ISO 27327-2:2014

Fans — Air curtain units — Part 2: Laboratory methods of testing for sound power

ISO 27327-2:2014 deals with the determination of the acoustic performance of air curtain units. In addition, it can be used to determine the acoustic performance of air curtain units combined with an ancillary device.

Ventilateurs — Rideaux d'air — Partie 2: Méthodes d'essai en laboratoire des niveaux de puissance acoustique

General Information

• Status: Published
• Publication Date: 05-Feb-2014
• ICS: 17.140.20 - Noise emitted by machines and equipment
• ICS: 23.120 - Ventilators. Fans. Air-conditioners
• Technical Committee: ISO/TC 117 - Fans
• Drafting Committee: ISO/TC 117/WG 9 - Air curtain units
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 18-Sep-2019

Relations

• Revised: ISO 13347-2:2004 - Industrial fans — Determination of fan sound power levels under standardized laboratory conditions — Part 2: Reverberant room method
• Effective Date: 12-Jun-2010
• Revised: ISO 13347-1:2004 - Industrial fans — Determination of fan sound power levels under standardized laboratory conditions — Part 1: General overview
• Effective Date: 12-Jun-2010

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 27327-2
First edition
2014-02-15
Corrected version
2014-03-01
Fans — Air curtain units —
Part 2:
Laboratory methods of testing for
sound power
Ventilateurs — Rideaux d’air —
Partie 2: Méthodes d’essai en laboratoire des niveaux de puissance
acoustique
Reference number
ISO 27327-2:2014(E)
©
ISO 2014

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ISO 27327-2:2014(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved

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ISO 27327-2:2014(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and units . 2
3.1 Terms and definitions . 2
3.2 Air curtain unit sound power levels . 3
3.3 Other symbols . 3
4 Limitations on use . 4
4.1 General . 4
4.2 Noise source . 5
4.3 Character of noise . 5
4.4 Uncertainty . 5
4.5 Quantities to be measured . 5
5 Measurement uncertainty . 5
6 Instrumentation . 7
6.1 General . 7
6.2 Frequency analyser . 7
6.3 Turbulence screens and windshields . 7
6.4 Reference sound source (RSS) . 8
7 Test procedure . 8
7.1 Comparison method . 8
7.2 Direct method . 8
8 Acoustic environment . 8
8.1 Test environment . 8
8.2 Reverberant room . 8
9 Air curtain unit installation conditions . 9
10 Air curtain unit operating conditions . 9
10.1 General . 9
10.2 Measurement of ambient conditions . 9
10.3 Air curtain unit rotational speed . 9
10.4 Determination of air curtain unit aerodynamic operating point . 9
10.5 Control of air curtain unit operating condition . 9
11 Test setup . 9
11.1 Setup categories . 9
11.2 Sound pressure levels .14
11.3 Aerodynamic performance .15
11.4 Test conditions .15
11.5 Mounting methods .15
11.6 Microphone travel or positions .15
12 Information to be recorded .16
12.1 General .16
12.2 Air curtain unit under test .17
12.3 Acoustic environment .17
12.4 Acoustical data appropriate to the method of test.18
13 Calculations and evaluations .19
13.1 Calculation of one-third octave band levels .19
13.2 Calculation of overall sound power levels .19
13.3 Calculation of A-weighted sound power level .19
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ISO 27327-2:2014(E)

13.4 Background corrections .20
13.5 Sound power level, L .20
W
13.6 Evaluation .21
14 Test report .21
14.1 General .21
14.2 Description of test site, arrangement of fan, location of measuring points.21
14.3 Instrumentation used .22
14.4 Subjective assessment of the noise character .22
14.5 Measured values of the noise character .22
Annex A (normative) Effect of rotational speed changes .23
Annex B (normative) Uncertainty analysis .24
Annex C (normative) Calibration of reference sound source.28
Annex D (informative) Filter weighted measurements .30
Annex E (normative) Room qualification for sound sources with broadband sound .31
Annex F (informative) Room qualification for sound sources with pure tones/narrow-
band sound .33
Bibliography .37
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ISO 27327-2:2014(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 117, Fans.
ISO 27327 consists of the following parts, under the general title Fans — Air curtain units:
— Part 1: Laboratory methods of testing for aerodynamic performance rating
— Part 2: Laboratory methods of testing for sound power
The following parts are under preparation:
— Part 3: Test method to determine energy effectiveness [Technical Report]
This corrected version of ISO 27327-2:2014 incorporates the following correction:
— the sentence “This first edition of ISO 27327-2:2014 cancels and replaces ISO 13347-1:2004 and
ISO 13347-2:2004” has been removed from the Foreword.
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ISO 27327-2:2014(E)

