BRUEL & KJAER 4204 User manual

Technical
Documentation
HEADQUARTERS: Brüel&Kjær Sound & Vibration Measurement A/S · DK-2850 Nærum · Denmark
Telephone: [phone] · Fax: [phone] · www.bksv.com · [e-mail]
Local representatives and service organisations worldwide
Reference Sound Source Type 4204
English BE0105–15
User Manual
ËBE-0105---bÎ

BE0105−15 April 2013
Reference Sound Source
Type 4204
User Manual

Copyright 2013, Brüel&Kjær Sound & Vibration Measurement A/S
All rights reserved. No part of this publication may be reproduced or distributed in any form, or
by any means, without prior written consent from Brüel & Kjær Sound & Vibration Measurement
A/S, Nærum, Denmark
Safety Considerations
This apparatus has been designed and tested in accordance with IEC/EN 61010 – 1 and
ANSI/UL 61010 – 1 Safety Requirements for Electrical Equipment for Measurement,
Control and Laboratory Use. This manual contains information and warnings which must be
followed to ensure safe operation and to retain the apparatus in safe condition. Special note should
be made of the following:
Safety Symbols
The apparatus will be marked with this symbol when it is important that you refer to the
associated warning statements given in the manual.
Protective Earth Terminal Hazardous Voltage
Explosion Hazard
The equipment is not designed to be used in potentially explosive environments. It should not be
operated in the presence of flammable liquids or gases.
Warnings
• Switch off all power to equipment before connecting or disconnecting their digital interface.
Failure to do so could damage the equipment
• Whenever it is likely that the correct function or operating safety of the apparatus has been
impaired, it must be made inoperative and be secured against unintended operation
• Any adjustment, maintenance and repair of the open apparatus under voltage must be
avoided as far as possible and, if unavoidable, must be carried out only by trained service
personnel
• Do not dispose of electronic equipment or batteries as unsorted municipal waste
• It is your responsibility to contribute to a clean and healthy environment by using
the appropriate local return and collection systems
• Hazardous substances in electronic equipment or batteries may have detrimental
effects on the environment and human health
• The symbol shown to the left indicates that separate collection systems must be used
for any discarded equipment or batteries marked with that symbol
• Waste electrical and electronic equipment or batteries may be returned to your
local Brüel & Kjær representative or to Brüel & Kjær Headquarters for disposal

Contents
CHAPTER 1
Introduction......................................................................................................... 1
1.1 About This Manual............................................................................................... 1
1.2 Reference Sound Source Type 4204................................................................... 1
CHAPTER 2
Operation............................................................................................................. 5
2.1 Connection of Mains Supply................................................................................ 5
2.2 Sound Power Measurements............................................................................... 6
2.3 Sound Absorption Measurements...................................................................... 12
2.4 Sound Insulation Measurements ....................................................................... 13
CHAPTER 3
Characteristics.................................................................................................. 17
3.1 Frequency Characteristics................................................................................. 17
3.2 Factory Calibration............................................................................................. 18
3.3 Directional Characteristics................................................................................. 18
3.4 Influence of Rotational Speed............................................................................ 20
3.5 Acoustical Effect of Barometric Pressure........................................................... 22
3.6 Acoustical Effect of Ambient Temperature......................................................... 23
3.7 Field Calibration................................................................................................. 23
3.8 Influence of Reflecting Plane............................................................................. 25
3.9 Influence of The Environment............................................................................ 25
3.10 Carrying Case WE-0268.................................................................................... 27
3.11 Service and Repair ............................................................................................ 27
CHAPTER 4
Specifications................................................................................................... 29
INDEX................................................................................................................... 33

1
Chapter 1
Introduction
1.1 About This Manual
This manual describes Reference Sound Source Type 4204, provides setup, input/output
connection, and basic measurement start-up instructions and power options. The aim is to
enable you to get familiar with the system, while preparing it for use.
Fig.1.1
Reference Sound Source
Type 4204
1.2 Reference Sound Source Type 4204
Reference Sound Source Type 4204 is a calibrated source of sound power with very well
defined operating characteristics and a predictable performance. It is rugged, compact and
stable, and is therefore suitable for both field and laboratory use.
Type 4204 is intended for use as a reference sound source for determination of the sound power
output of equipment by the various comparison methods, including the method described in
ISO 3741, and by the survey methods described in ISO 3747.
120457

Reference Sound Source Type 4204 — User Manual2
Type 4204 is also used for measuring environmental correction K2when determining sound
power according to ISO 3744. It is also useful in the field of building acoustics to determine the
sound absorption and sound insulation of a room.
The reference sound source consists essentially of a specially designed centrifugal fan driven
by a powerful asynchronous motor. The motor is an external rotor type, and due to its high
moment of inertia, it has a very constant speed of rotation. The motor is mounted on a cast
aluminium base, shaped to minimize reflections. The complete assembly of motor and fan is
within a cylindrical safety grid fitted with two carrying handles.
The directional characteristic of the reference sound source in the vertical plane varies less than
6 dB for any frequency in the range 100 Hz to 10 kHz (measured in 1/3-octaves) – see
section 3.3. In the horizontal plane, the variation is less than 0.2 dB for frequencies up to
10 kHz (measured in 1/3-octaves). The reference sound source fulfils the requirements for
reference sound sources as stated in ISO 3741, ISO 3747, ISO 6926 and ANSI S12.5. The use
of a reference sound source in noise and sound power measurements on machines is also
described in DIN 45635.
The reference sound source has a frequency range of 100 Hz to 20 kHz. In the range from
100 Hz to 10 kHz, the acoustic power output is greater than 70 dB re 1 pW in any 1/3-octave
frequency band. The A-weighted output is typically 91 dB (50 Hz line frequency) and 95 dB
(60 Hz line frequency). Fig.1.2 shows a typical 1/3-octave frequency response curve of the
Type 4204.
Fig.1.2 Typical sound power spectrum of the Type 4204
901108/1
Sound Power Level of 4204 (dB re 1 pW)
80
100 200 500 1k 2k 5k 10k 20k
75
70
85
Frequency (Hz)
A-weighted level for
60 Hz line freq. and
115 V line volt = 96.0 dBA
A-weighted level for
50 Hz line freq. and
220 V line volt = 91.7 dBA

CHAPTER 1
Introduction 3
Each reference sound source is individually calibrated and, as standard, a calibration certificate
is supplied showing the sound power output from 100 Hz to 20 kHz at 230 V/50 Hz and
115 V/60 Hz operating voltages. Temperature, barometric pressure, humidity and rotational
speed are all given on the calibration certificate. The maximum interval between successive
calibration is 24 months. If there are signs of physical damage to Type 4204, then a
recalibration is recommended.
In the field, the sound power produced may differ from the calibrated value. Changes in mains
supply line voltage and frequency, ambient pressure, and temperature all affect the rotational
speed of Type 4204. In addition, changes in ambient pressure and temperature alter the specific
acoustic impedance of the air, also changing the sound power. Once the values are measured,
however, simple formulae can be used to calculate the correct sound power levels from the
values given on the calibration certificate.

Reference Sound Source Type 4204 — User Manual4