ISO 10302-1:2024

International
Standard
ISO 10302-1
Second edition
Acoustics — Measurement of
2024-02
airborne noise emitted and
structure-borne vibration induced
by small air-moving devices —
Part 1:
Airborne noise measurement
Acoustique — Mesurage du bruit aérien émis et des vibrations de
structure induites par les petits équipements de ventilation —
Partie 1: Mesurage du bruit aérien
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 General definitions.2
3.2 Acoustical definitions .2
3.3 Aerodynamic definitions .3
4 Limitations of measurement . 4
5 Design and performance requirements for test plenum . 5
5.1 General .5
5.2 Test plenum: main assembly .6
5.3 Mounting panel assembly .6
5.4 Adjustable exit port assembly . .7
5.5 Insertion loss of test plenum .7
5.6 Instrumentation for static pressure measurement .7
6 Installation . 8
6.1 Installation of test plenum in test room .8
6.2 Direction of airflow .8
6.3 Mounting of air-moving device .8
7 Operation of air-moving device . 8
7.1 Input power .8
7.1.1 Alternating current (AC) air-moving devices .8
7.1.2 Direct current (DC) air-moving devices .8
7.2 Points of operation (AC and DC air-moving devices) .9
7.2.1 Required points of operation .9
7.2.2 Method A (conventional method) .9
7.2.3 Method B (alternative method) .9
7.2.4 Procedure .10
8 Measurement procedures .10
8.1 General .10
8.2 Microphone positions for measurements in an essentially free field over a reflecting
plane . . .11
8.2.1 General .11
8.2.2 Fixed points on a hemisphere .11
8.2.3 Coaxial circular paths in five or more parallel planes .11
8.3 Preparations for measurements .11
8.4 Operational test of air-moving device . 12
9 Measurement uncertainty .12
10 Information to be recorded .13
11 Information to be reported .13
Annex A (normative) Micro-fan p-q curve measurement method .24
Annex B (informative) Effects of air density .26
Annex C (informative) Data formats for presentation .27
Annex D (informative) Air-moving device acoustical noise specification .32
Annex E (informative) Guidance on the development of information on measurement
uncertainty .33

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This second edition cancels and replaces the first edition (ISO 10302-1:2011), which has been technically
revised.
The main changes are as follows:
— In Clause 3, the most terms were editorially improved with no technical changes, and their cross-
references to the main body were also clarified.
— In Clause 4, the allowable fan static pressure range, 750 Pa for a full-size plenum, was extended up to
1,500 Pa for a half-size plenum and 3,000 Pa for a quarter-size plenum.
— In Clause 7, for the selection of points of operation, in addition to the existing Method A (conventional
method), Method B (alternative method) was introduced.
— In Clause 11, Note was amended to clarify the reference to Annex D.
— In Annex A, to be consistent to the definition of micro-fan (3.1.2), the abscissa of Figure A.1 and related
descriptions were amended.
A list of all parts in the ISO 10302 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
This document shows in detail methods for determining and reporting the airborne noise emissions of small
air-moving devices (AMDs) used primarily for cooling electronic equipment, such as that for information
technology and telecommunications.
To provide compatibility with measurements of acoustical noise emitted by such equipment, this document
uses the noise emission descriptors and sound power measurement methods of ISO 7779. The descriptor of
overall airborne noise emission of the AMD under test is the A-weighted sound power level. The one-third-
octave-band sound power level is the detailed descriptor of the noise emission. Octave-band sound power
levels may be provided in addition to the one-third-octave-band sound power levels.

v
International Standard ISO 10302-1:2024(en)
Acoustics — Measurement of airborne noise emitted and
structure-borne vibration induced by small air-moving
devices —
Part 1:
Airborne noise measurement
1 Scope
This document specifies methods for measuring the airborne noise emitted by small air-moving devices
(AMDs), such as those used for cooling electronic, electrical, and mechanical equipment where the sound
power level of the AMD is of interest.
Examples of these AMDs include propeller fans, tube-axial fans, vane-axial fans, centrifugal fans, motorized
impellers, and their variations.