Introduction
The need for this part of ISO 27327 has been evident for some time. While a number of national standards
exist for the measurement of fan noise, none addressed the particular considerations required for the
noise testing of air curtain units.
Forming part of the ISO/TC 117 series of fan standards, this part of ISO 27327 deals with the determination
of the air curtain unit sound power level appropriate to a particular application. In describing the test
and rating procedures, numerous references are made to ISO 5801 and ISO 13347, as well as to other ISO
standards.
The test procedures described in this part of ISO 27327 relate to laboratory conditions. The measurement
of performance under site conditions is not included. Acoustic system effects can be considerable where
the airflow into and out of the air curtain unit is not free from swirl nor fully developed.
This part of ISO 27327 describes methods for determining sound power levels of air curtain units in one-
third-octave bandwidths and one-octave bandwidths.
Data obtained in accordance with this part of ISO 27327 can be used for the following purposes, amongst
others:
a) comparison of air curtain units which are similar in size and type;
b) comparison of air curtain units which are different in size, type, design, speed, etc.;
c) determining whether an air curtain unit is suitable for a specified upper limit of sound emission;
d) scaling air curtain unit noise from one size and speed to another size and speed of the same type of
air curtain unit;
e) prediction of sound pressure level in application of the air curtain unit;
f) engineering work to assist in developing machinery and equipment with lower sound emissions.
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INTERNATIONAL STANDARD ISO 27327-2:2014(E)
Fans — Air curtain units —
Part 2:
Laboratory methods of testing for sound power
1 Scope
This part of ISO 27327 deals with the determination of the acoustic performance of air curtain units.
In addition, it can be used to determine the acoustic performance of air curtain units combined with an
ancillary device.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 266:1997, Acoustics — Preferred frequencies
ISO 3740:2000, Acoustics — Determination of sound power levels of noise sources — Guidelines for the use
of basic standards
ISO 3741:2010, Acoustics — Determination of sound power levels and sound energy levels of noise sources
using sound pressure — Precision methods for reverberation test rooms
ISO 3743-1, Acoustics — Determination of sound power levels and sound energy levels of noise sources
using sound pressure — Engineering methods for small movable sources in reverberant fields — Part 1:
Comparison method for a hard-walled test room
ISO 3743-2, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Engineering methods for small, movable sources in reverberant fields — Part 2: Methods for special
reverberation test rooms
ISO 3747, Acoustics — Determination of sound power levels and sound energy levels of noise sources using
sound pressure — Engineering/survey methods for use in situ in a reverberant environment
ISO 5801:2007, Industrial fans — Performance testing using standardized airways
ISO 6926:1999, Acoustics — Requirements for the performance and calibration of reference sound sources
used for the determination of sound power levels
ISO 13347-1:2004, Industrial fans — Determination of fan sound power levels under standardized laboratory
conditions — Part 1: General overview
ISO 13347-2:2004, Industrial fans — Determination of fan sound power levels under standardized laboratory
conditions — Part 2: Reverberant room method
ISO 13349:2010, Fans — Vocabulary and definitions of categories
ISO 27327-1:2009, Fans — Air curtain units — Part 1: Laboratory methods of testing for aerodynamic
performance rating
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ISO 27327-2:2014(E)

