Fans - Efficiency classification for fans - Part 4: Driven fans at maximum operating speed (ISO 12759-4:2019)

This Standard establishes only the vocabulary of fork arms and load handling attachments. This document gives no safety requirements of fork arms and load handling attachments. For the purpose of this document, the term attachment describes a device that is mounted to an industrial truck to allow an alternative way to use the lifting system.

Ventilatoren - Effizienzklassifizierung für Ventilatoren - Teil 4: Angetriebene Ventilatoren bei maximaler Betriebsdrehzahl (ISO 12759-4:2019)

Diese Internationale Norm legt ein System für die Klassifizierung des Ventilator-Wirkungsgrads bei allen Ventilatortypen fest, die von einem Motor mit einer Nennleistung von mindestens 0,125 kW angetrieben werden. Dies bezieht sich nur auf angetriebene Ventilatoren, aber nicht auf das System (Endprodukt des Originalgeräteherstellers, also z. B. Kastenventilatoren und Dachventilatoren oder Lüftungsanlagen), in das diese eingebaut sind. In diesem Dokument wird eine Reihe von verschiedenen Verfahren zur Klassifizierung des Ventilator-Wirkungsgrads bzw. zur Anwendung der Mindestwirkungsgradgrenze (en: minimum efficiency limit; MEL) beschrieben. Diese Verfahren werden in den folgenden Dokumenten beschrieben:
- ISO 12759 3;
- dieses Dokument (ISO 12759 4);
- ISO 12759 5;
- ISO 12759 6.
Es wird kein Verfahren zum Vergleich dieser Klassifizierungen und MELs beschrieben.

Ventilateurs - Classification du rendement des ventilateurs - Partie 4: Ventilateurs entraînés à vitesse maximale de fonctionnement (ISO 12759-4:2019)

Le présent document établit un système de classification du rendement de tous les types de ventilateurs entraînés par des moteurs dont la puissance nominale est de 125 kW et au-delà. Il est applicable aux ventilateurs (entraînés) uniquement. Il n'est pas applicable au système dans lequel les ventilateurs sont installés (produits finis du fabricant d'équipement d'origine, par exemple, les ventilateurs en caisson, les ventilateurs de toiture ou le système de ventilation). Le présent document décrit un nombre de procédures variées permettant de classifier le rendement d'un ventilateur ou d'appliquer une limite de rendement minimale (MEL). Ces procédures sont décrites dans:
— ISO 12759‑3;
— le présent document (ISO 12759‑4);
— ISO 12759‑5;
— ISO 12759‑6.
Il n'existe pas de méthode décrite permettant de comparer ces classifications et les MEL.

Ventilatorji - Klasifikacija učinkovitosti ventilatorjev - 4. del: Ventilatorji s pogonom pri največji obratovalni hitrosti (ISO 12759-4:2019)

Ta standard določa le besedišče vilic in priključkov za pretovarjanje. Dokument ne vsebuje varnostnih zahtev za vilice in priključke za pretovarjanje. V tem dokumentu izraz priključek opisuje napravo, nameščeno na industrijski tovornjak, ki omogoča alternativni način uporabe dvižnega sistema.

General Information

Status
Published
Public Enquiry End Date
24-Jul-2018
Publication Date
12-Jan-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Dec-2019
Due Date
16-Feb-2020
Completion Date
13-Jan-2020

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SLOVENSKI STANDARD
SIST EN ISO 12759-4:2020
01-februar-2020
Nadomešča:
SIST EN ISO 12759:2015

Ventilatorji - Klasifikacija učinkovitosti ventilatorjev - 4. del: Ventilatorji s pogonom

pri največji obratovalni hitrosti (ISO 12759-4:2019)

Fans - Efficiency classification for fans - Part 4: Driven fans at maximum operating speed

(ISO 12759-4:2019)

Ventilatoren - Effizienzklassifizierung für Ventilatoren - Teil 4: Angetriebene Ventilatoren

bei maximaler Betriebsdrehzahl (ISO 12759-4:2019)

