Fans — System effects and system effect factors

This document deals with the likely degradation of air performance of fans tested in standardized airways in accordance with ISO 5801 when compared with the performance of fans tested under actual site conditions. It deals with the performance of a number of generic types of fan and fittings. The results given are intended as guidelines and only provide trends, as the system effect depends on the exact geometry of the fan and disturbing component. The test data presented in this document are taken from an extensive experimental program conducted 20 years ago by NEL (National Engineering Laboratory, UK), mainly on axial and centrifugal fans. Data are also taken from several research projects financially supported by ASHRAE, some of them being carried out in the AMCA laboratory in Chicago, as well as from results published previously by individual fan manufacturers.

Ventilateurs — Effet système et facteurs d’effet système

Le présent document traite de la dégradation probable de la performance aéraulique des ventilateurs soumis à essai sur circuits standards conformément à l'ISO 5801 par rapport aux performances de ventilateurs soumis à essai dans des conditions réelles sur site. Il traite des performances d'un certain nombre de ventilateurs et de composants génériques. Les résultats obtenus constituent des lignes directrices et ne fournissent que des tendances, car l'effet système dépend de la géométrie exacte du ventilateur et du composant perturbateur. Les données présentées dans le présent document sont issues d'un vaste programme expérimental mené il y a 20 ans par le laboratoire national britannique pour l'ingénierie (NEL), principalement sur des ventilateurs axiaux et centrifuges. Les données sont aussi tirées de plusieurs projets de recherche financés par l'ASHRAE, dont certains sont menés dans le laboratoire de l'AMCA à Chicago, ainsi que de résultats publiés par des fabricants de ventilateurs individuels.

General Information

Status
Published
Publication Date
06-Sep-2020
Technical Committee
Current Stage
6060 - International Standard published
Start Date
07-Sep-2020
Completion Date
07-Sep-2020
Ref Project

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TECHNICAL ISO/TR
REPORT 16219
First edition
2020-09
Fans — System effects and system
effect factors
Ventilateurs — Effet système et facteurs d’effet système
Reference number
ISO/TR 16219:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TR 16219:2020(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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TR 16219:2020(E)
Contents Page

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

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

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

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

3 Terms, definitions and symbols ............................................................................................................................................................ 1

4 Origin of fan system effects ....................................................................................................................................................................... 2

5 Definitions of system effect factor (SEF) ...................................................................................................................................... 4

5.1 Inlet SEF ........................................................................................................................................................................................................ 4

5.2 Outlet system effect ............................................................................................................................................................................ 6

6 Examples of inlet SEF ....................................................................................................................................................................................... 9

6.1 Introduction .............................................................................................................................................................................................. 9

6.2 Axial fans ...................................................................................................................................................................................................10

6.2.1 Experimental setups ..................................................................................................................................................10

6.2.2 Results ....................................................................................................................................................................................15

6.3 Centrifugal and mixed-flow fans ...........................................................................................................................................17

6.3.1 Experimental setups ..................................................................................................................................................17

6.3.2 Results ....................................................................................................................................................................................24

7 Examples of outlet SEF ................................................................................................................................................................................30

7.1 Axial fans ...................................................................................................................................................................................................30

7.1.1 General...................................................................................................................................................................................30

7.1.2 Experimental setups ..................................................................................................................................................30

7.1.3 Results ....................................................................................................................................................................................30

7.2 Centrifugal and mixed-flow fans ...........................................................................................................................................32

7.2.1 Experimental setups ..................................................................................................................................................32

7.2.2 Results ....................................................................................................................................................................................33

8 Reducing system effects .............................................................................................................................................................................34

8.1 General ........................................................................................................................................................................................................34

8.2 Inlet effects ..............................................................................................................................................................................................34

8.2.1 General...................................................................................................................................................................................34

8.2.2 Non-uniform flow ...................................................................... ...................................................................................35

8.2.3 Swirl or vorticity ...........................................................................................................................................................36

8.2.4 Inlet blockage .................. .................................................... .............................................................................................36

8.3 Outlet effects ..........................................................................................................................................................................................39

8.3.1 General...................................................................................................................................................................................39

8.3.2 Insufficient duct length ...........................................................................................................................................39

8.3.3 Outlet obstruction ...................................................................... ..................................................................................40

8.3.4 Non-uniform flow ...................................................................... ...................................................................................40

8.4 Examples of the effects of poor inlet and outlet connections ......................................................................43

9 Conclusions .............................................................................................................................................................................................................44

Annex A (informative) Basic principles on fan performance representation ........................................................45

Annex B (informative) Fan system calculation ........................................................................................................................................73

Bibliography .............................................................................................................................................................................................................................83

© ISO 2020 – All rights reserved iii
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ISO/TR 16219:2020(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 117, Fans.

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 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Introduction

ISO 5801 provides the information for accurately measuring the performance of fans when tested

under standardised laboratory conditions. The ducting where specified ensures a fully developed

symmetrical velocity profile at the fan inlet. There may also be sufficient straight ducting at the fan

outlet to ensure efficient conversion of the distorted velocity profile at the fan outlet to a measurable

stable and homogeneous profile at the measuring station.

This document shows how fan performance is affected by both inlet and outlet connections to it.

System designers must not only look at the ideal performance curve and calculated system pressure

drop but also take into account the losses at the entry and exit points of the fan. These are described in

the document.

The concept of the system effect factor (SEF) was introduced to the fan industry by AMCA in 1973.

Since its inception it has become widely accepted worldwide. In more recent years it has been realized

that the SEF depends not only on the fan type and the fitting geometry but also on the fan design and

manufacturing. Some less efficient fans may sometimes be less sensitive to system effect induced by

poor inlet flow conditions than more efficient fans of the same type.

Furthermore, the origin of the system effect induced by a fitting at the fan inlet is different from the

one due to the same fitting located on the fan outlet. That is why two different definitions of SEF are

proposed in this document according to whether the appurtenance is at the fan inlet or fan discharge.

© ISO 2020 – All rights reserved v
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TECHNICAL REPORT ISO/TR 16219:2020(E)
Fans — System effects and system effect factors
1 Scope

This document deals with the likely degradation of air performance of fans tested in standardized

airways in accordance with ISO 5801 when compared with the performance of fans tested under actual

site conditions. It deals with the performance of a number of generic types of fan and fittings. The

results given are intended as guidelines and only provide trends, as the system effect depends on the

exact geometry of the fan and disturbing component.

The test data presented in this document are taken from an extensive experimental program conducted

20 years ago by NEL (National Engineering Laboratory, UK), mainly on axial and centrifugal fans.

Data are also taken from several research projects financially supported by ASHRAE, some of them

being carried out in the AMCA laboratory in Chicago, as well as from results published previously by

individual fan manufacturers.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and symbols
No terms and definitions are listed in this document.