3 Terms, definitions, symbols and units
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3740, ISO 3747, ISO 5801,
ISO 13347-1, ISO 13347-2, ISO 13349, ISO 27327-1 and the following apply.
3.1.1
inlet sound power level
sound power level of an air curtain unit determined at the air curtain unit inlet in test installation type A
3.1.2
outlet sound power level
sound power level of an air curtain unit determined at the air curtain outlet in test installation type A
3.1.3
total sound power level
sound power level of an air curtain unit in test installation type E
3.1.4
casing sound power level
sound power level radiated from an air curtain unit casing
Note 1 to entry: If the air curtain unit drive is external to the air curtain unit casing, the casing sound power shall
include the sound power generated by and radiated from the air curtain unit drive.
3.1.5
frequency range of interest
frequency range including octave bands with centre frequencies between 63 Hz and 8 000 Hz and one-
third octave bands with centre frequencies between 50 Hz and 10 000 Hz
Note 1 to entry: For special purposes, the frequency range can be extended at either end, provided that the test
environment and instrument accuracy are satisfactory for use over the extended frequency range. For air curtain
units which radiate sound at predominantly high (or low) frequency, the frequency range of interest can be limited
in order to optimize the test facility and procedures.
3.1.6
blade passage frequency (BPF)
frequency of air curtain unit impeller blades passing a single fixed object
Note 1 to entry: The blade passage frequency is calculated by the following formula:
xn
BPF= Hz
60
where
x is the number of blades;
n is the fan speed, expressed in revolutions per minute.
3.1.7
chamber
enclosure used to regulate flow and absorb sound; it can also conform to air test chamber conditions
outlined in ISO 5801
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ISO 27327-2:2014(E)

3.1.8
air curtain unit inlet area
Α
1
summation of open areas (slots, holes, louvres, openings, etc.) through which air will flow into the air
curtain unit; normally a grille and/or air inlet opening
3.1.9
air curtain unit outlet area
Α
2
summation of open areas through which air will discharge out of the air curtain; normally a grille and/or
air outlet opening
3.1.10
reverberant room
enclosure meeting the requirements of Annex A and/or Annex B of ISO 13347-2:2004
3.1.11
standard air
3
air with a density of 1,2 kg/m
-3
Note 1 to entry: Standard air has a ratio of specific heats of 1,4 and a viscosity of 1,815 × 10 kg/m·s.
Note 2 to entry: Air at 16 °C dry bulb temperature, 50 % relative humidity, and 100 kPa barometric pressure has
these properties, but this is not part of the definition.
Note 3 to entry: Air at 20 °C dry bulb temperature, 50 % relative humidity, and 101,325 kPa barometric pressure
has these properties, but this is not part of the definition.
3.2 Air curtain unit sound power levels
Considering all possible combinations for installation conditions specified in Clause 4, five different
sound power level (L ) descriptions are defined in Table 1, e.g. L (A,in).
W W
Table 1 — Sound power levels
Number Suffix Description
1 (A,in) free-inlet sound power level, type A installation
2 (A,out) free-outlet sound power level; type A installation
total sound power level; type E installation (includes the contributions from the
3 (E,tot)
inlet, outlet, casing, and drive)
4 (A,in+cas) free-inlet sound power level plus casing-radiated noise; type A installation
5 (A,out+cas) free-outlet sound power level plus casing-radiated noise; type A installation
NOTE 1 All of these symbols can be used to indicate levels in one-third octave or octave frequency bands, as well as overall
sound power levels and A-weighted sound power levels, provided that the sound power to which the symbols relate is clearly
defined.
Where noise from the drive can contribute to the noise radiated from a casing, then this should be clearly stated by the
addition of “+dr”, e.g. L (A,in+cas+dr).
W
NOTE 2 Not all of the above levels need to be measured for a particular air curtain unit.
NOTE 3 Where some portion of inlet noise is included in the measurement of outlet noise, this shall be clearly stated by the
addition of “+in” or other similar notation, e.g. L (A,out+in).
W
3.3 Other symbols
For consistency and mutual understanding, it is recommended that the symbols and units shown in
Table 2 be used in reporting and calculation. Unless otherwise noted, the subscript number refers to the
mid-frequency of the octave band or one-third octave band number.
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ISO 27327-2:2014(E)