Ventilateurs - Classification du rendement des ventilateurs - Partie 4: Ventilateurs

entraînés à vitesse maximale de fonctionnement (ISO 12759-4:2019)
Ta slovenski standard je istoveten z: EN ISO 12759-4:2019
ICS:
23.120 Zračniki. Vetrniki. Klimatske Ventilators. Fans. Air-
naprave conditioners
SIST EN ISO 12759-4:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 12759-4:2020
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SIST EN ISO 12759-4:2020
EN ISO 12759-4
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2019
EUROPÄISCHE NORM
ICS 23.120 Supersedes EN ISO 12759:2015
English Version
Fans - Efficiency classification for fans - Part 4: Driven fans
at maximum operating speed (ISO 12759-4:2019)

Ventilateurs - Classification du rendement des Ventilatoren - Effizienzklassifizierung für Ventilatoren

ventilateurs - Partie 4: Ventilateurs entraînés à vitesse - Teil 4: Angetriebene Ventilatoren bei maximaler

maximale de fonctionnement (ISO 12759-4:2019) Betriebsdrehzahl (ISO 12759-4:2019)

This European Standard was approved by CEN on 4 October 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12759-4:2019 E

worldwide for CEN national Members.
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SIST EN ISO 12759-4:2020
EN ISO 12759-4:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 12759-4:2020
EN ISO 12759-4:2019 (E)
European foreword

This document (EN ISO 12759-4:2019) has been prepared by Technical Committee ISO/TC 117 "Fans"

in collaboration with Technical Committee CEN/TC 156 “Ventilation for buildings” the secretariat of

which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by May 2020, and conflicting national standards shall be

withdrawn at the latest by May 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 12759:2015.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 12759-4:2019 has been approved by CEN as EN ISO 12759-4:2019 without any

modification.
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SIST EN ISO 12759-4:2020
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SIST EN ISO 12759-4:2020
INTERNATIONAL ISO
STANDARD 12759-4
First edition
2019-10
Fans — Efficiency classification for
fans —
Part 4:
Driven fans at maximum operating
speed
Ventilateurs — Classification du rendement des ventilateurs —
Partie 4: Ventilateurs entraînés à vitesse maximale de fonctionnement
Reference number
ISO 12759-4:2019(E)
ISO 2019
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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 2019 – All rights reserved
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
Contents  Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1  Scope ................................................................................................................................................................................................................................. 1

2  Normative references ...................................................................................................................................................................................... 1

3  Terms and definitions ..................................................................................................................................................................................... 1

4  Symbols .......................................................................................................................................................................................................................... 5

5  General information ......................................................................................................................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Use of installation categories ...................................................................................................................................................... 6

5.3 Efficiency calculation ......................................................................................................................................................................... 7

5.4 Tolerances ................................................................................................................................................................................................... 8

6  Ratings............................................................................................................................................................................................................................. 8

6.1 General ........................................................................................................................................................................................................... 8

6.2 Driven fans .................................................................................................................................................................................................. 8

6.3 Axial, forward curved centrifugal, radial and mixed flow driven fan efficiency grades ........... 9

6.4 Centrifugal backward bladed fan with and without housing driven fan efficiency grades 11

6.5 Cross flow driven fan efficiency grades ..........................................................................................................................13

Annex A (normative) Examples of applying efficiency lines to driven fans ..............................................................15

Annex B (informative) Compensation factors ..........................................................................................................................................18

Annex C (informative) The variation of fan performance between installation categories ....................19

Annex D (informative) Selection of fans for best efficiency .......................................................................................................20

Annex E (informative) Explanatory note .......................................................................................................................................................23

Bibliography .............................................................................................................................................................................................................................25

© ISO 2019 – All rights reserved iii
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(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 117, Fans.

This first edition of ISO 12759-4, together with ISO 12759-1, ISO 12759-2, ISO 12759-3, ISO 12759-5

and ISO 12759-6 , cancels and replaces ISO 12759:2010, which has been technically revised. It also

incorporates the Amendment ISO 12759:2010/Amd.1:2013.
A list of all parts in the ISO 12759 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.

1) Under preparation. Stage at the time of publication: ISO/DIS 12759-5:2019.
2) Under preparation. Stage at the time of publication: ISO/CD 12759-6:2019.
iv © ISO 2019 – All rights reserved
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
Introduction

The last decade has seen an escalation in the price and an increasing recognition of the finite life of

many of the fossil fuels currently used. There is also a belief by many that climatic change is due to

increasing levels of carbon dioxide in the atmosphere. This has led to many nations reviewing methods

of energy generation and usage.

