduly, only the pitch diameter, hole numbers and hole diameters are
specified. Flange thickness, as well as internal and external flange diameters, can be chosen freely within
the limits of good engineering practice.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3, Preferred numbers — Series of preferred numbers
ISO 13349-1, Fans — Vocabulary and definitions of categories — Part 1: Vocabulary
ISO 13349-2, Fans — Vocabulary and definitions of categories — Part 2: Categories
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 13349-1, ISO 13349-2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Terms and definitions
3.1.1
light‑duty fan
fan suitable for air that is non-toxic, not saturated, non-corrosive, non-flammable, free from abrasive
particles, and not exceeding a temperature of 80 °C, or 40 °C if the motor or the fan bearings are in the air
stream, and for pressures up to 2 kPa
Note 1 to entry: See Table 1.
ISO/FDIS 13351:2024(en)
3.1.2
medium‑duty fan
fan designed for pressures up to 10 kPa.
Note 1 to entry: Applications that require a robust design can be referred to as "medium duty", such as in marine
applications.
3.1.3
heavy‑duty fan
fan designed for pressures up to 40 kPa.
Note 1 to entry: Applications that require a more robust design can be referred to as "heavy duty", such as in marine
applications.
3.1.4
nominal impeller tip diameter
D
diameter of the impeller tip on which the design of the fan is based
Note 1 to entry: See Figures 1 to 3.
b
D may be smaller than, larger than or equal to D .
R
Figure 1 — Impeller — Centrifugal fan
ISO/FDIS 13351:2024(en)
b
D may be smaller than, larger than or equal to D .
R
Figure 2 — Impeller — Axial‑flow fan
b
D may be smaller than, larger than or equal to D .
R
Figure 3 — Impeller — Mixed‑flow fan
3.2 Symbols
Symbol Parameter Unit
D nominal impeller tip diameter mm
a
D impeller tip diameter mm (see Figures 1 to 3)
R
d internal duct diameter mm
d pitch circle diameter mm
d hole diameter mm
d bolt diameter mm
d washer diameter mm
e casing thickness mm
g hole offset mm
a
Reference ISO 13349-1:2022, 3.7.4 i.e. maximum diameter measured over the tips of the blades of the impeller.
ISO/FDIS 13351:2024(en)
Symbol Parameter Unit
l arc length between bolt holes mm
N number of holes
P pitch mm
α angle between bolt holes degrees
a
Reference ISO 13349-1:2022, 3.7.4 i.e. maximum diameter measured over the tips of the blades of the impeller.
4 Requirements
4.1 General
This document adopts the Renard R 20 series, according to ISO 17, and preferred numbers in ISO 497 as the
nominal dimensions (D) for impeller tip diameters, the inside diameters of circular flanges and the inside
lengths of the sides of rectangular flanges. It takes into account the maximum casing thicknesses likely to
be used for general-purpose fans, as well as typical manufacturing tolerances representative of engineering
“good practice”.
The smallest practical pitch circle diameter can be related to the inside diameter of the casing, the casing
thickness, the size of the weld fillet or bend radius at the junction of the flange and the casing, and the normal
washer diameter. Light-duty circular flanges might not be suitable for the use of open-ended spanners in all cases.
This document accepts that the number and diameter of bolts or screws cannot be established on a
theoretical basis. Practical experience of satisfactory service, optimum cost of installation and manufacture,
as well as dimensional tolerances of production are the most important considerations.
The dimensions of circular and rectangular flanges are given in sizes corresponding to nominal diameters
from 100 mm to 2 000 mm (3 550 mm for heavy duty fans, Table 3). In the smaller sizes (below about
200 mm) flange details may be determined by the customer's specification. However, where this is not the
case, then the specifications of this document are to be applied.
4.2 Circular flanges
The number of flange holes is divisible by four to permit the orientation of cylindrical cased fans at positions
of 90°. The holes are disposed equally on each side of the centrelines of the fan. This permits a flange to be
divided in half if a split casing is required. It also allows better access to the fixings on the remote side of a
fan in a confined installation.
When an intermediate fan size is required, the R 40 series in accord
...
2023-12-18
ISO/DISFDIS 13351:2023(E)
ISO/TC 117
Secretariat: BSI
Date: 2024-05-14
Fans — Dimensions
Ventilateurs — Dimensions
FDIS stage
ISO/DISFDIS 13351:2023(E2024(en)
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
EmailE-mail: copyright@iso.org
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii
ii
ISO/DISFDIS 13351:2023(E2024(en)
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 4
4 Requirements . 5
4.1 General. 5
4.2 Circular flanges . 5
4.3 Rectangular flanges . 10
4.4 Designation of fan size . 16
Bibliography . 18
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Requirements . 3
4.1 General. 3
4.2 Circular flanges . 4
4.3 Rectangular flanges . 7
4.4 Designation of fan size . 12
Bibliography 13
iii
iii
ISO/DISFDIS 13351:2023(E2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee 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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that this
may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 117, Fans, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 156, Ventilation for buildings, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 13351:2009), which has been technically
revised.
The main changes are as follows:
— — added to the sizes of the heavy-duty fans in Table 3Table 3;
— — aligned definitions and symbols to ISO 13349-1;
— — clarified Figure 3Figure 3 for mixed flow fan.