Table 2 — Symbols, units
Symbol Term SI unit
2
A air curtain unit inlet area m
1
2
A air curtain unit outlet area m
2
   c speed of sound m/s
minimum distance between equipment under test and reverberant room measure-
D m
min
ment surface
f frequency Hz
−5
L sound pressure level, re 20 μPa (2 × 10 Pa) dB
p
L corrected sound pressure level of the air curtain unit dB
pc
recorded sound pressure level of room background as measured over the normal
L dB
pb
microphone path
L
background sound pressure level dB
pb

recorded sound pressure level of air curtain unit and room background as meas-
L dB
pm
ured over the normal microphone path
L corrected sound pressure level of the RSS dB
pq
recorded sound pressure level of the RSS and room background as measured over
L dB
pqm
the normal microphone path
L recorded sound pressure level of pure tone noise source dB
ps
−12
L sound power level, re 1 pW (1 × 10 W) dB
W
L sound power level of RSS dB
Wr
λ wavelength m
M Mach number dimensionless
p sound pressure Pa
−5
p reference sound pressure, 20 μPa (2 × 10 Pa) -
ref
s standard deviation dB
θ air temperature K
W sound power W
−12
W reference sound power, re 1 pW (1 × 10 W) dB
ref
4 Limitations on use
4.1 General
For reverberant room tests, the size of the air curtain unit is limited to less than 2 % of the room volume.
The test procedures specified in this part of ISO 27327 are intended principally for tests conducted
using standardized test configurations and under specified environments and conditions and cannot be
appropriate to site test conditions.
The air curtain unit installation conditions conform to the following two categories of installation types:
— type A: free inlet, free outlet;
Used when measuring inlet noise only or outlet noise only, i.e. (i) ducted ACUs or (ii) recessed ACUs
where the air inlet and air discharge of the ACU communicate with separate spaces (air inlet – ceiling
void; air discharge – space to be served)
— type E: free inlet, free outlet.
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ISO 27327-2:2014(E)

Used when measuring total noise; i.e. (i) surface-mounted ACUs or (ii) recessed ACUs where the air
inlet and air discharge of the ACU communicate with the same space
4.2 Noise source
The noise source is an air curtain unit. The noise measured can contain contributions from the fan drive
and transmission.
4.3 Character of noise
Steady broadband with discrete frequency tones.
4.4 Uncertainty
Engineering grade, as defined in ISO 3740.
4.5 Quantities to be measured
Sound pressure levels in one-third octave frequency bands at discrete microphone positions or on a
prescribed path.
Air curtain unit aerodynamic performance indicators, where applicable, e.g. rotational speed, static
pressure, and flow rate.
5 Measurement uncertainty
Measurements made in conformance with this part of ISO 27327 tend to result in standard deviations
which are equal to or less than those given in Table 3. These standard deviations take into account
the cumulative effects of all causes of measurement uncertainty such as source location, instrument
calibration, and sampling. They do not reflect variations in the sound power radiated by the air curtain
unit itself due to, for example, changes in installation type or manufacturing tolerances. For further
information, refer to Annex B.
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ISO 27327-2:2014(E)

Table 3 — Uncertainty in determination of the frequency-band sound power levels
One-third octave band Standard deviation
frequencies

Hz dB
50
63 6,0*
80
100
125 3,0
160
200
250 3,0
315
400
500 3,0
630
800
1000 3,0
1250
1600
2000 3,0
2500
3150
4000 3,0
5000
6300
8000 3,0
10000
The uncertainties in Table 3 do not allow for the variations in sound power levels due to manufacturing
tolerances. These are consequent differences between one air curtain unit and another of the same
nominal design, rotational speed, etc. In any specifications which are part of a contract, it is necessary to
apply tolerances to sound values. These can be calculated for a n
...

DRAFT INTERNATIONAL STANDARD ISO/DIS 27327-2
ISO/TC 117 Secretariat: BSI
Voting begins on Voting terminates on

2012-10-01 2013-01-01
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION    МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ    ORGANISATION INTERNATIONALE DE NORMALISATION


Fans — Air curtain units —
Part 2:
Laboratory methods of testing for sound power
Ventilateurs — Rideaux d'air —
Partie 2: Méthodes d'essai en laboratoire des niveaux de puissance acoustique
[Revision of first edition (ISO 13347-1:2004, ISO 13347-1:2004/Cor.1:2006, ISO 13347-2:2004 and
ISO 13347-2:2004/Cor.1:2006)]
ICS 17.140.20; 23.120









To expedite distribution, this document is circulated as received from the committee
secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at
publication stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.



THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME
STANDARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
©  International Organization for Standardization, 2012

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ISO/DIS 27327-2

Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
photocopying, recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s
member body in the country of the requester.
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Fax + 41 22 749 09 47
E-mail [e-mail]
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Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.

ii © ISO 2012 – All rights reserved

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ISO/CD 27327-2
Contents Page
1  Scope . 1
2  Normative References . 1
3  Terms, definitions, symbols and units . 2
3.1  Terms and definitions . 2
3.2  Air curtain unit sound power levels . 3
3.3  Other Symbols . 4
4  Limitations on use . 5
4.1  General . 5
4.2  Noise source . 5
4.3  Character of noise . 5
4.4  Uncertainty . 5
4.5  Quantities to be measured . 5
5  Measurement uncertainty . 5
6  Instrumentation . 7
6.1  General . 7
6.1.1  Microphone . 7
6.1.2  Microphone cable . 7
6.1.3  Sound level meter or other microphone amplifier . 7
6.2  Frequency analyser . 7
6.3  Turbulence screens and windshields . 8
6.3.1  Windshields . 8
6.3.2  Wind-generated false noise . 8
6.4  Reference sound source (RSS) . 8
7  Test procedure . 8
7.1  Comparison method . 8
7.2  Direct method . 8
8  Acoustic environment . 8
8.1  Test environment . 8
8.2  Reverberant room . 9
9  Air curtain unit installation conditions . 9
10  Air curtain unit operating conditions . 9
10.1  General . 9
10.2  Measurement of ambient conditions . 9
10.3  Air curtain unit rotational speed . 9
10.4  Determination of air curtain unit aerodynamic operating point . 9
10.5  Control of air curtain unit operating condition . 9
11  Test set-up . 10
11.1  Set-up categories . 10
11.2  Sound pressure levels . 15
11.2.1  Sound pressure levels, background (L ) . 15
pb
11.2.2  Sound pressure levels, RSS (L ) . 15
pqm
11.2.3  Sound pressure levels, air curtain unit (L ). 15
p
11.3  Aerodynamic performance . 15
11.4  Test conditions . 15
11.5  Mounting methods . 16
11.6  Microphone travel or positions . 17
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ISO/CD 27327-2
12  Information to be recorded .19
12.1  General .19
12.2  Air curtain unit under test .19
12.2.1  Description of the air curtain unit under test .19
12.2.2  Operating conditions .19
12.2.3  Mounting conditions .19
12.3  Acoustic environment .19
12.3.1  Description of the test environment and method .19
12.3.2  Acoustical qualification of the test environment .20
12.3.3  Test data .20
12.3.4  Laboratory and instrumentation .20
12.3.5  Location of the air curtain unit in the test environment .20
12.3.6  Additional noise sources .20
12.4  Acoustical data appropriate to the method of test .20
13  Calculations and evaluations .21
13.1  Calculation of one-third octave band levels .21
13.2  Calculation of overall sound power levels .21
13.3  Calculation of A-weighted sound power level .22
13.4  Background corrections .22
13.5  Sound power level, L .23
W
13.6  Evaluation .23
14  Test report .23
14.1  General .23
14.2  Description of test site, arrangement of fan, location of measuring points .24
14.3  Instrumentation used .24
14.4  Subjective assessment of the noise character .24
14.5  Measured values of the noise character .24
Annex A (normative) Effect of rotational speed changes .25
Annex B (normative) Uncertainty analysis.26
B.1  General .26
B.2  Definitions .26
B.3  Uncertainties .26
B.4  Room response .26
B.4.1  Broad-band measurement in a reverberant room .27
B.4.2  Pure tone measurement in a reverberant room .27
B.4.3  Test for discrete-frequency components .27
B.5  Air curtain unit operating points .28
B.6  Instrument error .28
B.7  Reference sound source (RSS) .29
B.8  Octave band VS one-third octave band .29
Annex C (normative) Calibration of reference sound source .30
C.1  General .30
C.2  Equipment and facilities .30
C.3  Qualification .30
C.4  Procedure .30
C.5  RSS sound power levels .31
Annex D (informative) Filter weighted measurements .32
Annex E (normative) Room qualification for sound sources with broad-band sound .33
E.1  General .33
E.2  Instrumentation and equipment .33
E.3  Test procedures .33
E.4  Computation procedures .33
E.5  Qualification .34
Annex F (informative) Room qualification for sound sources with pure tones/narrow-band sound .35
F.1  General .35
F.2  Instrumentation and equipment .35
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ISO/CD 27327-2
F.3  Test procedure . 35
F.3.1  Loudspeaker test . 35
F.3.2  Room test . 36
F.4  Computation . 36
F.5  Qualification . 36

