Ventilation for buildings - Performance testing of components/products for residential ventilation - Part 5: Cowls, assisted cowls and roof outlet terminal devices

This document specifies methods for measuring the aerodynamic and acoustic characteristics of cowls and roof outlets used in both natural and mechanical ventilation. Only those cowls and roof outlets fitted onto ducts which project above the roof surface are covered by the present standard.
Regarding the assisted cowls, only the fan assisted cowls are covered by the present standard, other types (such as injection assisted cowls) being too recent to be adequately considered for the time being.
The performance testing of the "assistance" provided by the auxiliary fan of an assisted cowl is excluded for the scope of this standard.

Lüftung von Gebäuden - Leistungsprüfung von Bauteilen/Produkten für die Lüftung von Wohnungen - Teil 5: Hauben und Dach-Fortluftdurchlässe

Diese Europäische Norm legt die Verfahren für die Messung der aerodynamischen und akustischen Kenngrößen von Hauben, Hauben mit Unterstützung und Dach-Fortluftdurchlässen fest, die in Anlagen für die natürliche und Hybridlüftung verwendet werden.
Nur Hauben, Hauben mit Unterstützung und Dach-Fortluftdurchlässe, die sowohl bei natürlicher als auch Hybridlüftung genutzt werden und die auf Luftleitungen eingebaut sind, die über die Dachoberfläche hinausragen, werden von diesem Dokument abgedeckt.
Von den Hauben mit Unterstützung sind hier nur ventilatorgestützte Hauben behandelt, da andere Arten (wie zum Beispiel Hauben mit Einblasunterstützung) noch zu neu sind, um auf angemessene Art berücksichtigt zu werden.
Dieses Dokument gilt nicht für Dach-Abluftgebläse, die nach EN 13141-4 geprüft werden.

Ventilation des bâtiments - Essais de performance des composants/produits pour la ventilation des logements - Partie 5 : Extracteurs statiques, extracteurs statiques assistés et dispositifs de sortie en toiture

Le présent document spécifie des méthodes pour mesurer les caractéristiques aérauliques et
acoustiques des extracteurs statiques, des extracteurs statiques motorisés et des dispositifs de sortie en
toiture utilisés en ventilation naturelle et en ventilation hybride.
Seuls les extracteurs statiques, les extracteurs statiques motorisés et les dispositifs de sorties en toiture
utilisés en ventilation naturelle et en ventilation hybride, et installés sur des conduits qui dépassent la
surface du toit sont couverts par le présent document.
En ce qui concerne les extracteurs statiques motorisés, seuls les extracteurs statiques motorisés
assistés d’un ventilateur sont couverts par le présent document, les autres catégories (par exemple,
extracteurs statiques motorisés à injection) sont trop récentes pour être valablement prises en compte
à ce jour.
Le présent document ne s’applique pas aux ventilateurs de rejet de toiture qui sont soumis à essai selon
l’EN 13141‐4.

Prezračevanje stavb - Preskušanje lastnosti sestavnih delov/izdelkov za prezračevanje stanovanjskih stavb - 5. del: Prezračevalne kape in odvodniki na strehah

General Information

Status
Published
Public Enquiry End Date
03-Jul-2019
Publication Date
06-Dec-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
06-Nov-2020
Due Date
11-Jan-2021
Completion Date
07-Dec-2020

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Standards Content (sample)

SLOVENSKI STANDARD
SIST EN 13141-5:2021
01-januar-2021
Nadomešča:
SIST EN 13141-5:2005
Prezračevanje stavb - Preskušanje lastnosti sestavnih delov/izdelkov za
prezračevanje stanovanjskih stavb - 5. del: Prezračevalne kape in odvodniki na
strehah

Ventilation for buildings - Performance testing of components/products for residential

ventilation - Part 5: Cowls, assisted cowls and roof outlet terminal devices

Lüftung von Gebäuden - Leistungsprüfung von Bauteilen/Produkten für die Lüftung von

Wohnungen - Teil 5: Hauben und Dach-Fortluftdurchlässe

Ventilation des bâtiments - Essais de performance des composants/produits pour la

ventilation des logements - Partie 5 : Extracteurs statiques, extracteurs statiques

assistés et dispositifs de sortie en toiture
Ta slovenski standard je istoveten z: EN 13141-5:2020
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
SIST EN 13141-5:2021 en,fr,de

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

---------------------- Page: 1 ----------------------
SIST EN 13141-5:2021
---------------------- Page: 2 ----------------------
SIST EN 13141-5:2021
EN 13141-5
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2020
EUROPÄISCHE NORM
ICS 91.140.30 Supersedes EN 13141-5:2004
English Version
Ventilation for buildings - Performance testing of
components/products for residential ventilation - Part 5:
Cowls, assisted cowls and roof outlet terminal devices

Ventilation des bâtiments - Essais de performance des Lüftung von Gebäuden - Leistungsprüfung von

composants/produits pour la ventilation des Bauteilen/Produkten für die Lüftung von Wohnungen -

logements - Partie 5 : Extracteurs statiques, extracteurs Teil 5: Hauben und Dach-Fortluftdurchlässe

statiques assistés et dispositifs de sortie en toiture
This European Standard was approved by CEN on 8 June 2020.

