Reference number
ISO 2151:2004(E)
© ISO 2004
INTERNATIONAL
STANDARD
ISO
2151
Second edition
2004-02-01
Acoustics — Noise test code for
compressors and vacuum pumps —
Engineering method (Grade 2)
Acoustique — Code d'essai acoustique pour les compresseurs et les
pompes à vide — Méthode d'expertise (classe de précision 2)
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2004
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing 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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2004 – All rights reserved
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
© ISO 2004 – All rights reserved iii
Contents Page
Foreword............................................................................................................................................................ iv
Introduction ........................................................................................................................................................ v
1 Scope...................................................................................................................................................... 1
2 Normative references ........................................................................................................................... 2
3 Terms and definitions........................................................................................................................... 2
4 Sound power level determination ....................................................................................................... 5
4.1 General ................................................................................................................................................... 5
4.2 Uncertainty............................................................................................................................................. 6
4.3 Test arrangement .................................................................................................................................. 6
5 Emission sound pressure level determination at the work station ................................................. 7
5.1 Work station .......................................................................................................................................... 7
5.2 Determination of LpWSA from LWA...................................................................................................... 8
5.3 Method for determination of LpWSA when LWA is not to be determined ........................................ 9
6 Mounting, loading and operating conditions of compressor or vacuum pump during
noise tests.............................................................................................................................................. 9
6.1 General ................................................................................................................................................... 9
6.2 Mounting ................................................................................................................................................ 9
6.3 Loading and operating conditions ...................................................................................................... 9
7 Test report............................................................................................................................................ 10
8 Declaration and verification of noise emission values ................................................................... 10
Annex A (informative) Example test reports.................................................................................................. 11
Annex B (informative) Model form for declared noise emission values..................................................... 17
Annex C (normative) Parallelepiped measurement surface ........................................................................ 18
Annex D (normative) Hemispherical measurement surface ........................................................................ 20
Annex E (informative) Examples of reference box for different machines................................................. 22
Bibliography ..................................................................................................................................................... 25
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
iv © ISO 2004 – All rights reserved
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 2151 was prepared by Technical Committee ISO/TC 118, Compressors, pneumatic tools and pneumatic
machines, Subcommittee SC 6, Air compressors.
This second edition cancels and replaces the first edition (ISO 2151:1972), which has been technically revised.
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
© ISO 2004 – All rights reserved v
Introduction
The noise test code presented by this International Standard describes methods for determining and
presenting the acoustical characteristics of compressors and vacuum pumps, i.e. the total noise level from the
compressor or vacuum pump expressed as sound power level, or the emission sound pressure level at the
work station or other specified positions.
Based on current industry practice, this noise test code requires the compressor or vacuum pump under test
to be run under conditions representing the noisiest operation in typical usage — full-load for compressors
and off-load for vacuum pumps.
It needs to be noted that operators' exposure to noise depends upon the characteristics of individual
applications and environmental factors beyond the control of the manufacturers of compressors and vacuum
pumps.
This International Standard does not give requirements for octave band analysis, however, where there is an
interest this can be undertaken.
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
INTERNATIONAL STANDARD ISO 2151:2004(E)
© ISO 2004 – All rights reserved 1
Acoustics — Noise test code for compressors and vacuum
pumps — Engineering method (Grade 2)
1 Scope
This International Standard specifies methods for the measurement, determination and declaration of the
noise emission from portable and stationary compressors and vacuum pumps. It prescribes the mounting,
loading and working conditions under which measurements are to be made, and includes measurement or
determination of the noise emission expressed as
the sound power level under specified load conditions,
the emission sound pressure level at the work station under specified load conditions.
It is applicable to
compressors for various types of gases,
oil-lubricated air compressors,
oil-flooded air compressors,
water injected air compressors,
oil-free air compressors,
compressors for handling hazardous gases (gas compressors),
compressors for handling oxygen,
compressors for handling acetylene,
high-pressure compressors [over 4 Mpa (40 bar)],
compressors for application at low inlet temperatures, i.e. below 0 °C,
large compressors (over 1 000 kW input power),
portable and skid-mounted air compressors, and
rotary positive displacement blowers and centrifugal blowers and exhausters in applications u 0,2 MPa
(u 2 bar).
It is not applicable to
compressors for gases other than acetylene having a maximum allowable working pressure of less than
0,5 bar/0,05 MPa,
refrigerant compressors used in refrigerating systems or heat pumps,
hand-held portable compressors.
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
2 © ISO 2004 – All rights reserved
2 Normative references
The following referenced documents are indispensable 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 3744:1994, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Engineering method in an essentially free field over a reflecting plane
ISO 4871:1996, Acoustics — Declaration and verification of noise emission values of machinery and
equipment
ISO 9614-1:1993, Acoustics — Determination of sound power levels of noise sources using sound intensity —
Part 1: Measurement at discrete points
ISO 9614-2:1996, Acoustics — Determination of sound power levels of noise sources using sound intensity —
Part 2: Measurement by scanning
ISO 11201:1995, Acoustics — Noise emitted by machinery and equipment — Measurement of emission
sound pressure levels at a work station and at other specified positions — Engineering method in an
essentially free field over a reflecting plane
ISO 11202:1995, Acoustics — Noise emitted by machinery and equipment — Measurement of emission
sound pressure levels at a work station and at other specified positions — Survey method in situ
ISO 11203:1995, Acoustics — Noise emitted by machinery and equipment — Determination of emission
sound pressure levels at a work station and at other specified positions from the sound power level
IEC 61672-1:2002, Electroacoustics — Sound level meters — Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
compressor
machine which compresses air, gases or vapours to a pressure higher than the inlet pressure
NOTE A compressor comprises the bare compressor itself, the prime mover and any component or device supplied
with the compressor.