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/
The following symbols are used:
Symbol Description SI units I-P units
2 2
A Fan outlet area m ft
C System effect (SE) coefficient (see 5.2) Dimensionless Dimensionless
p Conventional pressure loss (see 5.2) Pa in. wg
p Fan pressure Pa in. wg
p Fan dynamic pressure (see Clause 4) Pa in. wg
p Fan static pressure Pa in. wg
p System effect (see 5.2) Pa in. wg
Additional pressure loss due to non-uni-
p Pa in. wg
SEo
form flow (see 5.2)
q Volume flow rate of the fan m /s cfm
S System effect factor Dimensionless Dimensionless
3 0,5
ξ Loss coefficient (see 5.1) (m /s)/(Pa )
3 2
ρ Density of air kg/m lbm/ft
3 2
ρ Standard air density kg/m lbm/ft
std

NOTE The term “fan dynamic pressure” or “dynamic pressure” is used throughout this document and is

equivalent to the term “velocity pressure” as used in some countries.
© ISO 2020 – All rights reserved 1
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ISO/TR 16219:2020(E)
4 Origin of fan system effects

Manufacturers’ fan performance ratings are mostly based on tests carried out in a laboratory under

ideal conditions. Ideal conditions refer to uniform, swirl-free air velocity profiles at fan inlet and outlet,

like those of the test rigs described in ISO 5801 and AMCA 210. In ‘real life’ fan installations, such ideal

conditions may not be present due to improper connection of the fan to the system. Such improper

connections include obstacles at fan inlets and outlets that alter the aerodynamic characteristics of the

fan and lead to deficient performance in relation to catalogue ratings, even when the system pressure

losses have been estimated accurately. The term “system effect” is a measure of this degradation of fan

performance.

The origin of system effect is different at fan outlet and at fan inlet. At the fan outlet, for example in

the case of an improperly connected outlet fitting such as an elbow, damper or duct branch, the system

effect is linked to less-than-optimum non-uniform flow profiles induced by the fan at the entrance to

the fitting (Figure 1). This degraded flow will create more pressure loss across the fitting than would

be the case when measuring the fitting loss assuming uniform homogeneous flow profiles or when

[14]

estimating it from standard handbooks such as the ASHRAE Handbook of Fundamentals .

When the fitting is at the fan inlet, for example an elbow or a fan inlet duct/box (Figure 2), the velocity

profiles at the inlet to the fitting may be uniform and the fitting pressure loss as measured or estimated

from standard handbooks may be valid. However, the flow patterns at the fan inlet (or fitting outlet)

may be disturbed with the presence of a vortex, spin or vena-contracta. This less than optimum flow

condition at fan inlet caused by the fitting will lead to a reorganization of the flow inside the impeller

and therefore a deterioration of fan performance in relation to catalogue ratings. Not only the fan curve

may be affected by this disturbing obstacle but also sometimes, but not always, the fan power curve. A

companion document will be drafted at a later date to show the influence of the inlet obstacles on the

fan power curve for the same configurations of fans and fittings as in this document.

In both cases, the resulting air flow of the fan-system combination deteriorates, but for distinct

physical reasons. For this reason, two different definitions and treatment of fan system effect are

incorporated, depending on whether the fitting is at the fan inlet or fan outlet. It is also recognized

that in some situations, obstacles very close to fan discharge (e.g. side walls at a short distance of a

plenum fan impeller as shown in Figure 20) may also deteriorate fan performance in the same manner

as components located at fan inlet.
Key
1 axial fan
Figure 1 — Non-uniform velocity profiles at fan outlet
2 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Impeller rotation.
Figure 2 — Vortex at fan inlet

An ideal connection to a fan would be one which results in a velocity distribution across the fan inlet

connection plane which is relatively uniformly distributed and without appreciable swirl component,

as shown in Figure 3.
© ISO 2020 – All rights reserved 3
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ISO/TR 16219:2020(E)
a) Ideal p distribution b) Good p distribution
d d
c) Satisfactory p distribution
Key
p mean dynamic pressure of the duct flow

Also satisfactory for flow into fan inlets, but may be unsatisfactory for flow into inlet boxes, may produce swirl

in boxes.

More than 75 % of p readings greater than p /10 (unsatisfactory for flow into fan inlets of inlet boxes).

d dmax
Figure 3 — Ideal fan connections
5 Definitions of system effect factor (SEF)
5.1 Inlet SEF

With a component at the fan inlet, the SEF is defined as the relative airflow drop Δq /q along a given

v1 v1

system line as shown in Figure 4. In this figure, the solid curve and the dotted line curve are the static

pressure curves without and with system effect, respectively. The curve with system effect is obtained

by adding the pressure loss of the fitting for each flow rate increment, when it may be measured or

estimated from guidebooks (e.g. IDEL'CIK), to the static pressure of the fan + inlet fitting combination.

This procedure allows for the assessment of the installation effect related to the degradation of the fan

curve itself without accounting for the pressure loss of the fitting.
4 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)

To quantify the system effect on the whole fan curve, the quantity Δq /q is plotted versus the system

V1 V1

resistance coefficient ξ=qp/ (p being the fan static pressure at q ) in Figure 5.

fs V1
V1 fs

The SEF for a given fan + inlet fitting configuration is the average of Δq /q over the ξ range, presented

V1 V1

as a percentage in the results. Δq /q is positive when the flow with the inlet fitting is lower than that

V1 V1
of the free inlet configuration.
Key
q volume flow rate of the fan
p fan pressure
1 fan curve without system effect
2 fan curve with system effect
3 system line
Figure 4 — Definition of q and Δq on a given system line
V1 V1
1) q is either in cfm or m³/s while p is either in in. wg or Pa.
V1 fs
© ISO 2020 – All rights reserved 5
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ISO/TR 16219:2020(E)
Key
Δq /q relative flow drop in volume flow rate of the fan
V1 V1
ξ system resistance coefficient
1 system effect curve

Figure 5 — Example of relative flow drop Δq /q versus system resistance coefficient ξ

V1 V1
Clause 6 describes various situations resulting in inlet system effects.
5.2 Outlet system effect

Outlet system effect is a measure of the pressure losses across fan outlet appurtenances such as an

outlet duct, elbow, volume control damper, duct branch or plenum, due to non-uniform outlet flow

induced by the fan and improper outlet connections.

Most fans, for applications requiring systems connected at their outlets, are tested and rated for

performance with an outlet duct 2 to 3 ‘equivalent duct diameter’ long. The outlet duct helps control the

diffusion of the outlet flow and establish a uniform velocity profile (Figure 6). In most cases, it is not

practical for the fan manufacturer to supply this duct as part of the fan, but rated performance will not

be achieved unless a comparable duct is included in system design.
6 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Key
1 centrifugal fan
2 cutoff
3 blast area
4 outlet area
5 discharge duct
6 axial fan
7 25 % effective duct length
8 50 % effective duct length
9 75 % effective duct length
10 100 % effective duct length
Figure 6 — Velocity profiles at fan outlet

The techniques documented to estimate pressure losses of a fitting such as an elbow or the published

pressure drop performance from a manufacturer of a fitting such as a damper are based upon uniform

approach velocity profiles. The pressure loss so estimated is referred to as the ‘conventional pressure

loss’ across the fitting. Unless uniform approach velocity profile is ensured, there will be additional

pressure losses across these fittings. Outlet system effect is used to estimate the actual pressure loss

across the fitting in a given installation.

Clause 7 describes various situations resulting in outlet system effects. The total outlet system effect,

p (Pa), for a given situation (fitting) is defined as:
p = p + p
SE c SEo
where
p is conventional pressure loss (Pa);
p is additional pressure loss due to non-uniform flow (Pa).
SEo
© ISO 2020 – All rights reserved 7
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ISO/TR 16219:2020(E)
p can be expressed as a function of flow by the following formula:
SEo
p = C × p
SEo fd2
where
p is dynamic pressure at fan outlet 0,5*ρ*(q /A ) ;
fd2 V1 2
q is fan airflow rate, m /s;
A is fan outlet area in m ;
C is system effect coefficient;
ρ is air density in kg/m .