This document describes the test apparatus and methods for determining the airborne noise emitted by
small AMDs as a function of the volume flow rate and the fan static pressure developed by the AMD on the
test apparatus. It is intended for use by AMD manufacturers, by manufacturers who use AMDs for cooling
electronic equipment and similar applications, and by testing laboratories. It provides a method for AMD
manufacturers, equipment manufacturers and testing laboratories to obtain comparable results. Results of
measurements made in accordance with this document are expected to be used for engineering information
and performance verification, and the methods can be cited in purchase specifications and contracts
between buyers and sellers. The ultimate purpose of the measurements is to provide data to assist the
designers of electronic, electrical or mechanical equipment which contains one or more AMDs.
Based on experimental data, a method is given for calculating the maximum volume flow rate of the scaled
plenum up to which this document is applicable.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3741, Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound
pressure — Precision methods for reverberation test rooms
ISO 3744, Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound
pressure — Engineering methods for an essentially free field over a reflecting plane
ISO 3745, Acoustics — Determination of sound power levels and sound energy levels of noise sources using sound
pressure — Precision methods for anechoic rooms and hemi-anechoic rooms
ISO 5801, Fans — Performance testing using standardized airways
ISO 7779:2018, Acoustics — Measurement of airborne noise emitted by information technology and
telecommunications equipment
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
me a s ur ement (GUM: 1995)
ANSI/ASA S2.32, Methods for the experimental determination of mechanical mobility — Part 2: Measurements
using single-point translational excitation
JBMS -72 -1: 2010, Acoustics — Method for the measurement of airborne noise emitted and structure-borne
vibration induced by small air-moving devices — Part 1: Airborne noise measurement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7779 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General definitions
3.1.1
air-moving device
AMD
fan
device for moving air which utilizes a rotating impeller driven by an electric motor with electronic or
mechanical command
Note 1 to entry: An air-moving device has at least one inlet opening and at least one outlet opening. The openings can
have elements for connection to ductwork or to other parts of the airflow path.
Note 2 to entry: Tests can be run with a particular frame, motor, and rotor, but with different accessories (e.g. finger
guards). For the purposes of this document, each such configuration is referred to as an air-moving device.
Note 3 to entry: Within some industries, including information technology, the unmodified term “fan” means “axial
flow air-moving device”, and the unmodified term “blower” means “centrifugal air-moving device”. In this document,
the term “fan” is used to mean “air-moving device” and does not necessarily imply axial flow. Modifiers (such as axial,
centrifugal or mixed flow) are added as necessary to distinguish between types.
3.1.2
micro-fan
air-moving device (3.1.1) which has a maximum volume flow rate less than or equal to 0,015 m /s
Note 1 to entry: Micro-fans are a subset of fans under test according to this document.
Note 2 to entry: ISO 5801 limits the range of applicability to Reynolds numbers of 12 000 or higher. This Reynolds
number corresponds to the lower limit of volume flow rate of approximately 0,01 m /s. Since lower volume fans are of
1)
interest for many cooling applications, the methodology of JBMS -72 -1: 2010, Annex A is used to measure the p-q curve
of a micro-fan.
3.2 Acoustical definitions
3.2.1
sound power level
L
W
ten times the logarithm to the base 10 of the ratio of the sound power, P, to a reference value, P , expressed
in decibels
P
L =10lg
W
P
1) The English version of JBMS -72-1: 2010, Annex A is freely available from https:// hyojunka .jbmia .or .jp/ hyojun2/
upload -v3/ archive/ JBMS -72 -1 -1 .pdf.

where the reference value, P , is 1 pW
[8]
Note 1 to entry: If a specific frequency weighting as specified in IEC 61672-1 and/or specific frequency bands are
applied, this should be indicated by appropriate subscripts; e.g. L denotes the A-weighted sound power level.
WA
3.2.2
frequency range of interest
range extending from the 100 Hz one-third-octave band to the 10 kHz one-third-octave band
[1]
Note 1 to entry: The centre frequencies of these one-third-octave bands are defined in ISO 266 .