To maintain economic growth there is therefore a need to promote energy efficiency. This requires

better selection of equipment by users and thus better design of this equipment by manufacturers.

Fans of all types are used for ventilation, air conditioning, process engineering – drying, pneumatic

conveying – combustion air supply and agriculture. Indeed, the energy use of fans has been calculated

to account for nearly 20 % of the global electricity usage.

The fan industry is global in nature, with a considerable degree of exporting and licensing. To ensure

that the definitive fan performance characteristics are common throughout the world, a series of

standards has been developed. It is the belief of the industry that there is now a need for minimum

efficiency standards to be recognised. To encourage their implementation, a classification system is

proposed which incorporates a series of efficiency bands. With improvements in technology and

manufacturing processes, the minimum efficiency levels could be reviewed and increased over time.

This document can be used by legislators or regulatory bodies for defining future energy-saving targets.

© ISO 2019 – All rights reserved v
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SIST EN ISO 12759-4:2020
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SIST EN ISO 12759-4:2020
INTERNATIONAL STANDARD ISO 12759-4:2019(E)
Fans — Efficiency classification for fans —
Part 4:
Driven fans at maximum operating speed
1  Scope

This document establishes a system for the classification of fan efficiency for all fan types driven by

motors of nominal rating 0,125 kW and above. It applies to driven fans only, but not to the system

(finished original equipment manufacturer’s product, for example box fans and roof fans or ventilation

system) in which they might be installed. This document describes a number of different procedures

to classify the efficiency of a fan or to apply a minimum efficiency limit (MEL). Those procedures are

described in:
— ISO 12759-3;
— this document (ISO 12759-4);
— ISO 12759-5;
— ISO 12759-6.
There is no method described to compare these classifications and MEL’s.
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 5801:2017, Fans — Performance testing using standardized airways

ISO 13348:2007, Industrial fans — Tolerances, methods of conversion and technical data presentation

3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
fan

rotary-bladed machine that receives mechanical energy and utilizes it by means of one or more

impellers fitted with blades to maintain a continuous flow of air or other gas passing through it and

whose work per unit mass does not normally exceed 25 kJ/kg

Note 1 to entry: Fans are defined according to their installation category, function, fluid path and operating

conditions (see ISO 13349).
[SOURCE: ISO 13349:2010, 3.1.1, — Notes to entry 1 and 3 were deleted.]
© ISO 2019 – All rights reserved 1
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
3.2
fan size
nominal diameter of the impeller
3.3
drive

mechanism used to power the fan which includes the motor, belt, couplings, chains, transmission

and VFDs
EXAMPLE Transmission drive and motor drive.
3.4
driven fan

impeller fitted to or connected to a motor, with or without a drive mechanism, housing or means of

variable speed drive
Note 1 to entry: See Figure 1.
3.5
air
working fluid for tests with standardized airways shall be atmospheric air
[SOURCE: ISO 5801:2017, 3.1]
3.6
installation category A
installation with free inlet and free outlet with a partition

[SOURCE: ISO 13349:2010, 3.4.1, modified — References to ISO 5801 and ISO 5802 were deleted.]

3.7
installation category B
installation with free inlet and ducted outlet

[SOURCE: ISO 13349:2010, 3.4.2, modified — References to ISO 5801 and ISO 5802 were deleted.]

3.8
installation category C
installation with ducted inlet and free outlet

[SOURCE: ISO 13349:2010, 3.4.3, modified — References to ISO 5801 and ISO 5802 were deleted.]

3.9
installation category D
installation with ducted inlet and ducted outlet

[SOURCE: ISO 13349:2010, 3.4.4, modified — References to ISO 5801 and ISO 5802 were deleted.]