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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13141-5:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Contents Page

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

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 7

2 Normative references .................................................................................................................................... 7

3 Terms and definitions ................................................................................................................................... 7

4 Symbols and abbreviated terms ................................................................................................................ 8

5 Performance testing of aerodynamic characteristics ..................................................................... 10

5.1 Test installation ............................................................................................................................................ 10

5.2 Pressure drop ................................................................................................................................................ 14

5.3 Suction effect of a cowl ............................................................................................................................... 16

6 Performance testing of electrical characteristics............................................................................. 20

6.1 Test installation ............................................................................................................................................ 20

6.2 Electrical power input ................................................................................................................................ 20

7 Performance testing of acoustic characteristics of assisted cowl .............................................. 21

7.1 General ............................................................................................................................................................. 21

7.2 Radiative sound power in outdoor space – L ................................................................................ 21

7.3 Sound power level in duct connections of the unit .......................................................................... 24

8 Test report ...................................................................................................................................................... 25

8.1 General ............................................................................................................................................................. 25

8.2 Aerodynamics characteristics ................................................................................................................. 26

8.3 Electricals characteristics ......................................................................................................................... 26

8.4 Acoustics characteristics ........................................................................................................................... 26

Annex A (normative) Derivation of values through the similitude law................................................. 28

Bibliography ................................................................................................................................................................. 29

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
European foreword

This document (EN 13141-5:2020) has been prepared by 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 April 2021, and conflicting national standards shall be

withdrawn at the latest by April 2021.

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 13141-5:2004.

In addition to a number of editorial revisions, the following main changes have been made with respect

to EN 13141-5:2004:
— modification of the title and scope to add assisted cowls;

— exclusion from the scope of roof exhaust fans which are tested according to EN 13141-4;

— reorganization of the clause concerning the performance testing of aerodynamic characteristics

(now Clause 5) in order to have a more homogeneous organization and modification of all the figures

to make them more understandable;

— modification of the subclause concerning test installation for aerodynamic characteristics (now 5.1),

which includes the modification of all tests installation requirements as well as the distinction

between requirements that apply to all the tests and those that apply only to the wind tunnel use;

— modification of the volume flow rate correction (see 5.2 concerning pressure drop);

— modification of the formula used to characterize the suction effect of a cowl (see 5.3.2 concerning the

measurements and calculations);

— renaming of “Preliminary test” as “Least favourable horizontal wind approach angle for the suction

effect” (see 5.3.3.1);

— replacement of “a wind of sufficient speed to give easily measurable pressure differences” by “a wind

of 8 m/s” (see 5.3.3.1);

— removal of the two following measurements points: V = 0,5 m/s and 1,5 m/s (see 5.3.3.2);

— more precise definition of the three series of measurements to carry out (i.e. v = 0m/s,

duct
v = 4m/s and 0 m/s < v < 4 m/s) (see 5.3.3.3);
duct duct

— for additional testing (e.g. acoustics and aerodynamic) for fan assisted cowls, reference to

EN 13141-4 is replaced by reference to EN ISO 5801 and more developed information are given;

— addition of a test method for measuring the combined effect of natural wind and wind from the fan

assisted cowl;
— addition of a detailed clause concerning the test report;

— review of the entire document in order to make it more accessible regarding the changes made.

---------------------- Page: 5 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)

A list of all parts in the EN 13141 series, published under the general title Ventilation for buildings —

Performance testing of components/products for residential ventilation can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Introduction

The position of this document in the field of standards for the mechanical building services is shown in

Figure 1.
Mechanical Building Services
Ventilation and air conditioning
Control systems Heating systems
systems
Mechanical and Design criteria for
Air terminal Air handling System
Ductwork natural residential the indoor Installation
devices units performance
ventilation environment
Components/product
s for residential Performance testing of Design and Performance testing
Simplified calculation
ventilation Required components/products dimensioning for and installation
methods for residential
and optional for residential residential ventilation checks for residential
ventilation systems
performance ventilation systems ventilation systems
characteristics
Part 1: Externally and internally mounted air transfer devices
Part 2: Exhaust and supply air terminal devices
Part 3: Range hoods for residential use without fan
Part 4: Fans used in residential ventilation systems
Part 5: Cowls, assisted cowls and roof outlet terminal devices
Part 6: Exhaust ventilation system packages used in a single dwelling
Part 7: Performance testing of a mechanical supply and exhaust
ventilation units (including heat recovery) for mechanical ventilation
systems intended for single family dwellings
---------------------- Page: 7 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Part 8: Performance testing of un-ducted mechanical supply and exhaust
ventilation units (including heat recovery) for mechanical ventilation
systems intended for a single room
Part 9: Externally mounted humidity controlled air transfer device
Part 10: Humidity controlled extract air terminal device
Part 11: Supply ventilation units

Figure 1 — Position of EN 13141-5 in the field of the mechanical building services

---------------------- Page: 8 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
1 Scope
This document specifies methods for measuring:
— the aerodynamic characteristics of cowls, fan assisted cowls and roof outlets;
— the electrical and acoustic characteristics of fan assisted cowls.

This document is applicable to cowls, assisted cowls and roof outlets used in natural, hybrid or

mechanical ventilation and that are meant to be fitted onto ducts which project above the roof surface.

This document does not apply to:

— assisted cowls assisted by a device other than a fan (e.g. injection assisted cowls);

— roof exhaust fans (see EN 13141-4).
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.

EN 12792, Ventilation for buildings — Symbols, terminology and graphical symbols

EN ISO 5136, Acoustics — Determination of sound power radiated into a duct by fans and other air-moving

devices — In-duct method (ISO 5136)

EN ISO 5801:2017, Fans — Performance testing using standardized airways (ISO 5801:2017)

EN ISO 7235, Acoustics — Laboratory measurement procedures for ducted silencers and air-terminal

units — Insertion loss, flow noise and total pressure loss (ISO 7235)

EN ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories

(ISO/IEC 17025:2017)

ISO 13347-2, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 2: Reverberant room method

ISO 13347-3, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 3: Enveloping surface methods

ISO 13347-4, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 4: Sound intensity method
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 12792 and the following apply.