The outlet system effect p at each flow rate q must be added to the design system curve to obtain

SE V1
the actual system curve (Figure 7).

The system effect coefficient C is averaged over the fan curve to obtain what is called the outlet SEF in

Clause 7.
P – P = fitting conventional pressure drop at design flow
B A
P – P = outlet system effect, p , at design flow
C B SEo
P – P = fitting conventional pressure drop at actual flow
E D
P – P = outlet system effect, p , at actual flow
F E SEo
8 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Key
q fan volume flow rate
P fan pressure
1 fan catalogue pressure-flow curve
2 actual system curve
3 system curve with fitting conventional pressure drop

4 system curve without conventional pressure drop and no allowance for system effect

5 design pressure
6 actual flow
7 design flow
Figure 7 — Modification of design system curve due to outlet system effect

In some cases the conventional pressure loss p cannot be estimated or is not relevant, like for instance

with side walls close to the impeller of a plenum fan in the example of 7.2.2.2. In this case the system

effect is due to the disturbed flow in the impeller induced by the proximity of the walls.

6 Examples of inlet SEF
6.1 Introduction

Examples of inlet system effect are taken from different dedicated research programs carried out since

the 1990s. The National Engineering Laboratory (NEL) in the UK performed an extensive experimental

study on nine different types of fans and six ductwork fittings at the fan inlet. A summary of the test

configurations and main results obtained is given in References [3] and [4]. Otherwise, several research

programs have been financially supported by ASHRAE in which the tests were performed mainly by

AMCA to quantify the SEF on:
[5]

— a backward inclined/airfoil centrifugal fan – ASHRAE Research Project 1216-RP ;

© ISO 2020 – All rights reserved 9
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ISO/TR 16219:2020(E)
[6]
— a forward curved centrifugal fan – ASHRAE Research Project 1272-RP ;
[7]
— two airfoil centrifugal plenum fans – ASHRAE Research Project 1420-TRP ;
[8]

— three sizes of propeller fans of the same series – ASHRAE Research Project 1223-RP .

Finally, a test was done more recently by AMCA on a forward curved centrifugal fan with an inlet 90°

segmented elbow at various orientations.
6.2 Axial fans
6.2.1 Experimental setups
6.2.1.1 NEL

All the tests were performed on a ductwork of D = 630 mm, where D is the duct diameter. A layout of

the test ductwork with a bend connected to the fan inlet is shown in Figure 8. The distance between the

inlet fitting and the fan is varied from 0D, as in Figure 8 to 2D.

Details of the experimental program and measurement procedure are given in Reference [4] and

private reports. The test data used in the present analysis are the performance curves of the fan alone

and fan + inlet fitting and the measured pressure losses of the fittings. All the fan curves, initially based

on total pressure, were transformed into static pressure curves by subtracting the dynamic pressure at

the fan outlet according to ISO 5801.
10 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Key
1 test fan and fitting
2 throttle
3 auxiliary boost fan
4 silencers
5 flow measurement nozzle
6 flow measurement and control section
7 outlet duct
8 inlet duct

SOURCE Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study for

FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association, FETA UK.

Figure 8 — Test rig for determination of installation effect — Fitting at fan inlet

Table 1 gives the main characteristics of the axial fans tested by NEL while Figure 9 shows views of the

fans, including centrifugal fans. Figure 10 presents sketches of the fittings that were connected to the

fan inlet (or outlet) via transition elements.
They include:

a) rectangular/circular transition, section 800 × 400 → D = 630 mm, length 950 mm;

b) short square bend 90°, section 630 × 630, curvature radius 100 mm;
c) square mitred bend 90°, section 630 × 630, with guide vanes;
d) circular five-piece segmented bend, D = 630 mm;
e) rectangular to rectangular box fitting, section 800 × 400, length 2 400 mm;
f) rectangular splitter silencer, section 800 × 400, length 1 200 mm;
g) banjo connector, section 1 260 × 630, length 1 890 mm.
© ISO 2020 – All rights reserved 11
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ISO/TR 16219:2020(E)
Table 1 — Main characteristics of the axial fans tested by NEL
Fan Fan type Blade setting Hub/tip ratio Speed
° rpm
1 tubeaxial 24 0,223 1 440
2 tubeaxial 30 0,223 1 440
3 vaneaxial 24 0,389 1 440
4 vaneaxial 32 0,389 1 440
5 tubeaxial 24 0,389 2 900
6 tubeaxial 32 0,389 2 900
NOTE All the fans have a diameter of 630 mm.

SOURCE: Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study

for FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association,

FETA UK.

SOURCE Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study for

FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association, FETA UK.

Figure 9 — Views of the NEL test fans
12 © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Key
1 short square bend 90°
2 square mitred bend 90°
3 circular five-piece segmented bend
4 rectangular/circular transition
5 rectangular splitter silencer
6 banjo connector
7 rectangular to rectangular box fitting

SOURCE Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study for

FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association, FETA UK.

Figure 10 —
...

RAPPORT ISO/TR
TECHNIQUE 16219
Première édition
2020-09
Ventilateurs — Effet système et
facteurs d’effet système
Fans — System effects and system effect factors
Numéro de référence
ISO/TR 16219:2020(F)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TR 16219:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette

publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: +41 22 749 01 11
E-mail: copyright@iso.org
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés
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ISO/TR 16219:2020(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

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

1 Domaine d'application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes, définitions et symboles .......................................................................................................................................................... 1

4 Origine des effets système des ventilateurs ............................................................................................................................. 2

5 Définitions du facteur d’effet système (SEF) ........................................................................................................................... 4

5.1 SEF à l'aspiration ................................................................................................................................................................................... 4

5.2 Effet système au refoulement ..................................................................................................................................................... 6

6 Exemples de SEF à l’aspiration............................................................................................................................................................... 9

6.1 Introduction .............................................................................................................................................................................................. 9

6.2 Ventilateurs axiaux ...........................................................................................................................................................................10

6.2.1 Installations expérimentales ..............................................................................................................................10

6.2.2 Résultats ...............................................................................................................................................................................15

6.3 Ventilateurs centrifuges et hélico-centrifuges ..........................................................................................................17

6.3.1 Installations expérimentales ..............................................................................................................................17

6.3.2 Résultats ...............................................................................................................................................................................24

7 Exemples de SEF au refoulement .....................................................................................................................................................29

7.1 Ventilateurs axiaux ...........................................................................................................................................................................29

7.1.1 Généralités .........................................................................................................................................................................29

7.1.2 Installations expérimentales ..............................................................................................................................29

7.1.3 Résultats ...............................................................................................................................................................................29

7.2 Ventilateurs centrifuges et hélico-centrifuges ..........................................................................................................31

7.2.1 Installations expérimentales ..............................................................................................................................31

7.2.2 Résultats ...............................................................................................................................................................................32

8 Réduction des effets système ...............................................................................................................................................................33

8.1 Généralités ...............................................................................................................................................................................................33

8.2 Effets à l’aspiration ...........................................................................................................................................................................33

8.2.1 Généralités .........................................................................................................................................................................33