© ISO 2011 – All rights reserved v

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ISO/CD 27327-2
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 27327-2 was prepared by Technical Committee ISO/TC 117, Fans, Subcommittee SC , .
ISO 27327 consists of the following parts, under the general title Fans — Air Curtain Units:
Part 1: Laboratory methods of testing for aerodynamic performance rating
Part 2: Determination of air curtain unit sound power levels under standardized laboratory conditions -
reverberant room method
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ISO/CD 27327-2
Introduction
The need for this new International Standard, ISO 27327-2, has been evident for some time. Whilst a number
of national standards exist for the measurement of fan noise, none addressed the particular considerations
required for the noise testing of air curtain units.
Forming part of the ISO/TC 117 series of fan standards, this part of ISO 27327 deals with the determination of
the air curtain unit sound power level appropriate to a particular application. In describing the test and rating
procedures, numerous references are made to ISO 5801 and ISO 13347 as well as to other ISO standards.
The test procedures described in this part of ISO 27327 relate to laboratory conditions. The measurement of
performance under site conditions is not included. Acoustic system effects can be considerable where the
airflow into and out of the air curtain unit is not free from swirl, nor fully developed.
This part of ISO 27327 describes methods for determining sound power levels of air curtain units in one-third-
octave bandwidths and one-octave bandwidths.
Data obtained in accordance with this part of ISO 27327 may be used for the following purposes amongst
others:
a) comparison of air curtain units which are similar in size and type;
b) comparison of air curtain units which are different in size, type, design, speed, etc.;
c) determining whether an air curtain unit is suitable for a specified upper limit of sound emission;
d) scaling air curtain unit noise from one size and speed to another size and speed of the same type of air
curtain unit
e) prediction of sound pressure level in application of the air curtain unit;
f) engineering work to assist in developing machinery and equipment with lower sound emissions.
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COMMITTEE DRAFT ISO/CD 27327-2