3.10
density at fan inlet

fluid density calculated from the absolute pressure and the static temperature at the fan inlet

3.11
fan pressure

difference between the stagnation pressure at the fan outlet and the stagnation pressure at the fan inlet

2 © ISO 2019 – All rights reserved
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
3.12
mass flow rate

mean value, over time, of the mass of air which passes through the specified airway cross-section per

unit of time
3.13
inlet volume flow rate

mass flow rate at the inlet divided by the corresponding mean value, over time, of the average density

at the inlet
3.14
fan work per unit mass
increase in mechanical energy per unit mass of fluid passing through the fan
3.15
compressibility coefficient

ratio of the mechanical work done by the fan on the air to the work that would be done on an

incompressible fluid with the same mass flow, inlet density and pressure ratio
3.16
fan air power

conventional output power which is the product of the mass flow rate and the fan work per unit mass,

or the product of the inlet volume flow rate, the compressibility coefficient and the fan pressure

3.17
fan static air power

conventional output power which is the product of the mass flow rate and the fan work per unit mass,

or the product of the inlet volume flow rate, the compressibility coefficient and the fan pressure

3.18
impeller power
mechanical power supplied to the fan impeller
[SOURCE: ISO 5801:2017, 3.45]
3.19
fan shaft power
mechanical power supplied to the fan shaft
[SOURCE: ISO 5801:2017, 3.46, modified — Note 1 to entry was deleted.]
3.20
motor output power
shaft power output of the motor or other prime mover
[SOURCE: ISO 5801:2017, 3.47]
© ISO 2019 – All rights reserved 3
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
3.21
motor input power

electrical input power supplied at the terminals of an electric motor drive without a variable speed drive

[SOURCE: ISO 5801:2017, 3.48]
3.22
drive/control electrical input power
power supplied by electrical mains or equivalent energy supply to a motor system
3.23
fan impeller efficiency
fan air power divided by the impeller power

[SOURCE: ISO 5801:2017, 3.50, modified — References to quantities and formula deleted.]

3.24
fan shaft efficiency
fan air power divided by the fan shaft power

[SOURCE: ISO 5801:2017, 3.51, modified — References to quantities and formula deleted.]

3.25
overall efficiency for a fan without a variable speed drive

fan air power divided by the motor input power for the fan and motor without a variable speed drive

Note 1 to entry: The efficiency should be referred to the installation category, see Figure 2 and ISO 13349.

Note 2 to entry: For the purposes of this document efficiency should be expressed as a proportion of unity. To

obtain a percentage value multiply the efficiency result by 100.
Note 3 to entry: The motor input power as defined in 3.21.
3.26
overall efficiency for a fan with a variable speed drive

fan air power divided by the motor input power for the fan and motor combination with a variable

speed drive

Note 1 to entry: The efficiency should be referred to the installation category, see Figure 2 and ISO 13349.

Note 2 to entry: For the purposes of this document efficiency should be expressed as a proportion of unity. To

obtain a percentage value multiply the efficiency result by 100.
Note 3 to entry: The motor input power as defined in 3.22.
3.27
overall static efficiency for a fan without a variable speed drive

fan static air power divided by the motor input power for the fan and motor without a variable speed drive

3.28
overall static efficiency for a fan with a variable speed drive
esd

fan static air power divided by the motor input power for the fan and motor combination with a variable

speed drive
4 © ISO 2019 – All rights reserved
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
3.29
optimum efficiency
opt

maximum efficiency achieved on the fan air characteristic with all operational parameters, except the

air system resistance, being fixed
3.30
fan motor efficiency grade
FMEG
efficiency grade for a driven fan
Note 1 to entry: The definitions given in 3.25 to 3.28 shall apply.
4  Symbols
Symbol Term Unit
k compressibility coefficient
N grade number
P fan shaft power W
P motor input power W
P drive/control electrical input power W
P motor output power W
P impeller power W
P fan air power W
P fan static air power W
p atmospheric pressure Pa
p dynamic pressure at a point Pa
p fan pressure Pa
p fan static pressure Pa
p absolute stagnation pressure at a point Pa
q mass flow rate kg/s
q inlet volume flow rate m /s
W fan work per unit mass J/kg
η fan shaft efficiency Expressed as a decimal
η overall efficiency Expressed as a decimal
η overall efficiency for a fan with VSD Expressed as a decimal
η overall static efficiency Expressed as a decimal
η overall static efficiency for a fan with VSD Expressed as a decimal
esd
η optimum efficiency Expressed as a decimal
opt
η fan impeller efficiency Expressed as a decimal
ρ density at fan inlet kg/m

NOTE Efficiency in percent (%) divided by 100 equals the efficiency expressed as a decimal.