3.2
vacuum pump
device for creating, improving and/or maintaining vacuum
NOTE A vacuum pump comprises the bare pump, the prime mover and any component or device supplied with the
vacuum pump.
3.3
emission
airborne sound radiated by a well-defined noise source (e.g. the machine under test) under specified
operating and mounting conditions
NOTE 1 Adapted from ISO 11203:1995.
NOTE 2 Noise emission values can be incorporated in a product label and/or published in a product specification. The
basic noise emission descriptors are the sound power level of the product itself and the emission sound pressure levels at
the work station and at other specified positions in the vicinity of the product (if any).
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
ISO 2151:2004(E)
© ISO 2004 – All rights reserved 3
3.4
emission sound pressure
p
sound pressure, expressed in pascals, at a specified position near a noise source, when the source is in
operation under specified operating and mounting conditions on a reflecting plane surface, corrected for
background noise and reflections from room surfaces other than the plane over which the machine under test
is placed
NOTE Adapted from ISO 11203:1995.
3.5
emission sound pressure level
Lp
ten times the logarithm to the base 10 of the ratio of the square of the emission sound pressure to the square
of the reference sound pressure, expressed in decibels, and measured with a particular time weighting and a
particular frequency weighting selected from those defined in IEC 61672-1:2002
EXAMPLE A-weighted emission sound pressure level, LpA.
NOTE 1 The reference sound pressure is 20 µPa.
NOTE 2 LpA levels are established as LpAeqT time-averaged sound pressure levels measured with an integrating-
averaging sound level meter meeting the requirements of IEC 61672-1:2002. LpAeqT is usually abbreviated to LpA. For
further details of LpAeqT see ISO 3744:1994, 3.2.1.
NOTE 3 Adapted from ISO 11203:1995.
3.6
sound power
W
rate per unit time, expressed in watts, at which airborne sound energy is radiated by a source
[ISO 3744:1994]
3.7
sound power level
LW
ten times the logarithm to the base 10 of the ratio of the sound power radiated by the source under test to the
reference sound power, expressed in decibels
NOTE 1 The frequency weighting or the width of the frequency band must be indicated. For example, A-weighted
sound power level LWA.
NOTE 2 The reference sound power is 1 pW (1 pW = 10−12 W).
NOTE 3 Adapted from ISO 3744:1994.
3.8
sound intensity
product of the sound pressure at a point and the associated particle velocity
NOTE 1 It is a vectorial quantity.
NOTE 2 See ISO 9614-1 and ISO 9614-2 for further guidance on sound intensity.
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
4 © ISO 2004 – All rights reserved
3.9
partial sound power
Pi
time-averaged rate of flow of sound energy through an element (segment) of a measurement surface, given
by
ni i i i iP I S I S= × = ×
GG
where
Ini is the signed magnitude of the normal sound intensity component measured at position i on the
measurement surface;
Si is the area of the segment of surface associated with point i.
3.10
background noise correction
K1
correction term to account for the influence of background noise on the surface sound pressure level,
expressed in decibels
NOTE 1 K1 is frequency dependent.
NOTE 2 The correction in the case of A-weighting is denoted K1A.
NOTE 3 Adapted from ISO 3744:1994.
3.11
environmental correction
K2
correction term to account for the influence of reflected or absorbed sound on the surface sound pressure
level, expressed in decibels
NOTE 1 K2 is frequency dependent.
NOTE 2 The correction in the case of A-weighting is denoted K2A.
NOTE 3 Adapted from ISO 3744:1994.
3.12
reference box
hypothetical surface which is the smallest rectangular parallelepiped that just encloses the source and
terminates on the reflecting plane
[ISO 3744:1994]
3.13
measurement surface
hypothetical surface of area S, enveloping the source, on which the measurements are made
NOTE The measurement surface terminates on the reflecting plane.
3.14
measurement distance
distance, d, from the reference box to the parallelepiped measurement surface, or radius, r, of the
hemispherical measurement surface
NOTE Adapted from ISO 3744:1994.
Copyright International Organization for Standardization
Reproduced by IHS under license with ISO
Not for ResaleNo reproduction or networking permitted without license from IHS
-
-
`
`
,
`
`
,
-
`
-
`
,
,
`
,
,
`
,
`
,
,
`
-
-
-
ISO 2151:2004(E)
© ISO 2004 – All rights reserved 5
3.15
noise emission declaration
information on the noise emitted by the machine given by the manufacturer or supplier in technical documents
or other literature concerning noise emission values
3.16
uncertainty
K
value of the total uncertainty associated with a measured noise emission value and the production, expressed
in decibels
[ISO 4871:1996]
NOTE See also 4.2.
3.17
declared dual-number noise emission value
L, K
noise emission value, L, and its associated uncertainty, K, given in the noise emission declaration
NOTE 1 The symbols used are
A-weighted sound power level, LWAd, with uncertainty, KWAd, and
A-weighted emission sound pressure level, LpAd, with uncertainty, KpAd.
NOTE 2 Adapted from ISO 4871:1996.
3.18
work station
position in the vicinity of the compressor or vacuum pump under test, intended for the operator
NOTE 1 For the purposes of this International Standard, this is the surface enveloping the machine on test at a
distance of 1 m from the reference box (see 3.12).
NOTE 2 Adapted from ISO 11203:1995.
3.19
A-weighted emission sound pressure level at the work station
LpWSA
energy average of the A-weighted emission sound pressure levels at the work station
4 Sound power level determination
4.1 General
The sound power level s