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

• IEC Electropedia: available at http://www.electropedia.org/
• ISO online browsing platform: available at https://www.iso.org/obp
---------------------- Page: 9 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
3.1
cowl

exhaust air terminal device with or without moving component, intended to be fitted on top of a duct,

with aim, by creating negative pressure depending on the wind speed, to avoid reverse flow and to

increase the exhaust air flow rate in presence of wind

[SOURCE: EN 12792:2003, 92, modified – reformulation of the definition in a single sentence]

3.2
assisted cowl

cowl fitted with an auxiliary device using an energy source other than wind to compensate for lack of

suction effect

[SOURCE: EN 12792:2003, 46, modified – removal of “such as a fan and” and replacement of “pressure

difference” by “suction effect”]
3.3
fan assisted cowl
assisted cowl where the auxiliary device is a fan
3.4
roof outlet

exhaust air terminal device without moving component, intended to be fitted on top of a duct

4 Symbols and abbreviated terms
For the purposes of this document, the symbols listed in Table 1 apply.
No abbreviated terms are listed in this document.
Table 1 — Symbols
Symbol Quantity Unit
C(α,v ,v )
pressure factor —
tunnel duct
D duct diameter m
L duct length m
L sound power level dB
L A-weighted sound power level dB(A)
radiated sound power in the outdoor space (including casing) dB
p atmospheric pressure Pa
p dynamic pressure in the test duct Pa
d,duct
dynamic pressure in the wind tunnel Pa
d,tunnel
p static gauge pressure in the test duct Pa
s,duct
---------------------- Page: 10 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Symbol Quantity Unit
p average static gauge pressure in the wind tunnel Pa
s,tunnel
P electrical power input W
q corrected volume flow rate m /s
v,cor
measured volume flow rate m /s
v,meas
r coefficient of determination of the regression line —
v mean air speed in the test duct m/s
duct
v air speed in the wind tunnel (wind speed) m/s
tunnel
α vertical wind approach angle degree
β horizontal wind approach angle degree
∆p pressure drop Pa
∆p difference between the total pressure in the test duct Pa
cowl
approaching the cowl under test and the static pressure in the
tunnel
∆p pressure drop due to friction in the test duct between the Pa
f,duct
pressure tapping and the bottom of the cowl
ζ pressure drop coefficient —
θ temperature of the air in the test duct °C
3 3
density of 1 204 kg/m corresponding to the air under kg/m
ref
standard conditions (20 °C, 101 325 Pa)
air density in the wind tunnel kg/m
tunnel
---------------------- Page: 11 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5 Performance testing of aerodynamic characteristics
5.1 Test installation
5.1.1 General

The aerodynamic characteristics of the air terminal device shall be tested in a test installation as shown

in Figure 2. For pressure drop (see 5.2) and mechanical tests without wind (see 5.3.3.4), the wind tunnel

is not necessary. The test installation shall comprise the following:

— an adjustable air supply incorporating a flow rate measuring device with an uncertainty in

accordance with 5.1.3 (e.g. orifice plate or venturi tube conforming with EN ISO 5167-1, or other flow

meter, such as a rotameter). The air supply passes via an airtight duct;

— means to stabilize the flow and pressure upstream the test duct, e.g. airtight plenum chamber (with

a side length at least 4 times the diameter of the test duct) containing flow settling screens at the air

entry zone and a smooth outlet;

— an airtight test circular duct (test duct) to carry the air terminal device under test, of diameter D

chosen according to EN 1506:2007, Table 1 to suit the air terminal device, and with a minimum

length as given by Formula (1).
LD6⋅
(1)

In case of assisted cowl, the test installation shown in Figure 2 shall be in accordance with Category C

installation as defined in EN ISO 5801:2017, 11.5, ducted inlet and free outlet.

The test shall be performed according to the intended use of the air terminal device.

The pressure measurement point in the test duct (Figure 2, Key 6) shall be located 3D upstream of the air

terminal device (D being the diameter of the test duct).

In order to reach high pressure values, a device to increase the pressure drop in the test duct (e.g. iris)

may be used (Figure 2, Key 15). In order to reach low pressure values, a fan with flow rate adjusted device

may be used (Figure 2, Key 12).
5.1.2 Wind tunnel

Static pressure shall be measured using two pressure probes (or more) located in the working section

(see Figure 2, section A-A). The pressure probes should be situated far enough from the cowl to avoid

side effects, at each side of the wind cross section. The reference pressure is the average of the two (or

more) static pressures.

The wind speed measurement shall be made at 1 m upstream from the air terminal device and in front of

it.

During the suction effect tests, the volume flow rate in the test duct shall not exceed 2 % of the volume

flow rate from the wind tunnel.

If the tests are carried out in a confined working section as shown in Figure 2, then the cross-section area

of the working section (in projection along the axis of the wind tunnel) shall be at least 20 times the cross

section area of the cowl and duct in the wind.

If the tests are carried out using an open jet type wind tunnel, then the cross section area of the jet shall

be at least 10 times the cross-section area (in projection along the axis of the wind tunnel) of the cowl

and duct in the wind.