Note 2 to entry: For small, low-noise fans to be measured (i.e., micro-fans), depending on the size of applicable plenum,
the radius of the test hemisphere may be reduced to less than 1 m, but not less than 0,5 m (see 8.2.1). However, a radius
less than 1 m could itself impose limits on the frequency range over which tests are performed. For details, reference
is made to ISO 7779:2018, B.1.
3.2.3
insertion loss of test plenum
ΔL
sound power level (3.2.1) difference due to the presence of test plenum, defined as follows:
ΔLL=−L
WWW ,,outin
where
L
is the sound power level, in decibels, of a sound source determined when installed outside the
W ,out
test plenum;
L
is the sound power level, in decibels, of a sound source determined when installed inside the
W ,in
test plenum.
Note 1 to entry: The insertion loss of the test plenum is expressed in decibels.
3.3 Aerodynamic definitions
3.3.1
test plenum
structure on to which the air-moving device under test is mounted for acoustical noise emission
measurements
Note 1 to entry: The plenum provides a flow resistance to the air-moving device, but permits sound from the air-
moving device to radiate freely into the test room with only minimal attenuation. Thus, the sound power radiated by
the air-moving device can be determined from acoustical measurements made outside the test plenum.
3.3.2
AMD aerodynamic performance curve
p-q curve
presentation of fan static pressure as a function of volume flow rate under standard air conditions (3.3.6) and
constant operating voltage and frequency
Note 1 to entry: For the purpose of this document, a qualifier, “aerodynamic”, before “performance curve” is inserted
to distinguish from acoustical noise emission characteristics against volume flow rate.
Note 2 to entry: The presentation is derived in accordance with ISO 5801 or Annex A, which complement each other.
The method for small air-moving devices of volume flow rate up to 0,015 m /s is specified in Annex A.
Note 3 to entry: For convenience, in this document, the term “p-q curve” is used.

3.3.3
point of operation
point on the AMD aerodynamic performance curve (3.3.2) corresponding to a particular volume flow rate
Note 1 to entry: The point of operation is controlled during a test by adjusting the “slider” on the test plenum exit port
assembly.
3.3.4
overall static efficiency
η
o,s
volume flow rate multiplied by the fan static pressure and divided by the
input electrical power
Note 1 to entry: The overall static efficiency, η , expressed as a percentage, is given by
o,s
pq
s,f V
η =× 100
o,s
P
input
where
p
is the fan static pressure, in pascals;
s,f
q
is the volume flow rate, in cubic metres per second;
V
P
is the motor input power, in watts (true power, not including reactive component), supplied at
input
the terminals of the electric drive motor.
Note 2 to entry: The air-moving device is defined to include the motor, impeller and frame; therefore, the overall static
efficiency includes both the electromechanical efficiency of the motor and the aerodynamic efficiency of the impeller
and frame.
3.3.5
standard air density
density under standard air conditions (3.3.6)
Note 1 to entry: The value is 1,20 kg/m .
3.3.6
standard air conditions
specified meteorological conditions
Note 1 to entry: For the purposes of this document, the conditions are: 20 °C temperature; 50 % relative humidity; and
1,013 × 10 Pa ambient pressure.
4 Limitations of measurement
This method is useful up to the maximum volume flow rate, q , as a function of nominal air volume, V, of
V,max
the plenum used and up to a fan static pressure of 750 Pa.
Based on experimental data and modelled results, the allowable fan static pressure range is extended up to
at least 750 Pa for a full-size plenum, 1 500 Pa for a half-size plenum and 3 000 Pa for a quarter-size plenum.
NOTE 1 For static pressures above 750 Pa, the integrity of the plenum and the measurement can be impacted by
the thickness of the polyester film, the size of the plenum, and the construction of the mounting plate and the outlet
port. A thinner polyester film and a larger plenum size will result in increased strain on the polyester film. If a fan is
operating at a static pressure above 750 Pa, closely monitor for leaks, particularly around the mounting panel and
outlet port. See References [14] and [15] for details.
q
V,0
q = V (1)
V,max
V
where
q
is the maximum volume flow rate of the scaled plenum, in cubic metres per second;
V,max
q
V ,0 is the maximum volume flow rate of the full-size plenum, in cubic metres per second, q = 1ms/;
V ,0
V
is the nominal air volume of the full-size plenum defined in Clause 6, in cubic metres, V =13,; m
V
is the nominal air volume of the scaled plenum, in cubic metres.