8.2.2 Écoulement non uniforme ....................................................................................................................................34

8.2.3 Giration ou tourbillon ...............................................................................................................................................35

8.2.4 Obstruction à l’aspiration .................. ....................................................................................................................36

8.3 Effets au refoulement .....................................................................................................................................................................38

8.3.1 Généralités .........................................................................................................................................................................38

8.3.2 Longueur de conduit insuffisante ..................................................................................................................38

8.3.3 Obstacle au refoulement ........................................................................................................................................39

8.3.4 Écoulement non uniforme ....................................................................................................................................39

8.4 Exemples d’effets dus à de mauvais raccordements à l'aspiration et au refoulement ...........42

9 Conclusions .............................................................................................................................................................................................................43

Annexe A (informative) Principes de base relatifs à la représentation de la performance

des ventilateurs ..................................................................................................................................................................................................44

Annexe B (informative) Calcul du système de ventilation...........................................................................................................76

Bibliographie ...........................................................................................................................................................................................................................87

© ISO 2020 – Tous droits réservés iii
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ISO/TR 16219:2020(F)
Avant-propos

L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes

nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est

en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.

L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents

critères d'approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de

droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de

brevets reçues par l'ISO (voir www .iso .org/ brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion

de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir www .iso .org/ avant -propos.

Le présent document a été élaboré par le comité technique ISO/TC 117, Ventilateurs.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www .iso .org/ fr/ members .html.
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ISO/TR 16219:2020(F)
Introduction

L’ISO 5801 fournit des informations permettant de mesurer de manière fiable les performances des

ventilateurs soumis à des essais dans des conditions de laboratoire normalisées. Le conduit, lorsqu’il

est spécifié, garantit un profil de vitesses symétrique développé à l'aspiration du ventilateur. Il peut

également y avoir une longueur droite de conduit suffisante au refoulement du ventilateur pour assurer

une conversion efficace du profil de vitesses déformé au refoulement du ventilateur en un profil stable

et homogène mesurable à la section de mesurage.

Le présent document montre comment les composants raccordés à l'aspiration et au refoulement ont un

effet sur les performances du ventilateur. Les concepteurs du système doivent non seulement étudier la

courbe idéale de performance et la perte de pression calculée du système, mais aussi prendre en compte

les pertes aux points d'entrée et de sortie du ventilateur. Celles-ci sont décrites dans le document.

Le concept de facteur d'effet système (SEF) a été introduit dans l'industrie des ventilateurs par l'AMCA

en 1973. Depuis sa création, il est devenu largement accepté dans le monde entier. Ces dernières années,

on s'est rendu compte que le SEF dépend non seulement du type de ventilateur et de la géométrie de

raccordement, mais aussi de la conception et de la fabrication du ventilateur. Certains ventilateurs

moins efficaces peuvent parfois être moins sensibles à l'effet système induit par de mauvaises conditions

d’écoulement à l’aspiration que d'autres ventilateurs plus efficaces de même type.

Par ailleurs, l'origine de l'effet système induit par un composant raccordé à l’aspiration du ventilateur

est différente de celle due au même composant raccordé au refoulement du ventilateur. C'est pourquoi

deux définitions différentes du SEF sont proposées dans le présent document selon que l'accessoire est

placé à l'aspiration ou au refoulement du ventilateur.
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RAPPORT TECHNIQUE ISO/TR 16219:2020(F)
Ventilateurs — Effet système et facteurs d’effet système
1 Domaine d'application

Le présent document traite de la dégradation probable de la performance aéraulique des ventilateurs

soumis à essai sur circuits standards conformément à l’ISO 5801 par rapport aux performances de

ventilateurs soumis à essai dans des conditions réelles sur site. Il traite des performances d’un certain

nombre de ventilateurs et de composants génériques. Les résultats obtenus constituent des lignes

directrices et ne fournissent que des tendances, car l'effet système dépend de la géométrie exacte du

ventilateur et du composant perturbateur.

Les données présentées dans le présent document sont issues d'un vaste programme expérimental

mené il y a 20 ans par le laboratoire national britannique pour l’ingénierie (NEL), principalement sur

des ventilateurs axiaux et centrifuges. Les données sont aussi tirées de plusieurs projets de recherche

financés par l'ASHRAE, dont certains sont menés dans le laboratoire de l'AMCA à Chicago, ainsi que de

résultats publiés par des fabricants de ventilateurs individuels.
2 Références normatives
Le présent document ne contient aucune référence normative.
3 Termes, définitions et symboles
Aucun terme n’est défini dans le présent document.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp

— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/
Les symboles suivants sont utilisés:
Symbole Description Unités SI Unités I-P
2 2
A Section de sortie du ventilateur m ft
C Coefficient d’effet système (SE) (voir 5.2) Sans dimension Sans dimension
p Perte de pression conventionnelle (voir 5.2) Pa in. wg
p Pression du ventilateur Pa in. wg
Pression dynamique du ventilateur (voir
p Pa in. wg
Article 4)
p Pression statique du ventilateur Pa in. wg
p Effet système (voir 5.2) Pa in. wg
Perte de pression supplémentaire due à
p Pa in. wg
SEo
un écoulement non uniforme (voir 5.2)
q Débit-volume du ventilateur m /s cfm
S Facteur d'effet système Sans dimension Sans dimension

NOTE Les expressions “pression dynamique du ventilateur” ou “pression dynamique” sont utilisés dans

tout le présent document et sont équivalents à “pression de vitesse” utilisé dans certains pays.

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ISO/TR 16219:2020(F)
Symbole Description Unités SI Unités I-P
3 0,5
ξ Coefficient de perte de pression (voir 5.1) (m /s)/(Pa )
3 2
ρ Masse volumique de l'air kg/m lbm/ft
3 2
ρ Masse volumique de l’air normal kg/m lbm/ft
std

NOTE Les expressions “pression dynamique du ventilateur” ou “pression dynamique” sont utilisés dans

tout le présent document et sont équivalents à “pression de vitesse” utilisé dans certains pays.

4 Origine des effets système des ventilateurs

Les évaluations de performances des ventilateurs des fabricants reposent principalement sur des essais

menés en laboratoire dans des conditions idéales. Les conditions idéales font référence à des profils de

vitesses d'air uniformes et sans giration à l'aspiration et au refoulement du ventilateur, comme ceux

des bancs d’essai décrits dans l’ISO 5801 et l’AMCA 210. Dans les installations “réelles” de ventilateurs,

de telles conditions idéales peuvent ne pas se présenter en raison d'un mauvais raccordement du

ventilateur au système. Ces mauvais raccordements comprennent les obstacles à l'aspiration et au

refoulement du ventilateur qui modifient les caractéristiques aérodynamiques du ventilateur et

entraînent des baisses de performances par rapport aux valeurs nominales du catalogue, même lorsque

les pertes de pression du système ont été estimées avec précision. Le terme “effet système” est une

mesure de cette dégradation des performances du ventilateur.

L'origine de l'effet système est différente à l’aspiration du ventilateur et à son refoulement. Au refoulement

du ventilateur, par exemple en cas de mauvais raccordement d’un composant au refoulement comme le

raccordement d’un coude, d’un registre ou d’un conduit secondaire, l'effet système est lié à des profils

d'écoulement non uniformes non optimaux induits par le ventilateur à l'entrée du composant (Figure 1).