In order to avoid side effects from the wind tunnel, the test duct part located in the working section (see

Figure 2, section A-A) of the wind tunnel (i.e. the duct part blown by the wind) shall be at least 5 times

the duct diameter.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)

The turbulence intensity of the air inside the wind tunnel upwards from the air terminal device shall be

less than 5 %.

To simulate varying vertical wind approach angles, it shall be possible to rotate the cowl and test duct

about an axis perpendicular to the wind tunnel axis and test duct axis, the cowl remaining near the same

test point located at the wind tunnel axis to remain in the homogenous wind stream (see Figure 3).

NOTE 1 The test point represents the position of the cowl during the test.

In addition, where the test duct axis is perpendicular to the wind tunnel axis, it shall be possible to rotate

the cowl about the test duct axis to simulate varying horizontal wind approach angles (see Figure 4).

When the mounting parts which support the duct and the cowl are in the wind, they should have limited

influence from an aerodynamic point of view.

NOTE 2 No practical rules can be formulated in this document on how to limit the influence of mounting parts.

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Key
1 wind tunnel 9 plenum chamber
2 location for wind speed measurement 10 air flow measuring device
3 air terminal device 11 flow straightener

4 location for static pressure measurement 12 fan with flow rate adjusting device

5 test duct 13 air supply

6 location for static pressure measurement 14 location for static pressure measurement at the

bottom of the device
7 location of sealing for preliminary suction test 15 pressure regulation device
8 flow setting screens
Figure 2 — Typical example of a test installation
---------------------- Page: 14 ----------------------
SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Key
1 axis of wind tunnel 5 test duct
2 wind tunnel 6 axis of test duct
3 location for wind speed measurement 7 axis of rotation
4 homogeneous part of the wind flow
Figure 3 — Rotation to simulate varying vertical wind approach
Key
1 axis of wind tunnel 4 axis of test duct (axis of rotation)
2 wind tunnel 5 test duct
3 location for wind speed measurement
Figure 4 — Rotation to simulate varying horizontal wind approach
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5.1.3 Maximum permissible measurement error
The maximum permissible measurement error is given in Table 2 for each quantity.
Table 2 — Maximum permissible measurement error
Quantity Maximum permissible Unit
measurement error
Wind speed ≤ 0,05 m/s
Air flow ≤ 0,000 3 + 0,03 × measured value m /s
Pressure ≤ 0,5 + 0,03 × measured value Pa
5.2 Pressure drop
5.2.1 General

When testing a fan assisted cowl, the auxiliary fan shall be switched-off and its blades shall not be blocked.

5.2.2 Measurements and calculations
The parameters to be measured are:
— the volume flow rate in the test duct;

— the static pressure difference between the test duct (Figure 2, key 6) and the room in which the test

is carried out (static gauge pressure);
— the atmospheric pressure;
— the temperature of the air in the test duct.

The measured volume flow rate shall be corrected if the temperature or barometric pressure are different

from the standard conditions (20 °C and 101 325 Pa), using Formula (2).
0,5 0,5
   
293,15
   
qq= ⋅⋅ (2)
v,cor v,meas
 
101 325 273,15 + θ
   a 
where
q is the corrected volume flow rate, in m /s;
v,cor
q is the measured volume flow rate, in m /s;
v,meas
p is the atmospheric pressure, in Pa;
θ is the temperature of the air in the test duct, in °C.

For each measurement, the dynamic pressure in the test duct, p , shall be calculated using

d,duct
Formula (3).
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
pv⋅ ρ ⋅ (3)
d,duct ref duct
where
p is the dynamic pressure in the test duct, in Pa;
d,duct
3 3

ρ is the air density, in kg/m , in this case ρ = 1 204 kg/m which corresponds to the air

ref ref
under standard condition (20°C, 101 325 Pa);
v is the mean air speed in the test duct, in m/s.
duct
with
4 ⋅ q
v,cor
v = (4)
duct
π ⋅ D
where
q is the corrected volume flow rate, in m /s;
v,cor
D is the test duct diameter, in m.
For each measurement, the pressure drop shall be calculated using Formula (5).
p p + p (5)
s,duct d,duct
where
Δp is the pressure drop, in Pa;
p is the static gauge pressure in the test duct, in Pa;
s,duct
p is the dynamic pressure in the test duct, in Pa.
d,duct

NOTE In this calculation method of the pressure drop, it is assumed that the thermal gravity effect (stack effect

in the test duct) is negligible.
5.2.3 Test method

The test shall be carried out by varying the flow rate through the air terminal device to give static pressure

differences of 5 Pa, 10 Pa, 20 Pa and 50 Pa with a tolerance of ± 1 Pa, between the test duct and the room

in which the test is carried out.
5.2.4 Analysis of results

It shall be checked whether the pressure drop can be expressed with a single pressure drop coefficient,

ζ, as given by Formula (6).
∆=pp ζ⋅ (6)
d,duct

To that effect, a linear regression line intercepting the point (p = 0; ΔP = 0) shall be searched through

d,duct

the obtained couples (p ; Δp) using an appropriate least squares method. For the regression line and

d,duct

Formula (6) to be valid in terms of this document, the coefficient of determination (r ) of the regression

line shall be ≥ 0,98. With a valid regression line, the pressure drop coefficient, ζ, equals the slope of the

line.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5.3 Suction effect of a cowl
5.3.1 General

In use, the cowl performance will combine both the suction effect due to the wind and the pressure drop

due to the air flowing through the cowl. The tests methods described in 5.3.3.2 and 5.3.3.3 measure the

performance of the cowl when these two effects are combined.

The test method described in 5.3.3.4 is used to characterize the effect of the fan for fan assisted cowls in

the absence of wind.