NOTE 2 The value of the interior air volume of a full-size plenum of 1,3 m is rounded up from
1,296 m = 1,2 m (width) × 1,2 m (depth) × 0,9 m (height).
NOTE 3 It is noted that the “nominal air volume” means approximate air volume calculated from the outer
dimensions of the plenum. For instance, in case of 1/4 sized plenum, the nominal air volume of the plenum, excluding
the leg height, becomes V = b · l · h = 0,3 m × 0,3 m × 0,225 m = 0,020 25 m , where b is width, l is depth, and h is height.
For the purposes of this document, it is recommended that the smallest plenum possible be applied, provided
that the maximum volume flow rate of the fan is within the limit of Formula (1).
The method defined in this document, by reference to ISO 7779, provided for determination of sound power
levels in a qualified environment, shall use either a comparison method in a reverberation test room based
on ISO 3741, or a direct method in essentially free-field conditions over a reflecting plane based on ISO 3744
or ISO 3745. The method specified in this document can be applied to air-moving devices (AMDs) which
radiate: a) broad-band noise; b) narrow-band noise; or c) noise that contains discrete frequency components.
The method specified in this document permits the determination of acoustical noise emission levels for an
individual unit under test. If these levels are determined for several units of the same production series, the
results may be used to determine a statistical value for the production series.
CAUTION — Vibration, flow disturbances, insertion loss and other phenomena can alter radiated
sound power in the actual application; therefore, the results of measurements made in accordance
with this document can differ from the results obtained when AMDs are installed in equipment.
NOTE 4 This document does not describe measurement of the structure-borne noise generated by AMDs.
5 Design and performance requirements for test plenum
5.1 General
The design specified is intended to meet the limits stated for maximum volume flow rate and maximum fan
static pressure. The design provides an acoustically transparent, adjustable flow resistance to the AMD.
NOTE 1 See 5.5 for requirements for confirming acoustical transparency in accordance with this document.
The reference design of the plenum is specified in 5.2 to 5.6 and shown in Figure 1 to Figure 8. Also
addressed in these subclauses and elsewhere in this document are permitted variations from this design,
primarily the option of reducing the linear dimensions of the frame and some dimensions of other parts,
while maintaining geometric proportions, in the range from full to quarter scale. Such a reduction reduces
the maximum permitted volume flow rate of AMDs to be tested in direct proportion to the reduction in
volume of the plenum [see Formula (1)], i.e. by the linear scale raised to the third power.
NOTE 2 These variations can better accommodate the use of smaller or quieter fans as well as test chambers with
doors too narrow for the reference design plenum.
Permitted variations have been shown to yield standard deviations of reproducibility within the range
of Table 1. The degree to which other deviations from the reference design affect the uncertainty of the
determination of sound power levels of AMDs is not known.

5.2 Test plenum: main assembly
The test plenum shall consist of an airtight chamber constructed with a frame covered with an airtight
acoustically transparent polyester film, a mounting panel, and an adjustable exit port assembly as shown in
Figure 1. The plenum shall conform to the requirements specified in 5.2.1 to 5.2.6.
5.2.1 Plenum size: Figure 1 shows the dimensions of the full-size plenum.
5.2.2 Covering: Isotropic polyester film of nominal thickness 25 µm to 50 µm. Batten strips may be used
to protect the covering (see Figure 1 and Figure 2).
5.2.3 Frame: Suitable material with nominal size of 50 mm × 50 mm that provides structural integrity for
the plenum. Corner gussets are recommended for wood framing and may be needed for other materials (see
Figure 3). Frame linear dimensions including the thickness of the framing members shall be in scale with the
plenum size.