Cet écoulement dégradé crée une perte de pression dans le composant, supérieure à celle qui serait

mesurée en supposant des profils d'écoulement homogènes et uniformes ou si cette perte de pression

[14]

était estimée à partir de la littérature standard telle que l’ASHRAE Handbook of Fundamentals .

Lorsque le composant est placé à l'aspiration du ventilateur, par exemple un coude ou un conduit/une

boîte à l'aspiration (Figure 2), les profils de vitesses à l'entrée du composant peuvent être uniformes

et la perte de pression de celui-ci mesurée ou estimée à partir de la littérature standard, peut être

valable. Cependant, les écoulements à l'aspiration du ventilateur (ou au refoulement du composant)

peuvent être perturbés par la présence d'un tourbillon, d'un tournoiement ou d'une région contractée.

Cette condition d'écoulement non optimale à l'aspiration du ventilateur due au composant aboutit à

une réorganisation de l'écoulement à l'intérieur de la roue et par conséquent à une détérioration des

performances du ventilateur par rapport aux valeurs nominales du catalogue. La courbe du ventilateur

peut être affectée par cet obstacle perturbateur tout comme ce peut être le cas aussi, parfois mais pas

de manière systématique, pour sa courbe de puissance. Un document d’accompagnement sera rédigé

ultérieurement pour montrer l'influence des obstacles à l'aspiration sur la courbe de puissance du

ventilateur avec les mêmes configurations de ventilateurs et de composants que celles utilisées dans le

présent document.

Dans les deux cas, le débit résultant de la combinaison ventilateur-système se détériore, mais pour des

raisons physiques distinctes. Pour cette raison, deux définitions et un traitement différents de l'effet

système d’un ventilateur sont ici fournis, selon la position du composant raccordé, à l'aspiration ou au

refoulement du ventilateur. Il est également reconnu que dans certaines situations, des obstacles très

proches du refoulement du ventilateur (par exemple, des parois latérales situées à proximité d'une roue

de ventilateur centrifuge de plénum comme illustré dans la Figure 20) peuvent également détériorer

les performances du ventilateur comme le feraient des composants situés à l'aspiration du ventilateur.

2 © ISO 2020 – Tous droits réservés
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ISO/TR 16219:2020(F)
Légende
1 ventilateur axial
Figure 1 — Profils de vitesses non-uniformes au refoulement d’un ventilateur
Rotation de la roue.
Figure 2 — Tourbillon à l’aspiration du ventilateur

Le raccordement idéal d’un ventilateur serait celui qui permettrait une distribution relativement

uniforme des vitesses dans tout le plan du composant raccordé à l’aspiration du ventilateur, sans

composante giratoire perceptible comme indiqué à la Figure 3.
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ISO/TR 16219:2020(F)
a) Distribution p idéale b) Bonne distribution p
d d
c) Distribution p satisfaisante
Légende
p pression dynamique moyenne de l’écoulement du conduit

Distribution satisfaisante aussi pour l’écoulement aux aspirations des ventilateurs, mais insuffisante pour

l’écoulement dans les boîtes à l'aspiration, peut entraîner des tourbillons dans les boîtes.

Plus de 75 % des relevés de p supérieurs à p /10 (non satisfaisant pour l’écoulement à l’aspiration des

d dmax
boîtes à l’aspiration).
Figure 3 — Raccordements idéaux d’un ventilateur
5 Définitions du facteur d’effet système (SEF)
5.1 SEF à l'aspiration

Avec un composant raccordé à l’aspiration, le SEF est défini comme la chute relative du débit Δq /q

v1 v1

le long d’une courbe du système donné comme illustré à la Figure 4. Dans cette figure, la courbe pleine

et la courbe en pointillés représentent respectivement les courbes de pression statique sans et avec

effet système. La courbe avec effet système est obtenue en ajoutant la perte de pression du composant

pour chaque accroissement du débit, lorsqu’il peut être mesuré ou estimé à partir de la littérature

(par exemple, IDEL'CIK), à la pression statique de la combinaison ventilateur + composant raccordé à

l'aspiration. Cette procédure permet d'évaluer l'effet de l'installation lié à la dégradation de la courbe du

ventilateur elle-même sans tenir compte de la perte de pression du composant.
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ISO/TR 16219:2020(F)

Pour quantifier l'effet système sur l'ensemble de la courbe du ventilateur, la valeur Δq /q est reportée

V1 V1

en fonction du coefficient de résistance du système ξ=qp/ (p étant la pression statique du

V1 fs
ventilateur à q ) à la Figure 5.

Le SEF pour une configuration donnée ventilateur + composant raccordé à l'aspiration est la moyenne

de Δq /q sur l’étendue ξ, présentée en pourcentage dans les résultats. Δq /q est positive lorsque le

V1 V1 V1 V1

débit avec le composant raccordé à l’aspiration est inférieur à celui de la configuration à aspiration libre.

Légende
q débit-volume du ventilateur
p pression statique du ventilateur
1 courbe du ventilateur sans effet système
2 courbe du ventilateur avec effet système
3 tracé du système
Figure 4 — Définition de q et de Δq sur une courbe du système donnée
V1 V1
1) q est soit en cfm ou en m³/s tandis que p est soit en in. wg ou en Pa.
V1 fs
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ISO/TR 16219:2020(F)
Légende
Δq /q chute relative de l’écoulement du débit-volume dans le ventilateur
V1 V1
ξ coefficient de résistance du système
1 courbe d’effet système

Figure 5 — Exemple de chute relative de l’écoulement Δq /q en fonction du coefficient

V1 V1
de résistance du système ξ

L’Article 6 décrit différentes situations menant à des effets système à l’aspiration.

5.2 Effet système au refoulement

L'effet système au refoulement est une mesure des pertes de pression des accessoires situés au

refoulement du ventilateur tels qu'un conduit de refoulement, un coude, un registre de réglage du débit,

un conduit secondaire ou un plénum, en raison d'un écoulement au refoulement non uniforme induit

par le ventilateur et des raccordements inappropriés au refoulement.

La plupart des ventilateurs, pour les applications nécessitant des systèmes raccordés à leur sortie, sont

soumis à essai et évalués pour leur performance avec un conduit de refoulement d’une longueur égale

à 2 à 3 fois celle du “diamètre de conduit équivalent”. Le conduit de refoulement permet de contrôler

la diffusion de l’écoulement au refoulement et d'établir un profil de vitesses uniforme (Figure 6). La

plupart du temps, il n'est pas pratique pour le fabricant de ventilateur de fournir ce type de conduit avec

le ventilateur, toutefois, la performance nominale ne sera pas atteinte à moins qu’un conduit comparable

ne soit inclus dans la conception du système.
6 © ISO 2020 – Tous droits réservés
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ISO/TR 16219:2020(F)
Légende
1 ventilateur centrifuge
2 arrêt
3 section de passage d'air
4 section de sortie
5 conduit de refoulement
6 ventilateur axial
7 25 % de la longueur effective du conduit
8 50 % de la longueur effective du conduit
9 75 % de la longueur effective du conduit
10 100 % de la longueur effective du conduit
Figure 6 — Profils de vitesses au refoulement d’un ventilateur

Les techniques documentées visant à estimer les pertes de pression d'un composant tel qu'un coude ou

les performances de perte de pression données par le fabricant d'un composant, pour un registre par

exemple, sont basées sur des profils de vitesses d'amont uniformes. La perte de pression ainsi estimée

est appelée la “perte de pression conventionnelle” dans le raccord. À moins que le profil de vitesses

d'amont uniformes ne soit garanti, ces composants subissent des pertes de pression additionnelles.