In use, when the auxiliary fan of an assisted cowl is switched on, the assisted cowl performance combines

both the suction effect due to the wind and due to the fan. The test described in 5.3.3.5 characterizes the

performance of the assisted cowl when these two effects are combined.

When testing a fan assisted cowl for tests without fan, the auxiliary fan shall be switched off and its blades

shall not be blocked.

The electric supply of the assisted cowl shall respond to the manufacturer specifications.

All tests shall be performed using the same cowl as in 5.2.
5.3.2 Measurements and calculations
The following parameters shall be measured:
— wind speed;
— air flow in test duct;
— static gauge pressure in test duct (Figure 2, Key 6);
— static gauge pressure in wind tunnel (Figure 2, Key 4);
— horizontal and vertical wind approach angles (see Figure 3 and Figure 4);
— atmospheric pressure;
— air temperature in the test duct.

The dynamic pressure of the wind, p , is calculated with the air speed measured at point 2 (see

d,tunnel
Figure 2) using Formula (7).
pv⋅ ρ ⋅ (7)
d,tunnel tunnel tunnel
where
p is the dynamic pressure in the wind tunnel, in Pa;
d,tunnel
is the air density in the wind tunnel, in kg/m ;
tunnel
v is the wind speed, in m/s.
tunnel

The difference between the total pressure in the test duct approaching the cowl and the static pressure

in the wind tunnel is calculated using Formula (8).
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
∆−pp= ∆p + p − p (8)
cowl d,duct f,duct s,,duct s tunnel
where

Δp is the difference between the total pressure in the test duct approaching the cowl under

cowl
test and the static pressure in the tunnel, in Pa;
Δp is the pressure drop due to friction in th
...

SLOVENSKI STANDARD
SIST EN 13141-5:2021
01-januar-2021
Nadomešča:
SIST EN 13141-5:2005
Prezračevanje stavb - Preskušanje lastnosti sestavnih delov/izdelkov za

prezračevanje stanovanjskih stavb - 5. del: Prezračevalne kape in strešni iztoki na

strehah

Ventilation for buildings - Performance testing of components/products for residential

ventilation - Part 5: Cowls, assisted cowls and roof outlet terminal devices

Lüftung von Gebäuden - Leistungsprüfung von Bauteilen/Produkten für die Lüftung von

Wohnungen - Teil 5: Hauben und Dach-Fortluftdurchlässe

Ventilation des bâtiments - Essais de performance des composants/produits pour la

ventilation des logements - Partie 5 : Extracteurs statiques, extracteurs statiques

assistés et dispositifs de sortie en toiture
Ta slovenski standard je istoveten z: EN 13141-5:2020
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
SIST EN 13141-5:2021 en,fr,de

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

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SIST EN 13141-5:2021
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SIST EN 13141-5:2021
EN 13141-5
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2020
EUROPÄISCHE NORM
ICS 91.140.30 Supersedes EN 13141-5:2004
English Version
Ventilation for buildings - Performance testing of
components/products for residential ventilation - Part 5:
Cowls, assisted cowls and roof outlet terminal devices

Ventilation des bâtiments - Essais de performance des Lüftung von Gebäuden - Leistungsprüfung von

composants/produits pour la ventilation des Bauteilen/Produkten für die Lüftung von Wohnungen -

logements - Partie 5 : Extracteurs statiques, extracteurs Teil 5: Hauben und Dach-Fortluftdurchlässe

statiques assistés et dispositifs de sortie en toiture
This European Standard was approved by CEN on 8 June 2020.

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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13141-5:2020 E

worldwide for CEN national Members.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Contents Page

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

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 7

2 Normative references .................................................................................................................................... 7

3 Terms and definitions ................................................................................................................................... 7

4 Symbols and abbreviated terms ................................................................................................................ 8

5 Performance testing of aerodynamic characteristics ..................................................................... 10

5.1 Test installation ............................................................................................................................................ 10

5.2 Pressure drop ................................................................................................................................................ 14

5.3 Suction effect of a cowl ............................................................................................................................... 16

6 Performance testing of electrical characteristics............................................................................. 20

6.1 Test installation ............................................................................................................................................ 20

6.2 Electrical power input ................................................................................................................................ 20

7 Performance testing of acoustic characteristics of assisted cowl .............................................. 21

7.1 General ............................................................................................................................................................. 21

7.2 Radiative sound power in outdoor space – L ................................................................................ 21

7.3 Sound power level in duct connections of the unit .......................................................................... 24

8 Test report ...................................................................................................................................................... 25

8.1 General ............................................................................................................................................................. 25

8.2 Aerodynamics characteristics ................................................................................................................. 26

8.3 Electricals characteristics ......................................................................................................................... 26

8.4 Acoustics characteristics ........................................................................................................................... 26

Annex A (normative) Derivation of values through the similitude law................................................. 28

Bibliography ................................................................................................................................................................. 29

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
European foreword

This document (EN 13141-5:2020) has been prepared by 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 April 2021, and conflicting national standards shall be

withdrawn at the latest by April 2021.

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 13141-5:2004.