5.2.4 Frame material: Experience has shown that either a hardwood, such as birch, or aluminium
tubing provides sufficient strength, stiffness and durability and complies with the acoustical performance
requirements outlined in 5.5.
5.2.5 Vibration isolation: The test plenum feet or support should provide vibration isolation of the
plenum from the floor, for any size of plenum. The intent is to break the vibration-transmission path between
the plenum and the floor. Whichever method is chosen, the 0,1 m overall leg height should be maintained for
the full-size plenum (see Figure 1 and Figure 3). The 0,1 m leg height shall be in scale with the plenum size.
5.2.6 Taps for fan static pressure: The pressure ring shall be mounted immediately behind the mounting
panel. The ring should be sized to match the perimeter of the mounting panel (see Figure 4). The perimeter
dimensions of the pressure ring shall be in scale with the plenum size. The tubing diameter and taps do not
scale but remain constant.
5.3 Mounting panel assembly
The mounting panel assembly shall comprise some kind of adapter plate sealed and attached to a reinforced
rubber sheet which, in turn, is sealed and attached to the test plenum frame through the use of aluminium
retaining strips (see Figure 1, Figure 4, and Figure 5). The adapter plate is used to mount the fan securely to
the rubber panel. It may take the form of that shown in Figure 5, which is well suited to axial-flow fans, or
some other form more suitable to the particular air-moving device under test. The adapter plate should not
cause any disturbance to the air flow and should not cause any additional sound radiation other than that
from the air-moving device itself.
The mounting panel assembly (comprising adapter plate and flexible panel) may be replaced by a single
damped plate with comparable cut-outs (but no adapter plate) of specified material without significantly
affecting the airborne sound measurements.
The specification on the plate stock is mobility level (reference: 1 m/N·s) of −45 dB from 25 Hz to 5 000 Hz
when measured in the middle of a plate of dimension 1,0 m with no fan-mounting hole and with the plate
freely suspended by two corners. The mobility level measurement shall be made in accordance with ANSI/
ASA S2.32.
The tolerance on mobility levels is ±8 dB from 25 Hz to 100 Hz, ±4 dB from 100 Hz to 200 Hz and ±2 dB
from 200 Hz to 5 000 Hz. These tolerance limits ensure that the plate has sufficient damping to prevent
excitation of the frame. Such replacement panels are sometimes used in connection with fan vibration
[6]
measurements (which are addressed in ISO 10302-2 ). Using the same mounting panel for sound and
vibration measurements may improve the efficiency of combined tests. If the reference design mounting
panel is replaced, on the basis of impedance testing of the plate material, this shall be stated in the test
report.
The opening of the adapter plate shall conform to the recommendations of the AMD manufacturer. The
openings in the clamp frame and rubber panel shall be larger than the opening in the adapter plate to
minimize disturbance of the airflow. The length, width, and thickness of the aluminium retainer strip as
well as the length and width of the reinforced rubber mounting panel shall be in scale with the plenum size.
The other dimensions, including the panel thickness, do not scale.
5.4 Adjustable exit port assembly
The adjustable exit port assembly shall comprise a fixed aperture plate and a slider (movable sliding plate) to
2 2
provide a continuously variable exit port of area from 0,0 m to 0,2 m for the full-size plenum (see Figure 6
to Figure 8). The exit port maximum area shall be in scale with the square of the linear scale of the plenum.
NOTE The point of operation of the AMD is controlled during a test by adjusting the position of the slider on the
exit port assembly.
5.5 Insertion loss of test plenum
For the purpose of this document, adequacy of the test plenum is evaluated by means of insertion loss of the
test plenum (see 3.2.3).
Within the frequency range of interest (see 3.2.2), the one-third-octave-band insertion loss of the test
+3
plenum shall be not greater than 0 dB and is recommended to be not greater than (0 ± 1,5) dB, when
()
−2
determined in accordance with the procedure specified in steps a) to c).
a) The sound power levels of a sound source (e.g. a loudspeaker) shall be determined twice: once with the
source inside the test plenum and once with the source outside the plenum, but at the same location
in the test room. If insertion loss measurements are made in a free field over a reflecting plane, the
hemispherical microphone array should be centred on the sound power source.
b) Measurement uncertainties can arise if the loudspeaker sound power source is moved relative
to reflective surfaces (floor and mounting panel) between the two sound power determinations.