L'effet système au refoulement est utilisé pour estimer la perte réelle de pression du composant pour

une installation donnée.

L’Article 7 décrit différentes situations menant à des effets système au refoulement. L'effet système

total au refoulement, p (Pa), pour une situation donnée (composant) est défini de la manière suivante:

p = p + p
SE c SEo
p est la perte de pression conventionnelle (Pa);
p est la perte de pression additionnelle due à un écoulement non uniforme (Pa).
SEo
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ISO/TR 16219:2020(F)
p peut être exprimée en fonction de l’écoulement par la formule suivante:
SEo
p = C × p
SEo fd2
p est la pression dynamique au refoulement du ventilateur 0,5*ρ*(q /A ) ;
fd2 V1 2
q est le débit du ventilateur, m /s;
A A est la section de sortie du ventilateur, en m ;
C est le coefficient d'effet système;
ρ est la masse volumique de l’air en kg/m .

L’effet système au refoulement p à chaque débit q doit être ajouté à la courbe du système de

SE V1
conception pour obtenir la courbe réelle du système (Figure 7).

Le coefficient d'effet système C est moyenné tout au long de la courbe du ventilateur pour obtenir ce que

l’on a appelé à l’Article 7 le SEF au refoulement.
P – P = perte de pression conventionnelle du composant au débit de conception
B A
P – P = effet système au refoulement, p , au débit de conception de conception
C B SEo
P – P = perte de pression conventionnelle du composant au débit réel
E D
P – P = effet système au refoulement, p , au débit réel
F E SEo
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ISO/TR 16219:2020(F)
Légende
q débit-volume du ventilateur
P pression du ventilateur
1 courbe débit-pression catalogue du ventilateur
2 courbe de perte de pression réelle du système
3 courbe du système avec perte de pression conventionnelle du composant

4 courbe du système sans perte de pression conventionnelle du composant et sans calcul d’effet système

5 pression de conception
6 débit réel
7 débit de conception

Figure 7 — Modification de la courbe de perte de pression du système en raison de l’effet

système au refoulement

Dans certains cas, la perte de pression conventionnelle p ne peut pas être estimée ou n'est pas

pertinente, comme par exemple avec des parois latérales situées à proximité de la roue d'un ventilateur

centrifuge de plénum dans l'exemple donné en 7.2.2.2. Dans ce cas, l'effet système est dû à la perturbation

de l’écoulement dans la roue induite par la proximité des parois.
6 Exemples de SEF à l’aspiration
6.1 Introduction

Des exemples d'effets système à l'aspiration sont tirés de différents programmes de recherche dédiés

menés depuis les années 1990. Le laboratoire national britannique pour l’ingénierie (NEL) au Royaume-

Uni a réalisé une étude expérimentale approfondie sur neuf types de ventilateurs et six composants

raccordés à l'aspiration du ventilateur. Un résumé des configurations d’essai et des principaux résultats

obtenus est donné dans les références bibliographiques [3] et [4]. Par ailleurs, plusieurs programmes de

© ISO 2020 – Tous droits réservés 9
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ISO/TR 16219:2020(F)

recherche ont été financés par l'ASHRAE, avec des essais réalisés dans leur majorité par l'AMCA, pour

quantifier le SEF pour:
[5]

— un ventilateur centrifuge à pales inclinées vers l'arrière - projet de recherche ASHRAE 1216-RP ;

[6]
— un ventilateur centrifuge à pales courbées vers l'avant - projet de recherc
...

TECHNICAL ISO/TR
REPORT 16219
First edition
Fans — System effects and system
effect factors
Ventilateurs — Effet système et facteurs d’effet système
PROOF/ÉPREUVE
Reference number
ISO/TR 16219:2020(E)
ISO 2020
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ISO/TR 16219:2020(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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Contents Page

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

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

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

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

3 Terms, definitions and symbols ............................................................................................................................................................ 1

4 Origin of fan system effects ....................................................................................................................................................................... 2

5 Definitions of system effect factor (SEF) ...................................................................................................................................... 4

5.1 Inlet SEF ........................................................................................................................................................................................................ 4

5.2 Outlet system effect ............................................................................................................................................................................ 6

6 Examples of inlet SEF ....................................................................................................................................................................................... 9

6.1 Introduction .............................................................................................................................................................................................. 9

6.2 Axial fans ...................................................................................................................................................................................................10

6.2.1 Experimental setups ..................................................................................................................................................10

6.2.2 Results ....................................................................................................................................................................................15

6.3 Centrifugal and mixed-flow fans ...........................................................................................................................................17

6.3.1 Experimental setups ..................................................................................................................................................17

6.3.2 Results ....................................................................................................................................................................................24

7 Examples of outlet SEF ................................................................................................................................................................................30

7.1 Axial fans ...................................................................................................................................................................................................30

7.1.1 General...................................................................................................................................................................................30

7.1.2 Experimental setups ..................................................................................................................................................30

7.1.3 Results ....................................................................................................................................................................................30

7.2 Centrifugal and mixed-flow fans ...........................................................................................................................................32

7.2.1 Experimental setups ..................................................................................................................................................32

7.2.2 Results ....................................................................................................................................................................................33

8 Reducing system effects .............................................................................................................................................................................34

8.1 General ........................................................................................................................................................................................................34

8.2 Inlet effects ..............................................................................................................................................................................................34

8.2.1 General...................................................................................................................................................................................34

8.2.2 Non-uniform flow ...................................................................... ...................................................................................35

8.2.3 Swirl or vorticity ...........................................................................................................................................................36

8.2.4 Inlet blockage .................. .................................................... .............................................................................................36

8.3 Outlet effects ..........................................................................................................................................................................................39

8.3.1 General...................................................................................................................................................................................39

8.3.2 Insufficient duct length ...........................................................................................................................................39

8.3.3 Outlet obstruction ...................................................................... ..................................................................................40

8.3.4 Non-uniform flow ...................................................................... ...................................................................................40

8.4 Examples of the effects of poor inlet and outlet connections ......................................................................43

9 Conclusions .............................................................................................................................................................................................................44

Annex A (informative) Basic principles on fan performance representation ........................................................45

Annex B (informative) Fan system calculation ........................................................................................................................................73

Bibliography .............................................................................................................................................................................................................................83

© ISO 2020 – All rights reserved PROOF/ÉPREUVE iii
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ISO/TR 16219:2020(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 117, Fans.

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 PROOF/ÉPREUVE © ISO 2020 – All rights reserved
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ISO/TR 16219:2020(E)
Introduction

ISO 5801 provides the information for accurately measuring the performance of fans when tested

under standardised laboratory conditions. The ducting where specified ensures a fully developed

symmetrical velocity profile at the fan inlet. There may also be sufficient straight ducting at the fan

outlet to ensure efficient conversion of the distorted velocity profile at the fan outlet to a measurable

stable and homogeneous profile at the measuring station.

This document shows how fan performance is affected by both inlet and outlet connections to it.