5  General information
5.1  General

Fans range from the purpose-built single fan to the series-produced certified ranges manufactured in

large quantities. A fan may be a motor attached to a drive system attached to an impeller within an

© ISO 2019 – All rights reserved 5
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)

impeller casing, if so supplemented by a volume control such as a variable speed control or guide vanes

(driven fan), see Figure 1.

The variation in design has led to efficiency being defined in a number of ways to suit the demands of

the fan type and the market place.
Key
1 electrical input power P
2 variable speed device loss (heat)
3 motor losses (heat)
4 belt losses (heat)
5 bearing losses (heat)
6 impeller and casing aerodynamic losses (heat)
7 volume flow and pressure P (air power)
The variable speed device might or might not be fitted. See Clause 6.
Figure 1 — Example of a driven fan showing power losses
5.2  Use of installation categories

Fan efficiency ratings are frequently specific to each standardised installation category.

When a fan is designed for a single installation category, its rated efficiency grade shall refer to that

particular installation category, and this shall be clearly identified.

When a fan is suitable for use with different installation categories, the fan efficiency grade shall be

based on the efficiency ratings referring to the most suitable installation category.

To determine the operating point of the fan, four installation categories are considered, see Figure 2.

For details of the required test methods refer to the following subclauses of ISO 5801:

— category A installations – ISO 5801:2017, 6.1;
— category B installations – ISO 5801:2017, 6.2;
— category C installations – ISO 5801:2017, 6.3;
— category D installations – ISO 5801:2017, 6.4.
6 © ISO 2019 – All rights reserved
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)

The standardised installation category used for rating the fan shall be clearly stated (see Annex C).

The motor input power and motor output power shall be measured or determined using methods given

in ISO 5801.
Installation category E is not included in this document.
Figure 2 — Installation categories
5.3  Efficiency calculation
See ISO 5801:2017, 15.2.

For driven fans, where the input power can be determined, the overall efficiency is given by Formula (1)

for fans without a variable speed drive and Formula (2) for fans with variable speed drives.

η =PP/ (1)
eu e
η =PP/ (2)
ed ued

The overall static efficiency can be calculated by substituting the static air power into Formulae (1) and

(2) so that the overall static efficiency is given by Formula (3) for fans without a variable speed drive

and Formula (4) for fans with variable speed drives.
η =PP/ (3)
es us e
η =PP/ (4)
esdused
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SIST EN ISO 12759-4:2020
ISO 12759-4:2019(E)
5.4  Tolerances

At each stage of the fan design and manufacturing cycle, including conversion from prototype

performance data or calculation, and fabrication and testing of a purpose-designed fan, finite

uncertainties will prevail and acceptance tolerances shall be applied.

Any test for fan performance is subject to error, and the range within which these testing errors

may be expected to lie is defined numerically as the uncertainty of measurement. In addition, the

true performance of the fan (if it could be ascertained) would be found to differ from that of another

nominally identical fan, owing to inevitable variations in manufacture. The expected range of this

manufacturing variation shall be added to the uncertainty of measurement to determine the minimum

tolerance required for a performance specification.

For the purposes of this document the tolerances given in ISO 13348:2007, Clauses 5 and 6, shall apply.

6  Ratings
6.1  General

The variation of fan type and drive option leads to efficiency being derived in different ways. For

grading purposes, the efficiency for driven fans has been defined as a function of motor input power.

The following is a guide to the optimum efficiency (best efficiency point) levels that are achievable by the

fan types addressed by this document. The minimum levels of acceptability are dependent on consultation

between regulators and manufacturers’ representatives or local legislation where this exists.

The efficiency grade for a fan is based on its performance characteristics at maximum permissible

rotational speed to obtain its best efficiency point.

Further information on the subject of fan efficiency can be found in Annexes D and E.

6.2  Driven fans

The efficiency grades for driven fans are shown in Figures 3, 4 and 5. The variation of optimum

efficiency and fan motor efficiency grade (FMEG) is shown as a function of input power and design.

In cases where a volume control device is necessary, a variable speed drive is the best option, as it is the

most efficient method for adjustment to different operating points. Other options for volume control

such as guide vanes or control valves are less efficient.

The FMEG (e.g. FMEG55) of a given fan at its best efficiency point at full speed shall be the value

calculated according to Annex A, for the relevant input power.

The curves of FMEGs are based on impeller and motor combinations. If a control device is used then the

efficiency data can be revised by the correction values for controls in
...

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