Accordingly, install the sound power source on the floor. Remove the mounting panel and rotate the
plenum by 90° so that the face normally covered by the mounting panel is parallel to the floor and the
exit port is on the top surface. The plenum can then be lowered or raised vertically to cover or expose
the sound power source without causing movement of the source.
c) The source shall be mounted to ensure that solid body radiation from the sound power source which is
transmitted into the test plenum frame or covering is minimized.
The exit port slider shall be closed during the insertion loss test.
5.6 Instrumentation for static pressure measurement
The fan static pressure developed inside the test plenum by the AMD shall be measured using a pressure
ring (shown in Figure 4). This pressure ring has four taps spaced 90° apart as shown, facing towards the
centre of the discharge of the AMD (in the plane of the ring). The pressure ring should be mounted on the
frame that supports the mounting panel. A pressure line can be brought out of the box by drilling a small,
smooth, burr-free hole through the frame. The fan static pressure should be read on a calibrated pressure
meter.
The manometer or other pressure measuring device used shall have a resolution of 1 % or finer (e.g. 0,5 %)
of maximum fan static pressure.

6 Installation
6.1 Installation of test plenum in test room
The test plenum shall be installed on the floor of a test room, which has been qualified for sound power level
determinations in accordance with ISO 7779:2018, Clause 6 or Clause 7, respectively.
6.2 Direction of airflow
The AMD should preferably be tested when discharging into the test plenum. Exceptions to this airflow
direction can be made to avoid undesirable flow conditions. For example, centrifugal fans or motorized
impellers without scrolls can be tested with the plenum on the inlet.
6.3 Mounting of air-moving device
The AMD shall be mounted on and sealed to the mounting panel assembly specified in 5.3 (either the
rubber sheet with adapter plate and clamp frame or the single damped panel). Additional vibration-isolated
supports, which shall not interfere with the propagation of airborne sound, shall be provided as necessary
to maintain the mounting plane parallel with the face of the test plenum; in particular, such supports can
be required when testing centrifugal fans, especially at low static pressures. In all cases, the mounting
panel assembly shall remain plane with the face of the plenum. For large AMDs, auxiliary support can be
required to prevent the weight of the device from bending or twisting the mounting panel. Such auxiliary
support shall not interfere with the propagation of airborne sound and shall be vibration-isolated from the
air-moving device.
The AMD should be tested for each of its configurations (see Note 2 to 3.1.1).
In some cases, AMDs operating under conditions which keep the plenum exit port completely open can
cause the polyester film panels to flutter or vibrate, creating unwanted noise. In such cases, steps should be
taken to minimize noise due to fluttering or vibration. For example, the mounting panel assembly with the
AMD can be detached from the rest of the plenum and the latter moved out of the way. The mounting panel
assembly should be maintained planar and suspended above the floor of the test room at the same location
as specified in 6.1.
7 Operation of air-moving device
7.1 Input power
7.1.1 Alternating current (AC) air-moving devices
The AMD shall be operated at each rated power line frequency, and within ±1,0 % of either:
a) the rated voltage (if any is stated); or
b) the mean voltage of a stated voltage range (e.g. 220 V for a stated range of 210 V to 230 V).
For power having more than two phases, phase-to-phase voltage variations shall not exceed 1 % of the rated
voltage.
NOTE Though the test procedure of Clause 7 is similar to those of ISO 7779, the tolerance of voltage given here is
much tighter than that in ISO 7779 (i.e., 5 % of the rated voltage).
7.1.2 Direct current (DC) air-moving devices
The AMD shall be operated within ±1 % of the rated nominal voltage.
Additional tests may be run at other voltages (e.g. rated maximum, rated minimum).

7.2 Points of operation (AC and DC air-moving devices)
7.2.1 Required points of operation
For the selection of points of operation, there are the following 2 methods.