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.htmlwww.iso.org/members.html.
iv
iv
ISO/DISFDIS 13351:2023(E2024(en)
Introduction
This document gives dimensional details of circular and rectangular flanges of fans in addition to specifying
1)
the fan size designation. For circular flanges, the values specified in ISO 6580 have been retained for light-
duty fans, in parallel with those values given in Tables 3Tables 3 and 44 for medium- and heavy-duty fans.
While it does not constrain the manufacturer's choice of flange details, this document facilitates
interchangeability, thereby helping reduce technical barriers to trade.
Throughout this document, the principal dimensions are based on the rounded values of preferred numbers
given in ISO 497.
1)
Cancelled and replaced by ISO 13351.
v
v
ISO/FDIS 13351:2024(en)
Fans — Dimensions
1 Scope
This document specifies the dimensions of the circular and rectangular flanges of general-‑purpose fans, as
well as the fan size designations. It is not applicable to cross-‑flow fans or to fan appliances used for individual
household or similar applications.
For circular flanges, it provides for three different flange series: one for light-‑duty casing thicknesses, another
for medium-‑duty fans and the third for heavy-‑duty fans as used on sea-going vessels or in heavy industry.
In order not to restrict fan design unduly, only the pitch diameter, hole numbers and hole diameters are
specified. Flange thickness, as well as internal and external flange diameters, can be chosen freely within the
limits of good engineering practice.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3, Preferred numbers — Series of preferred numbers
ISO 13349--1, Fans — Vocabulary and definitions of categories — Part 1: Vocabulary
ISO 13349--2, Fans — Vocabulary and definitions of categories — Part 2: Categories
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 13349--1, ISO 13349--2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1 Terms and definitions
3.1.1
light-‑duty fan
fan suitable for air that is non-toxic, not saturated, non-corrosive, non-flammable, free from abrasive particles,
and not exceeding a temperature of 80 °C, or 40 °C if the motor or the fan bearings are in the air stream, and
for pressures up to 2 kPa
Note1 Note 1 to entry: See Table 1.Table 1.
3.1.2
medium-‑duty fan
fan designed for pressures up to 10 kPa.
ISO/FDIS 13351:2024(en)
Note: applications 1 to entry: Applications that require a robust design can be referred to as "medium duty"", such as in
marine applications .
3.1.3
heavy-‑duty fan
fan designed for pressures up to 40 kPa.
Note: applications 1 to entry: Applications that require a more robust design can be referred to as "heavy duty"", such as
in marine applications.
3.1.4
nominal impeller tip diameter
D
diameter of the impeller tip on which the design of the fan is based
Note 1 to entry: See Figures 1Figures 1 to 3.3.
ISO/FDIS 13351:2024(en)
b
D may be smaller than, larger than or equal to D .
R
Figure 1 — Impeller — Centrifugal fan
b
D may be smaller than, larger than or equal to DR.
Figure 2 — Impeller — Axial-flow fan
ISO/FDIS 13351:2024(en)
b
D may be smaller than, larger than or equal to D .
R
Figure 3 — Impeller — Mixed-flow fan
3.2 Symbols
Symbol Parameter Unit
D nominal impeller tip diameter mm
a
D impeller tip diameter mm (see Figures 1 to 3)mm (see
R
Figures 1 to 3)
d0 internal duct diameter mm
d pitch circle diameter mm
d2 hole diameter mm
d3 bolt diameter mm
ISO/FDIS 13351:2024(en)
Symbol Parameter Unit
d4 washer diameter mm
e casing thickness mm
g hole offset mm
l arc length between bolt holes mm
N number of holes
P pitch mm
α angle between bolt holes degrees
a
Reference ISO 13349-1:2022, 3.7.4 i.e. maximum diameter measured over the tips of the blades of the impeller.
4 Requirements
4.1 General
This document adopts the Renard R 20 series, according to ISO 17, and preferred numbers in ISO 497 as the
nominal dimensions (D) for impeller tip diameters, the inside diameters of circular flanges and the inside
lengths of the sides of rectangular flanges. It takes into account the maximum casing thicknesses likely to be
used for general-‑purpose fans, as well as typical manufacturing tolerances representative of engineering
“good practice”.
The smallest practical pitch circle diameter can be related to the inside diameter of the casing, the casing
thickness, the size of the weld fillet or bend radius at the junction of the flange and the casing, and the normal
washer diameter. Light-‑duty circular flanges might not be suitable for the use of open-‑ended spanners in all
cases.
This document accepts that the number and diameter of bolts or screws cannot be established on a theoretical
basis. Practical experience of satisfactory service, optimum cost of installation and manufacture, as well as
dimensional tolerances of production are the most important considerations.
The dimensions of circular and rectangular flanges are given in sizes corresponding to nominal diameters
from 100 mm to 2 000 mm (3 550 mm for heavy duty fans, Table 3).Table 3). In the smaller sizes (below
about 200 mm) flange details may be determined by the customer's specification. However, where this is not
the case, then the specifications of this document are to be applied.
4.2 Circular flanges
The number of flange holes is divisible by four to p
...
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