In addition to a number of editorial revisions, the following main changes have been made with respect

to EN 13141-5:2004:
— modification of the title and scope to add assisted cowls;

— exclusion from the scope of roof exhaust fans which are tested according to EN 13141-4;

— reorganization of the clause concerning the performance testing of aerodynamic characteristics

(now Clause 5) in order to have a more homogeneous organization and modification of all the figures

to make them more understandable;

— modification of the subclause concerning test installation for aerodynamic characteristics (now 5.1),

which includes the modification of all tests installation requirements as well as the distinction

between requirements that apply to all the tests and those that apply only to the wind tunnel use;

— modification of the volume flow rate correction (see 5.2 concerning pressure drop);

— modification of the formula used to characterize the suction effect of a cowl (see 5.3.2 concerning the

measurements and calculations);

— renaming of “Preliminary test” as “Least favourable horizontal wind approach angle for the suction

effect” (see 5.3.3.1);

— replacement of “a wind of sufficient speed to give easily measurable pressure differences” by “a wind

of 8 m/s” (see 5.3.3.1);

— removal of the two following measurements points: V = 0,5 m/s and 1,5 m/s (see 5.3.3.2);

— more precise definition of the three series of measurements to carry out (i.e. v = 0m/s,

duct
v = 4m/s and 0 m/s < v < 4 m/s) (see 5.3.3.3);
duct duct

— for additional testing (e.g. acoustics and aerodynamic) for fan assisted cowls, reference to

EN 13141-4 is replaced by reference to EN ISO 5801 and more developed information are given;

— addition of a test method for measuring the combined effect of natural wind and wind from the fan

assisted cowl;
— addition of a detailed clause concerning the test report;

— review of the entire document in order to make it more accessible regarding the changes made.

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)

A list of all parts in the EN 13141 series, published under the general title Ventilation for buildings —

Performance testing of components/products for residential ventilation can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Introduction

The position of this document in the field of standards for the mechanical building services is shown in

Figure 1.
Mechanical Building Services
Ventilation and air conditioning
Control systems Heating systems
systems
Mechanical and Design criteria for
Air terminal Air handling System
Ductwork natural residential the indoor Installation
devices units performance
ventilation environment
Components/product
s for residential Performance testing of Design and Performance testing
Simplified calculation
ventilation Required components/products dimensioning for and installation
methods for residential
and optional for residential residential ventilation checks for residential
ventilation systems
performance ventilation systems ventilation systems
characteristics
Part 1: Externally and internally mounted air transfer devices
Part 2: Exhaust and supply air terminal devices
Part 3: Range hoods for residential use without fan
Part 4: Fans used in residential ventilation systems
Part 5: Cowls, assisted cowls and roof outlet terminal devices
Part 6: Exhaust ventilation system packages used in a single dwelling
Part 7: Performance testing of a mechanical supply and exhaust
ventilation units (including heat recovery) for mechanical ventilation
systems intended for single family dwellings
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Part 8: Performance testing of un-ducted mechanical supply and exhaust
ventilation units (including heat recovery) for mechanical ventilation
systems intended for a single room
Part 9: Externally mounted humidity controlled air transfer device
Part 10: Humidity controlled extract air terminal device
Part 11: Supply ventilation units

Figure 1 — Position of EN 13141-5 in the field of the mechanical building services

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
1 Scope
This document specifies methods for measuring:
— the aerodynamic characteristics of cowls, fan assisted cowls and roof outlets;
— the electrical and acoustic characteristics of fan assisted cowls.

This document is applicable to cowls, assisted cowls and roof outlets used in natural, hybrid or

mechanical ventilation and that are meant to be fitted onto ducts which project above the roof surface.

This document does not apply to:

— assisted cowls assisted by a device other than a fan (e.g. injection assisted cowls);

— roof exhaust fans (see EN 13141-4).
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.

EN 12792, Ventilation for buildings — Symbols, terminology and graphical symbols

EN ISO 5136, Acoustics — Determination of sound power radiated into a duct by fans and other air-moving

devices — In-duct method (ISO 5136)

EN ISO 5801:2017, Fans — Performance testing using standardized airways (ISO 5801:2017)

EN ISO 7235, Acoustics — Laboratory measurement procedures for ducted silencers and air-terminal

units — Insertion loss, flow noise and total pressure loss (ISO 7235)

EN ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories

(ISO/IEC 17025:2017)

ISO 13347-2, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 2: Reverberant room method

ISO 13347-3, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 3: Enveloping surface methods

ISO 13347-4, Industrial fans — Determination of fan sound power levels under standardized laboratory

conditions — Part 4: Sound intensity method
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 12792 and the following apply.

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

• IEC Electropedia: available at http://www.electropedia.org/
• ISO online browsing platform: available at https://www.iso.org/obp
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
3.1
cowl

exhaust air terminal device with or without moving component, intended to be fitted on top of a duct,

with aim, by creating negative pressure depending on the wind speed, to avoid reverse flow and to

increase the exhaust air flow rate in presence of wind

[SOURCE: EN 12792:2003, 92, modified – reformulation of the definition in a single sentence]

3.2
assisted cowl

cowl fitted with an auxiliary device using an energy source other than wind to compensate for lack of

suction effect

[SOURCE: EN 12792:2003, 46, modified – removal of “such as a fan and” and replacement of “pressure

difference” by “suction effect”]
3.3
fan assisted cowl
assisted cowl where the auxiliary device is a fan
3.4
roof outlet

exhaust air terminal device without moving component, intended to be fitted on top of a duct