System designers must not only look at the ideal performance curve and calculated system pressure

drop but also take into account the losses at the entry and exit points of the fan. These are described in

the document.

The concept of the system effect factor (SEF) was introduced to the fan industry by AMCA in 1973.

Since its inception it has become widely accepted worldwide. In more recent years it has been realized

that the SEF depends not only on the fan type and the fitting geometry but also on the fan design and

manufacturing. Some less efficient fans may sometimes be less sensitive to system effect induced by

poor inlet flow conditions than more efficient fans of the same type.

Furthermore, the origin of the system effect induced by a fitting at the fan inlet is different from the

one due to the same fitting located on the fan outlet. That is why two different definitions of SEF are

proposed in this document according to whether the appurtenance is at the fan inlet or fan discharge.

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TECHNICAL REPORT ISO/TR 16219:2020(E)
Fans — System effects and system effect factors
1 Scope

This document deals with the likely degradation of air performance of fans tested in standardized

airways in accordance with ISO 5801 when compared with the performance of fans tested under actual

site conditions. It deals with the performance of a number of generic types of fan and fittings. The

results given are intended as guidelines and only provide trends, as the system effect depends on the

exact geometry of the fan and disturbing component.

The test data presented in this document are taken from an extensive experimental program conducted

20 years ago by NEL (National Engineering Laboratory, UK), mainly on axial and centrifugal fans.

Data are also taken from several research projects financially supported by ASHRAE, some of them

being carried out in the AMCA laboratory in Chicago, as well as from results published previously by

individual fan manufacturers.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and symbols
No terms and definitions are listed in this document.

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/
The following symbols are used:
Symbol Description SI units I-P units
2 2
A Fan outlet area m ft
C System effect (SE) coefficient (see 5.2) Dimensionless Dimensionless
p Conventional pressure loss (see 5.2) Pa in. wg
p Fan pressure Pa in. wg
p Fan dynamic pressure (see Clause 4) Pa in. wg
p Fan static pressure Pa in. wg
p System effect (see 5.2) Pa in. wg
Additional pressure loss due to non-uni-
p Pa in. wg
SEo
form flow (see 5.2)
q Volume flow rate of the fan m /s cfm
S System effect factor Dimensionless Dimensionless
3 0,5
ξ Loss coefficient (see 5.1) (m /s)/(Pa )
3 2
ρ Density of air kg/m lbm/ft
3 2
ρ Standard air density kg/m lbm/ft
std

NOTE The term “fan dynamic pressure” or “dynamic pressure” is used throughout this document and is

equivalent to the term “velocity pressure” as used in some countries.
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ISO/TR 16219:2020(E)
4 Origin of fan system effects

Manufacturers’ fan performance ratings are mostly based on tests carried out in a laboratory under

ideal conditions. Ideal conditions refer to uniform, swirl-free air velocity profiles at fan inlet and outlet,

like those of the test rigs described in ISO 5801 and AMCA 210. In ‘real life’ fan installations, such ideal

conditions may not be present due to improper connection of the fan to the system. Such improper

connections include obstacles at fan inlets and outlets that alter the aerodynamic characteristics of the

fan and lead to deficient performance in relation to catalogue ratings, even when the system pressure

losses have been estimated accurately. The term “system effect” is a measure of this degradation of fan

performance.

The origin of system effect is different at fan outlet and at fan inlet. At the fan outlet, for example in

the case of an improperly connected outlet fitting such as an elbow, damper or duct branch, the system

effect is linked to less-than-optimum non-uniform flow profiles induced by the fan at the entrance to

the fitting (Figure 1). This degraded flow will create more pressure loss across the fitting than would

be the case when measuring the fitting loss assuming uniform homogeneous flow profiles or when

[14]

estimating it from standard handbooks such as the ASHRAE Handbook of Fundamentals .

When the fitting is at the fan inlet, for example an elbow or a fan inlet duct/box (Figure 2), the velocity

profiles at the inlet to the fitting may be uniform and the fitting pressure loss as measured or estimated

from standard handbooks may be valid. However, the flow patterns at the fan inlet (or fitting outlet)

may be disturbed with the presence of a vortex, spin or vena-contracta. This less than optimum flow

condition at fan inlet caused by the fitting will lead to a reorganization of the flow inside the impeller

and therefore a deterioration of fan performance in relation to catalogue ratings. Not only the fan curve

may be affected by this disturbing obstacle but also sometimes, but not always, the fan power curve. A

companion document will be drafted at a later date to show the influence of the inlet obstacles on the

fan power curve for the same configurations of fans and fittings as in this document.

In both cases, the resulting air flow of the fan-system combination deteriorates, but for distinct

physical reasons. For this reason, two different definitions and treatment of fan system effect are

incorporated, depending on whether the fitting is at the fan inlet or fan outlet. It is also recognized

that in some situations, obstacles very close to fan discharge (e.g. side walls at a short distance of a

plenum fan impeller as shown in Figure 20) may also deteriorate fan performance in the same manner

as components located at fan inlet.
Key
1 axial fan
Figure 1 — Non-uniform velocity profiles at fan outlet
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ISO/TR 16219:2020(E)
Impeller rotation.
Figure 2 — Vortex at fan inlet

An ideal connection to a fan would be one which results in a velocity distribution across the fan inlet

connection plane which is relatively uniformly distributed and without appreciable swirl component,

as shown in Figure 3.
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ISO/TR 16219:2020(E)
a) Ideal p distribution b) Good p distribution
d d
c) Satisfactory p distribution
Key
p mean dynamic pressure of the duct flow

Also satisfactory for flow into fan inlets, but may be unsatisfactory for flow into inlet boxes, may produce swirl

in boxes.

More than 75 % of p readings greater than p /10 (unsatisfactory for flow into fan inlets of inlet boxes).

d dmax
Figure 3 — Ideal fan connections
5 Definitions of system effect factor (SEF)
5.1 Inlet SEF

With a component at the fan inlet, the SEF is defined as the relative airflow drop Δq /q along a given

v1 v1

system line as shown in Figure 4. In this figure, the solid curve and the dotted line curve are the static

pressure curves without and with system effect, respectively. The curve with system effect is obtained

by adding the pressure loss of the fitting for each flow rate increment, when it may be measured or

estimated from guidebooks (e.g. IDEL'CIK), to the static pressure of the fan + inlet fitting combination.

This procedure allows for the assessment of the installation effect related to the degradation of the fan

curve itself without accounting for the pressure loss of the fitting.
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ISO/TR 16219:2020(E)

To quantify the system effect on the whole fan curve, the quantity Δq /q is plotted versus the system

V1 V1

resistance coefficient ξ=qp/ (p being the fan static pressure at q ) in Figure 5.

fs V1
V1 fs

The SEF for a given fan + inlet fitting configuration is the average of Δq /q over the ξ range, presented

V1 V1

as a percentage in the results. Δq /q is positive when the flow with the inlet fitting is lower than that

V1 V1
of the free inlet configuration.
Key
q volume flow rate of the fan
p fan pressure
1 fan curve without system effect
2 fan curve with system effect
3 system line
Figure 4 — Definition of q and Δq on a given system line
V1 V1
1) q is either in cfm or m³/s while p is either in in. wg or Pa.
V1 fs
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ISO/TR 16219:2020(E)
Key
Δq /q relative flow drop in volume flow rate of the fan
V1 V1
ξ system resistance coefficient
1 system effect curve

Figure 5 — Example of relative flow drop Δq /q versus system resistance coefficient ξ

V1 V1
Clause 6 describes various situations resulting in inlet system effects.
5.2 Outlet system effect

Outlet system effect is a measure of the pressure losses across fan outlet appurtenances such as an

outlet duct, elbow, volume control damper, duct branch or plenum, due to non-uniform outlet flow

induced by the fan and improper outlet connections.