Fans — Air Curtain Units - Determination of air curtain unit
sound power levels under standardized laboratory conditions -
reverberant room method
1 Scope
This part of ISO 27327 deals with the determination of the acoustic performance of air curtain units. In addition,
it may be used to determine the acoustic performance of air curtain units combined with an ancillary device.
2 Normative References
The following referenced documents are indispensible for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 266:1997, Acoustics – Preferred frequencies
ISO 3740:2000, Acoustics – Determination of sound power levels of noise sources – Guidelines for the use of
basic standards
ISO 3741:2010, Acoustics – Determination of sound power levels and sound energy levels of noise sources
using sound pressure – Precision methods for reverberation test rooms
ISO 3743-1:2010, Acoustics – Determination of sound power levels and sound energy levels of noise sources
using sound pressure – Engineering methods for small movable sources in reverberant fields – Part 1:
Comparison method for hard-walled test room
ISO 3743-2:1994, Acoustics – Determination of sound power levels of noise sources using sound pressure –
Engineering methods for small, movable sources in reverberant fields – Part 2: Methods for special
reverberation test rooms
ISO 5801:2007, Industrial fans – Performance testing using standardized airways
ISO 6926:1999, Acoustics – Requirements for the performance and calibration of reference sound sources
used for the determination of sound power levels
ISO 10302-1:2011, Acoustics –Measurement of airborne noise emitted and structure-borne vibration induced
by small air-moving devices – Part 1: Airborne noise measurement
ISO 13347-1:2004, Industrial Fans – Determination of fan sound power levels under standardized laboratory
conditions – Part 1: General overview
ISO 13347-2:2004, Industrial Fans – Determination of fan sound power levels under standardized laboratory
conditions – Part 2: Reverberant room method
ISO 13349:2010, Fans – Vocabulary and definitions of categories
ISO 27327-1:2009, Fans – Air curtain units – Part 1: Laboratory methods of testing for aerodynamic
performance rating
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ISO/CD 27327-2
ISO 80000-1:2009, Quantities and units – Part 1: General
3 Terms, definitions, symbols and units
3.1 Terms and definitions
For the purposes of this document, the non-acoustical terms and units defined in ISO 5801, ISO 13349, ISO
27327-1, and ISO 1000 apply. The following definitions also apply, and are taken from ISO 3740 to 3747, ISO
13347-1, and ISO 13347-2 wherever possible. Some definitions have been expanded to fit the specific needs
of this document.
3.1.1
inlet sound power level
sound power level of an air curtain unit determined at the air curtain unit inlet in test installation type A.
3.1.2
outlet sound power level
sound power level of an air curtain unit determined at the air curtain outlet in test installation type A.
3.1.3
total sound power level
sound power level of an air curtain unit in test installation type E.
3.1.4
casing sound power level
sound power level radiated from an air curtain unit casing.
NOTE If the air curtain unit drive is external to the air curtain unit casing, the casing sound power shall include the
sound power generated by and radiated from the air curtain unit drive
3.1.5
frequency range of interest
frequency range including octave bands with centre frequencies between 63 Hz and 8 000 Hz and one-third
octave bands with centre frequencies between 50 Hz and 10 000 Hz.
NOTE For special purposes, the frequency range may be extended at either end, provided that the test environment
and instrument accuracy are satisfactory for use over the extended frequency range. For air curtain units which radiate
sound at predominantly high (or low) frequency, the frequency range of interest may be limited in order to optimise the test
facility and procedures.
3.1.6
blade passage frequency (BPF)
frequency of air curtain unit impeller blades passing a single fixed object.
NOTE The blade passage frequency is calculated by the following formula:
xn×
BPF = Hz
60
where
x is the number of blades;
n is the fan speed, expressed in revolutions per minute.
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ISO/CD 27327-2
3.1.7
chamber
enclosure used to regulate flow and absorb sound; it may also conform to air test chamber conditions outlined
in ISO 5801.
3.1.8
air curtain unit inlet area
Α
1
summation of open areas (slots, holes, louvres, openings, etc.) through which air will flow into the air curtain unit; normally
a grille and/or air inlet opening
3.1.9
air curtain unit outlet area
Α
2
summation of open areas through which air will discharge out of the air curtain; normally a grille and/or air
outlet opening.
3.1.10
reverberant room
enclosure meeting the requirements of Annex A and/or Annex B of ISO 13347-2:2004
3.1.11
standard air
3
air with a density of 1,2 kg/m
NOTE 1 Standard air has a ratio of specific heats of 1,4 and a viscosity of 1,815 E-03 kg/m • s
NOTE 2 Air at 16 °C dry bulb temperature, 50 % relative humidity, and 100 kPa barometric pressure has these
properties, but this is not part of the definition.
NOTE 3 Air at 20 °C dry bulb temperature, 50 % relative humidity, and 101.325 kPa barometric pressure has these
properties, but this is not part of the definition.
3.2 Air curtain unit sound power levels
Considering all possible combinations for installation conditions specified in Clause 4, five different sound
power level (L ) descriptions are defined in Table 1; e.g., L (A,in).
W W
Table 1 — Sound power levels
Number Suffix Description
1 (A,in) free-inlet sound power level, type A installation.
2 (A,out) free-outlet sound power level; type A installation.
total sound power level; type E installation (includes the contributions from the
3 (E,tot)
inlet, outlet, casing, and drive).
4 (A,in+cas) free-inlet sound power level plus casing-radiated noise; type A installation
5 (A,out+cas) free-outlet sound power level plus casing-radiated noise; type A installation

NOTE 1 All of these symbols may be used to indicate levels in one-third octave or octave frequency bands as well as
overall sound power levels and A-weighted sound power levels, provided that the sound power to which the symbols
relate is clearly defined.
Where noise from the drive may contribute to the noise radiated from a casing, then this should be clearly stated by the
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ISO/CD 27327-2
addition of +dr e.g., L (E,cas + dr).
W
NOTE 2 Not all of the above levels need to be measured for a particular air curtain unit.
NOTE 3 Where some portion of inlet noise is inclu
...