4 Symbols and abbreviated terms
For the purposes of this document, the symbols listed in Table 1 apply.
No abbreviated terms are listed in this document.
Table 1 — Symbols
Symbol Quantity Unit
C(α,v ,v )
pressure factor —
tunnel duct
D duct diameter m
L duct length m
L sound power level dB
L A-weighted sound power level dB(A)
radiated sound power in the outdoor space (including casing) dB
p atmospheric pressure Pa
p dynamic pressure in the test duct Pa
d,duct
dynamic pressure in the wind tunnel Pa
d,tunnel
p static gauge pressure in the test duct Pa
s,duct
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Symbol Quantity Unit
p average static gauge pressure in the wind tunnel Pa
s,tunnel
P electrical power input W
q corrected volume flow rate m /s
v,cor
measured volume flow rate m /s
v,meas
r coefficient of determination of the regression line —
v mean air speed in the test duct m/s
duct
v air speed in the wind tunnel (wind speed) m/s
tunnel
α vertical wind approach angle degree
β horizontal wind approach angle degree
∆p pressure drop Pa
∆p difference between the total pressure in the test duct Pa
cowl
approaching the cowl under test and the static pressure in the
tunnel
∆p pressure drop due to friction in the test duct between the Pa
f,duct
pressure tapping and the bottom of the cowl
ζ pressure drop coefficient —
θ temperature of the air in the test duct °C
3 3
density of 1 204 kg/m corresponding to the air under kg/m
ref
standard conditions (20 °C, 101 325 Pa)
air density in the wind tunnel kg/m
tunnel
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5 Performance testing of aerodynamic characteristics
5.1 Test installation
5.1.1 General

The aerodynamic characteristics of the air terminal device shall be tested in a test installation as shown

in Figure 2. For pressure drop (see 5.2) and mechanical tests without wind (see 5.3.3.4), the wind tunnel

is not necessary. The test installation shall comprise the following:

— an adjustable air supply incorporating a flow rate measuring device with an uncertainty in

accordance with 5.1.3 (e.g. orifice plate or venturi tube conforming with EN ISO 5167-1, or other flow

meter, such as a rotameter). The air supply passes via an airtight duct;

— means to stabilize the flow and pressure upstream the test duct, e.g. airtight plenum chamber (with

a side length at least 4 times the diameter of the test duct) containing flow settling screens at the air

entry zone and a smooth outlet;

— an airtight test circular duct (test duct) to carry the air terminal device under test, of diameter D

chosen according to EN 1506:2007, Table 1 to suit the air terminal device, and with a minimum

length as given by Formula (1).
LD6⋅
(1)

In case of assisted cowl, the test installation shown in Figure 2 shall be in accordance with Category C

installation as defined in EN ISO 5801:2017, 11.5, ducted inlet and free outlet.

The test shall be performed according to the intended use of the air terminal device.

The pressure measurement point in the test duct (Figure 2, Key 6) shall be located 3D upstream of the air

terminal device (D being the diameter of the test duct).

In order to reach high pressure values, a device to increase the pressure drop in the test duct (e.g. iris)

may be used (Figure 2, Key 15). In order to reach low pressure values, a fan with flow rate adjusted device

may be used (Figure 2, Key 12).
5.1.2 Wind tunnel

Static pressure shall be measured using two pressure probes (or more) located in the working section

(see Figure 2, section A-A). The pressure probes should be situated far enough from the cowl to avoid

side effects, at each side of the wind cross section. The reference pressure is the average of the two (or

more) static pressures.

The wind speed measurement shall be made at 1 m upstream from the air terminal device and in front of

it.

During the suction effect tests, the volume flow rate in the test duct shall not exceed 2 % of the volume

flow rate from the wind tunnel.

If the tests are carried out in a confined working section as shown in Figure 2, then the cross-section area

of the working section (in projection along the axis of the wind tunnel) shall be at least 20 times the cross

section area of the cowl and duct in the wind.

If the tests are carried out using an open jet type wind tunnel, then the cross section area of the jet shall

be at least 10 times the cross-section area (in projection along the axis of the wind tunnel) of the cowl

and duct in the wind.

In order to avoid side effects from the wind tunnel, the test duct part located in the working section (see

Figure 2, section A-A) of the wind tunnel (i.e. the duct part blown by the wind) shall be at least 5 times

the duct diameter.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)

The turbulence intensity of the air inside the wind tunnel upwards from the air terminal device shall be

less than 5 %.

To simulate varying vertical wind approach angles, it shall be possible to rotate the cowl and test duct

about an axis perpendicular to the wind tunnel axis and test duct axis, the cowl remaining near the same

test point located at the wind tunnel axis to remain in the homogenous wind stream (see Figure 3).

NOTE 1 The test point represents the position of the cowl during the test.

In addition, where the test duct axis is perpendicular to the wind tunnel axis, it shall be possible to rotate

the cowl about the test duct axis to simulate varying horizontal wind approach angles (see Figure 4).

When the mounting parts which support the duct and the cowl are in the wind, they should have limited

influence from an aerodynamic point of view.

NOTE 2 No practical rules can be formulated in this document on how to limit the influence of mounting parts.

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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Key
1 wind tunnel 9 plenum chamber
2 location for wind speed measurement 10 air flow measuring device
3 air terminal device 11 flow straightener

4 location for static pressure measurement 12 fan with flow rate adjusting device

5 test duct 13 air supply

6 location for static pressure measurement 14 location for static pressure measurement at the

bottom of the device
7 location of sealing for preliminary suction test 15 pressure regulation device
8 flow setting screens
Figure 2 — Typical example of a test installation
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
Key
1 axis of wind tunnel 5 test duct
2 wind tunnel 6 axis of test duct
3 location for wind speed measurement 7 axis of rotation
4 homogeneous part of the wind flow
Figure 3 — Rotation to simulate varying vertical wind approach
Key
1 axis of wind tunnel 4 axis of test duct (axis of rotation)
2 wind tunnel 5 test duct
3 location for wind speed measurement
Figure 4 — Rotation to simulate varying horizontal wind approach
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5.1.3 Maximum permissible measurement error
The maximum permissible measurement error is given in Table 2 for each quantity.
Table 2 — Maximum permissible measurement error
Quantity Maximum permissible Unit
measurement error
Wind speed ≤ 0,05 m/s
Air flow ≤ 0,000 3 + 0,03 × measured value m /s
Pressure ≤ 0,5 + 0,03 × measured value Pa
5.2 Pressure drop
5.2.1 General

When testing a fan assisted cowl, the auxiliary fan shall be switched-off and its blades shall not be blocked.

