ISO 7917:1987

Acoustics — Measurement at the operator's position of airborne noise emitted by brush saws

Specifies a method for measuring the A-weighted and octave-band sound pressure levels of noise emission of portable, hand-held saws for use primarily in forestry which are powered by internal combustion engines.

Acoustique — Mesurage au niveau de l'oreille de l'opérateur du bruit émis par les débroussailleuses

La présente Norme internationale spécifie une méthode de mesurage des niveaux de pression acoustique pondérés A et par bande d'octave, au niveau de l'oreille de l'opérateur, du bruit émis par les débroussailleuses manuelles portatives, utilisées principalement pour la sylviculture et actionnées par les moteurs à combustion interne. Les conditions de fonctionnement au cours du mesurage simulent des conditions normales d'utilisation en forêt. NOTE -- La présente Norme internationale est fondée sur les directives générales de l'ISO 60811); toutefois, pour simuler une situation de fonctionnement normal d'une débroussailleuse, un sol absorbant est spécifié au lieu d'un plan réfléchissant.

General Information

• Status: Withdrawn
• Publication Date: 16-Dec-1987
• Withdrawal Date: 16-Dec-1987
• ICS: 17.140.20 - Noise emitted by machines and equipment
• ICS: 65.060.80 - Forestry equipment
• Technical Committee: ISO/TC 43/SC 1 - Noise
• Drafting Committee: ISO/TC 43/SC 1 - Noise
• Parallel Committee: ISO/TC 23/SC 17 - Manually portable (hand-held) powered lawn and garden equipment and forest machinery
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 04-Feb-2005

Relations

• Revised: ISO 22868:2005 - Forestry machinery — Noise test code for portable hand-held machines with internal combustion engine — Engineering method (Grade 2 accuracy)
• Effective Date: 15-Apr-2008

Standards Content (Sample)

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INTERNATIONAL STANDARD
7917
First edition
1987-12-15
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Acoustics - Measurement at the operator’s Position
of airborne noise emitted by brush saws
Acoustique - Mesurage au niveau de l’oreiile de l’operateur du bruit hmis par les
dkbroussailfeuses
Reference number
ISO 7917: 1987 (E)

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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. Esch 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, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 7917 was prepared jointly by Technical Committees
ISO/TC 43, Acoustics and ISO/TC 23, Trattors and machinery for agriculture and
forestry.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
0 International Organkation for Standardkation, 1987
Printed in Switzerland

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INTERNATIONAL STANDARD ISO 7917 : 1987 (E)
Acoustics - Measurement at the operator’s Position
brush saws
of airborne noise emitted by
4 Acoustic environment
1 Scope and field of application
This International Standard specifies a method for measuring
4.1 Open space
the A-weighted and octave-band Sound pressure levels, at the
operator’s Position, of noise emitted by portable, hand-held
The test site shall be an open space having a radius of at least
brush saws for use primarily in forestry which are powered by
IO m which shall be completely free from obstructions which
internal combustion engines.
might influence the measurement. However, large reflecting
surfaces, such as a fence or a Wall, shall not be closer than a
The operating conditions during measurement simulate normal
radius of 20 m. No person, including the observer, shall ap-
operating conditions in the forest.
proach closer than 2 m to the Operator. The operator’s clothing
shall not be of particularly absorbing or reflecting material. The
NOTE - This International Standard is based on the general guidelines
ground at the centre of the test site shall have good sound-
of ISO 60811); however, to simulate a normal operating Situation of a
absorbent properties and may comprise forest ground, grass or
brush saw, an absorbing ground is specified instead of a reflecting
an equivalent surface. lt should be approximately flat. The
plane.
ground may be covered in Snow, but not ice.
2 References
4.2 Enclosed space
ISO 266, Acoustics - Preferred frequencies for measuremen ts.
IVleasurements may also be carried out in a large building, pro-
vided that it tan be proved that they are in accordance, to
ISO 8893, Forestry machinery - Portable brush saws -
within + 1 dB, with the levels measured under the conditions
Engine performante and fuel consumption.2)
given in 4.1 for one-third octave bands of noise in the frequen-
cy range from 50 to IO 000 Hz.
IEC Publication 225, Octave, half-octave and third-octave band
filters intended for the analysis of Sounds and vibra tions.
4.3 Background noise
IEC Publication 651, Sound level meters.
At the microphone Position, the background noise (including
wind noise) measured as the A-weighted Sound pressure level
3 Measured quantities
and in each octave band, as appropriate, shall be at least IO dB
below the Sound pressure levels measured during the test.
3.1 The values measured shall be A-weighted Sound pressure
levels, in decibels, determined with the frequency-weighting
characteristic A and the time-weighting characteristic S as
4.4 Ambient conditions
defined in IEC Publication 651.
Environmental conditions (humidity, temperature, Vibration,
stray fields, etc.) shall be within the limits specified by the
3.2 Spectral analysis is optional. When required, octave-
manufacturers of the measuring equipment and of the brush
band Sound pressure levels, in decibels, shall be measured in
saw under test.
the eight bands having centre frequencies from 63 to 8 000 Hz.
- Guidelines for the prepara tion o f tes t Codes o f engineering grade requiring
1) ISO 6081, Acoustks - Noise emitted by machinery and equipment
noise measuremen ts at the Operator3 Position.
2) At present at the Stage of draft.
1

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ISO 7917 : 1987 (E)
I be in the range from If alternative measuring equipment, including, for example, a
The ambient air tempera ture shal
OC; the wind Speed sh all be less than 5 m/s. tape recorder, is used, the tolerantes of the whole measuring
-10 to + 30
System shall not exceed the tolerantes of the relevant clauses
NOTE - This requirement is intended to ensure that the of IEC Publication 651 for a type 1 instrument in the frequency
meteorological conditions do not prevent the accuracy levels specified range from 50 to 10 000 Hz.
in 4.2 and 8.1 from being attained.
NOTES
1 If a tape recorder is used as part of the measuring equipment, it
may be necessary to include suitable weighting networks for recording
5 Saw conditions and testing material
and reproduction to provide an adequate signal-to-noise ratio over the
whole frequency range of interest.
5.1 General conditions
2 Care should be taken, particularly when a microphone with a
diameter of more than 13 mm is used, to ensure that the directional
Measurements shall be carried out on a normal production
characteristics of the microphone do not lead to errors (see clause 7). It
brush saw having a Standard configuration with the cutting
is recommended that, when necessary, a random incidence adaptor be
equipment provided by the manufacturer. The engine shall be
used to ensure that the omnidirectionality is not worse than that of a
run in and warmed up before the test is commenced, the car-
type 1 Sound level meter as specified in IEC Publication 651.
burettor and ignition timed in accordance with the instructions
3 Care should be taken to insulate the microphone from vibrations
of the manufacturer, and the cutting equipment sharpened for
which could affect the measurements. Care should also be exercised to
best cutting Performance in accordance with the manufacturer’s
avoid introducing acoustical noise (e.g. noise due to the microphone
recommendations.
rubbing against the operator’s clothing) or electrical noise (e.g. due to
a flexing cable) that could inter-fere with the measurements.
5.2 Harness adjustment and attachment (sec the
figure)
6.2 Frequency analysis
Working on the assumption that a man is 1 750 fr 20 mm tall,
Measurement of the Sound frequency spectrum, if required,
the following adjustments shall be made before the test :
shall be carried out using a frequency analyser fitted with filters
in accordance with IEC Publication 225. The centre frequencies
-
the harness shall be
...