Method A of 7.2.2 is, so called conventional method, which defines points of operation as a function of the
maximum flow rate of the AMD of interest.
Method B of 7.2.3 is alternative method, which defines points of operation as a point at the intersection of
the p-q curve of the AMD and the system impedance curve.
In conformity to this document, the requirements of at least, either 7.2.2 and/or 7.2.3 are to be fully satisfied.
7.2.2 Method A (conventional method)
7.2.2.1 Required points of operation
The AMD shall be tested at three points of operation for each of the required line frequencies and voltages
given in 7.1. These points of operation correspond to
a) the adjustable exit port (slider) completely open,
b) 80 % of maximum volume flow rate on the p-q curve, and
c) 20 % of maximum volume flow rate on the p-q curve.
The actual static pressure reading at each point of operation shall be recorded.
NOTE 1 In this document, p-q curve measurement is a prerequisite for acoustical noise measurement. So the
“maximum volume flow rate” means the point on the p-q curve (see 3.3.2), which corresponds to the condition of static
pressure equal to 0. For instance, when the maximum volume flow rate of a fan under test is read as 0,01 m /s from
3 3
the p-q curve, 80 % of maximum volume flow rate means 0,01 m /s × 0,8 = 0,008 m /s.
NOTE 2 Within the framework of this document, a clear distinction is made between “slider completely open” and
“maximum flow rate”. In the previous edition and other conventional standards this was not the case. Condition a)
above, “slider completely open”, was referred to as the “maximum flow rate” or “free delivery” condition. However,
air-flow resistance by the plenum influences the actual point of operation. For example, the three smooth lines near
the abscissa in Figure 9 indicate the system impedance curves of the quarter-scale, half-scale and full-scale plenum
respectively, with slider completely open.
7.2.2.2 Additional points of operation
Additional tests may be run at other points of operation, including the point of maximum overall static
efficiency, to establish the sound power level versus volume flow rate curve. Some AMDs (e.g. small tube-
axial fans) can be unstable when operated near the maximum overall static efficiency point. Tests should not
be conducted at unstable points of operation.
7.2.3 Method B (alternative method)
7.2.3.1 Required points of operation
The AMD shall be tested at point of operation at the intersection of the p-q curve of the AMD and the system
2)
impedance curve of the candidate system (i.e. a functional unit which is expected to install the AMD), for
each of the required line frequencies and voltages given in 7.1. These test points correspond to the actual
points of operation of the candidate system.
2) System impedance curve can be referred to system resistance curve.

7.2.3.2 Additional points of operation
Optionally, the points of operations specified in 7.2.2.1 can be added.
7.2.4 Procedure
Points of operation shall be established as in steps a) to c).
a) The fan static pressure at the designated percentage volume flow rates shall be read from the AMD
aerodynamic performance curve (p-q curve) determined (prior to acoustical noise measurement) in
accordance with ISO 5801 or Annex A, as applicable, with the same direction of airflow.
b) If the ambient atmospheric density during the noise test differs by more than 1 % from that recorded
in accordance with ISO 5801 or Annex A, as applicable, the fan static pressure shall be corrected as
follows:
p
273 +t
 
amb,2
pp=  (5)
s,2s,1  
273 +t p
 2  amb,1
where
is the fan static pressure to be set on the test plenum during acoustical noise measurement, in
p
s,2
pascals;
t is the air-flow temperature during acoustical noise measurement, in degrees Celsius;
p
is the atmospheric pressure during acoustical noise measurement, in kilopascals;
amb,2
p is the fan static pressure during volume flow rate measurement, in pascals;
s,1
t is the air-flow temperature during volume flow rate measurement, in degree Celsius;
p
is the atmospheric pressure during volume flow rate measurement, in kilopascals.
amb,1
c) The slider shall be adjusted to obtain a reading of the fan static pressure, p , within ±1 % of the
s,2
maximum fan static pressure, determined with a pressure-measuring instrument satisfying the
requirements of 5.6.
The fan and the fan static pressure shall be allowed to stabilize at each point of operation.
If measurements are made at the maximum
...