5.2.2 Measurements and calculations
The parameters to be measured are:
— the volume flow rate in the test duct;

— the static pressure difference between the test duct (Figure 2, key 6) and the room in which the test

is carried out (static gauge pressure);
— the atmospheric pressure;
— the temperature of the air in the test duct.

The measured volume flow rate shall be corrected if the temperature or barometric pressure are different

from the standard conditions (20 °C and 101 325 Pa), using Formula (2).
0,5 0,5
   
293,15
   
qq= ⋅⋅ (2)
v,cor v,meas
 
101 325 273,15 + θ
   a 
where
q is the corrected volume flow rate, in m /s;
v,cor
q is the measured volume flow rate, in m /s;
v,meas
p is the atmospheric pressure, in Pa;
θ is the temperature of the air in the test duct, in °C.

For each measurement, the dynamic pressure in the test duct, p , shall be calculated using

d,duct
Formula (3).
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
pv⋅ ρ ⋅ (3)
d,duct ref duct
where
p is the dynamic pressure in the test duct, in Pa;
d,duct
3 3

ρ is the air density, in kg/m , in this case ρ = 1 204 kg/m which corresponds to the air

ref ref
under standard condition (20°C, 101 325 Pa);
v is the mean air speed in the test duct, in m/s.
duct
with
4 ⋅ q
v,cor
v = (4)
duct
π ⋅ D
where
q is the corrected volume flow rate, in m /s;
v,cor
D is the test duct diameter, in m.
For each measurement, the pressure drop shall be calculated using Formula (5).
p p + p (5)
s,duct d,duct
where
Δp is the pressure drop, in Pa;
p is the static gauge pressure in the test duct, in Pa;
s,duct
p is the dynamic pressure in the test duct, in Pa.
d,duct

NOTE In this calculation method of the pressure drop, it is assumed that the thermal gravity effect (stack effect

in the test duct) is negligible.
5.2.3 Test method

The test shall be carried out by varying the flow rate through the air terminal device to give static pressure

differences of 5 Pa, 10 Pa, 20 Pa and 50 Pa with a tolerance of ± 1 Pa, between the test duct and the room

in which the test is carried out.
5.2.4 Analysis of results

It shall be checked whether the pressure drop can be expressed with a single pressure drop coefficient,

ζ, as given by Formula (6).
∆=pp ζ⋅ (6)
d,duct

To that effect, a linear regression line intercepting the point (p = 0; ΔP = 0) shall be searched through

d,duct

the obtained couples (p ; Δp) using an appropriate least squares method. For the regression line and

d,duct

Formula (6) to be valid in terms of this document, the coefficient of determination (r ) of the regression

line shall be ≥ 0,98. With a valid regression line, the pressure drop coefficient, ζ, equals the slope of the

line.
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
5.3 Suction effect of a cowl
5.3.1 General

In use, the cowl performance will combine both the suction effect due to the wind and the pressure drop

due to the air flowing through the cowl. The tests methods described in 5.3.3.2 and 5.3.3.3 measure the

performance of the cowl when these two effects are combined.

The test method described in 5.3.3.4 is used to characterize the effect of the fan for fan assisted cowls in

the absence of wind.

In use, when the auxiliary fan of an assisted cowl is switched on, the assisted cowl performance combines

both the suction effect due to the wind and due to the fan. The test described in 5.3.3.5 characterizes the

performance of the assisted cowl when these two effects are combined.

When testing a fan assisted cowl for tests without fan, the auxiliary fan shall be switched off and its blades

shall not be blocked.

The electric supply of the assisted cowl shall respond to the manufacturer specifications.

All tests shall be performed using the same cowl as in 5.2.
5.3.2 Measurements and calculations
The following parameters shall be measured:
— wind speed;
— air flow in test duct;
— static gauge pressure in test duct (Figure 2, Key 6);
— static gauge pressure in wind tunnel (Figure 2, Key 4);
— horizontal and vertical wind approach angles (see Figure 3 and Figure 4);
— atmospheric pressure;
— air temperature in the test duct.

The dynamic pressure of the wind, p , is calculated with the air speed measured at point 2 (see

d,tunnel
Figure 2) using Formula (7).
pv⋅ ρ ⋅ (7)
d,tunnel tunnel tunnel
where
p is the dynamic pressure in the wind tunnel, in Pa;
d,tunnel
is the air density in the wind tunnel, in kg/m ;
tunnel
v is the wind speed, in m/s.
tunnel

The difference between the total pressure in the test duct approaching the cowl and the static pressure

in the wind tunnel is calculated using Formula (8).
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SIST EN 13141-5:2021
EN 13141-5:2020 (E)
∆−pp= ∆p + p − p (8)
cowl d,duct f,duct s,,duct s tunnel
where

Δp is the difference between the total pressure in the test duct approaching the cowl under

cowl
test and the static pressure in the tunnel, in Pa;
Δp is the pressure drop due to friction
...

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