Most fans, for applications requiring systems connected at their outlets, are tested and rated for

performance with an outlet duct 2 to 3 ‘equivalent duct diameter’ long. The outlet duct helps control the

diffusion of the outlet flow and establish a uniform velocity profile (Figure 6). In most cases, it is not

practical for the fan manufacturer to supply this duct as part of the fan, but rated performance will not

be achieved unless a comparable duct is included in system design.
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ISO/TR 16219:2020(E)
Key
1 centrifugal fan
2 cutoff
3 blast area
4 outlet area
5 discharge duct
6 axial fan
7 25 % effective duct length
8 50 % effective duct length
9 75 % effective duct length
10 100 % effective duct length
Figure 6 — Velocity profiles at fan outlet

The techniques documented to estimate pressure losses of a fitting such as an elbow or the published

pressure drop performance from a manufacturer of a fitting such as a damper are based upon uniform

approach velocity profiles. The pressure loss so estimated is referred to as the ‘conventional pressure

loss’ across the fitting. Unless uniform approach velocity profile is ensured, there will be additional

pressure losses across these fittings. Outlet system effect is used to estimate the actual pressure loss

across the fitting in a given installation.

Clause 7 describes various situations resulting in outlet system effects. The total outlet system effect,

p (Pa), for a given situation (fitting) is defined as:
p = p + p
SE c SEo
where
p is conventional pressure loss (Pa);
p is additional pressure loss due to non-uniform flow (Pa).
SEo
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ISO/TR 16219:2020(E)
p can be expressed as a function of flow by the following formula:
SEo
p = C × p
SEo fd2
where
p is dynamic pressure at fan outlet 0,5*ρ*(q /A ) ;
fd2 V1 2
q is fan airflow rate, m /s;
A is fan outlet area in m ;
C is system effect coefficient;
ρ is air density in kg/m .

The outlet system effect p at each flow rate q must be added to the design system curve to obtain

SE V1
the actual system curve (Figure 7).

The system effect coefficient C is averaged over the fan curve to obtain what is called the outlet SEF in

Clause 7.
P – P = fitting conventional pressure drop at design flow
B A
P – P = outlet system effect, p , at design flow
C B SEo
P – P = fitting conventional pressure drop at actual flow
E D
P – P = outlet system effect, p , at actual flow
F E SEo
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ISO/TR 16219:2020(E)
Key
q fan volume flow rate
P fan pressure
1 fan catalogue pressure-flow curve
2 actual system curve
3 system curve with fitting conventional pressure drop

4 system curve without conventional pressure drop and no allowance for system effect

5 design pressure
6 actual flow
7 design flow
Figure 7 — Modification of design system curve due to outlet system effect

In some cases the conventional pressure loss p cannot be estimated or is not relevant, like for instance

with side walls close to the impeller of a plenum fan in the example of 7.2.2.2. In this case the system

effect is due to the disturbed flow in the impeller induced by the proximity of the walls.

6 Examples of inlet SEF
6.1 Introduction

Examples of inlet system effect are taken from different dedicated research programs carried out since

the 1990s. The National Engineering Laboratory (NEL) in the UK performed an extensive experimental

study on nine different types of fans and six ductwork fittings at the fan inlet. A summary of the test

configurations and main results obtained is given in References [3] and [4]. Otherwise, several research

programs have been financially supported by ASHRAE in which the tests were performed mainly by

AMCA to quantify the SEF on:
[5]

— a backward inclined/airfoil centrifugal fan – ASHRAE Research Project 1216-RP ;

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ISO/TR 16219:2020(E)
[6]
— a forward curved centrifugal fan – ASHRAE Research Project 1272-RP ;
[7]
— two airfoil centrifugal plenum fans – ASHRAE Research Project 1420-TRP ;
[8]

— three sizes of propeller fans of the same series – ASHRAE Research Project 1223-RP .

Finally, a test was done more recently by AMCA on a forward curved centrifugal fan with an inlet 90°

segmented elbow at various orientations.
6.2 Axial fans
6.2.1 Experimental setups
6.2.1.1 NEL

All the tests were performed on a ductwork of D = 630 mm, where D is the duct diameter. A layout of

the test ductwork with a bend connected to the fan inlet is shown in Figure 8. The distance between the

inlet fitting and the fan is varied from 0D, as in Figure 8 to 2D.

Details of the experimental program and measurement procedure are given in Reference [4] and

private reports. The test data used in the present analysis are the performance curves of the fan alone

and fan + inlet fitting and the measured pressure losses of the fittings. All the fan curves, initially based

on total pressure, were transformed into static pressure curves by subtracting the dynamic pressure at

the fan outlet according to ISO 5801.
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ISO/TR 16219:2020(E)
Key
1 test fan and fitting
2 throttle
3 auxiliary boost fan
4 silencers
5 flow measurement nozzle
6 flow measurement and control section
7 outlet duct
8 inlet duct

SOURCE Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study for

FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association, FETA UK.

Figure 8 — Test rig for determination of installation effect — Fitting at fan inlet

Table 1 gives the main characteristics of the axial fans tested by NEL while Figure 9 shows views of the

fans, including centrifugal fans. Figure 10 presents sketches of the fittings that were connected to the

fan inlet (or outlet) via transition elements.
They include:

a) rectangular/circular transition, section 800 × 400 → D = 630 mm, length 950 mm;

b) short square bend 90°, section 630 × 630, curvature radius 100 mm;
c) square mitred bend 90°, section 630 × 630, with guide vanes;
d) circular five-piece segmented bend, D = 630 mm;
e) rectangular to rectangular box fitting, section 800 × 400, length 2 400 mm;
f) rectangular splitter silencer, section 800 × 400, length 1 200 mm;
g) banjo connector, section 1 260 × 630, length 1 890 mm.
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ISO/TR 16219:2020(E)
Table 1 — Main characteristics of the axial fans tested by NEL
Fan Fan type Blade setting Hub/tip ratio Speed
° rpm
1 tubeaxial 24 0,223 1 440
2 tubeaxial 30 0,223 1 440
3 vaneaxial 24 0,389 1 440
4 vaneaxial 32 0,389 1 440
5 tubeaxial 24 0,389 2 900
6 tubeaxial 32 0,389 2 900
NOTE All the fans have a diameter of 630 mm.

SOURCE: Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study

for FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association,

FETA UK.

SOURCE Based on content from National Engineering Laboratory (NEL) Fan Connected Ductwork Study for

FETA (FET001) February 1992, reproduced with permission from the Fan Manufacturers Association, FETA UK.

Figure 9 — Views of the NEL test fans
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ISO/TR 16219:2020(E)
Key
1 short square bend 90°
2 square mitred bend 90°
3 circular five-piece segmented bend
4 rectangular/circular transition
5 rectangular splitter silencer
6 banjo connector
7 rectangular to rectangular box fitting
SOURC
...

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