BRUEL & KJAER 4184-A Guide

Technical
Documentation
Weatherproof Microphone Unit Type 4184-A
for Hand-held Analyzer
Types 2250, 2250-L and 2270
Supplement to Instruction Manual BE1712
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
ËBE-1843---,Î
English BE1843–12

BE184312 March 2012
Weatherproof Microphone Unit
Type 4184-A
for Hand-held Analyzer
Types 2250, 2250-L and 2270
Type 2250, from Hardware Version 1.1
Type 2250-L, from Hardware Version 2.0
Type 2270, from Hardware Version 3.0
Supplement to Instruction Manual
BE 1712

Copyright 2006 – 2012, 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 IEC61010 –1 and EN61010– 1 Safety Require-
ments for Electrical Equipment for Measurement, Control and Laboratory Use. This manual contains infor-
mation 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

Table of Contents
CHAPTER 1
Introduction.......................................................................................................................................... 1
1.1 About This Supplement............................................................................................................................. 1
1.2 System Overview....................................................................................................................................... 1
CHAPTER 2
Information Required by the Standards ............................................................................................ 3
2.1 Introduction................................................................................................................................................ 3
2.2 Mounting and Placing the Microphone...................................................................................................... 3
2.4 Calibration ................................................................................................................................................. 4
2.7 Measuring at Low Static Pressure............................................................................................................. 4
CHAPTER 3
Conformance Testing.......................................................................................................................... 5
3.1 Introduction................................................................................................................................................ 5
3.2 Mounting for Acoustical Tests ................................................................................................................... 5
3.3 Periodic Testing of Acoustical Frequency Responses .............................................................................. 5
3.4 Mounting for Mechanical Vibrations Tests................................................................................................. 5
3.5 Electrical Substitute for Microphones........................................................................................................ 6
CHAPTER 4
Specifications ...................................................................................................................................... 7
4.1 Specifications ............................................................................................................................................ 7
4.4 Reference Conditions for Acoustic Calibration.......................................................................................... 7
4.5 Microphone................................................................................................................................................ 7
4.7 Directional Responses............................................................................................................................. 10
4.8 Self-generated Noise............................................................................................................................... 13
4.9 Measuring Ranges .................................................................................................................................. 17
APPENDIX A
Tables ................................................................................................................................................. 23
A.2 Free-field Frequency Responses ............................................................................................................ 23
A.3 Diffuse-field Frequency Responses......................................................................................................... 26
A.4 Free-field Frequency Responses for Diffuse-field Calibrated Instruments.............................................. 27
A.5 Directional Responses............................................................................................................................. 28
A.6 Periodic Testing of Acoustical Frequency Responses ............................................................................ 35
APPENDIX D
Using Microphone Type 4184-A ....................................................................................................... 37
D.1 Mount Pistonphone Type 4228 onto Type 4184-A.................................................................................. 37
D.2 Mount Multifunction Acoustic Calibrator Type 4226 onto Type 4184-A................................................... 38
D.3 Mount Electrical Substitute for Microphones on the Built–in Microphone Preamplifier ........................... 40
INDEX........................................................................................................................................................................... 43

1
Chapter 1
Introduction
1.1 About This Supplement
This document is a supplement, to Instruction Manual for Hand-held Analyzer Types 2250, 2250-L and
2270 BE 1712. It provides the information relevent when Hand-held Analyzer Type 2250, 2250 L or 2270
is configured with Weatherproof Microphone Unit Type 4184-A.
The combination of Weatherproof Microphone Unit Type 4184-A and the hand-held analyzer is intended
for outdoor use where a weatherproof microphone solution is needed.
The numbering of chapters, sections, figures and tables in this supplement corresponds to
Instruction Manual BE 1712. This supplement only contains content that is different from the
instruction manual and is specific to this microphone configuration. The other chapters, sections,
figures and tables should be read in Instruction Manual BE 1712.
Also see section 1.1 of the instruction manual.
1.2 System Overview
1.2.4 Hardware Setup
This section provides an overview of the additional hardware components used when the analyzers are
configured with Weatherproof Microphone Unit Type 4184-A. The other hardware components can be
found in Instruction Manual BE 1712, section 1.2.4.
NOTE:
• Only one Weatherproof Microphone Unit Type 4184-A can be connected to Type 2270
• Weatherproof Microphone Unit Type 4184-A is calibrated with Brüel & Kjær Pistonphone
Type 4228, which has a calibration frequency of 251.2 Hz and a calibration level of approximately
124 dB
• Weatherproof Microphone Unit Type 4184-A includes the Microphone Preamplifier Type ZE-0773
• Weatherproof Microphone Unit Type 4184-A is specified for two reference directions. In the user
interface they are selected as two different microphones and are called: 4184-A 0° (Top) and 4184-A
90° (Side)
– 4184-A 0° (Top)’s reference direction is defined as the inward direction toward the Microphone
Reference Point on the microphones rotational axis coming from the opposite direction of the
electrical output
– 4184-A 90° (Side)’s reference direction is defined as the inward direction toward the Microphone
Reference Point perpendicular to the microphones rotational axis
• Weatherproof Microphone Unit Type 4184-A has a built-in Windscreen and is therefore not specified
without the Windscreen

Weatherproof Microphone Unit Type 4184-A – Supplement to Instruction Manual BE 17122
• Weatherproof Microphone Unit Type 4184-A cannot be mounted directly onto the analyzer. It is
always connected through an extension cable
• Weatherproof Microphone Unit Type 4184-A is not specified together with Outdoor Microphone Kit
UA-1404
Table 1.1
Additional
hardware
components
needed
for conformance
testing of
the analyzers
configured with
Type 4184-A
Quantity Brüel & Kjær Type/Part
Number Description
1 Type 4184-A Weatherproof Microphone Unit
1 WA-0302-C Electrical Substitute for Microphone cartridge, 18 pF
1 DB-4237 Fixture for WA-302-C
1 UA-1732 Fixture for calibration assembly
1 DB-4199 Calibration Adaptor
1 210411 Adapter for hose, EMC tests
1 Type 4228 Pistonphone

3
Chapter 2
Information Required by the Standards
2.1 Introduction
This chapter contains detailed information required by the standards to be described in the
Instruction Manual.
2.2 Mounting and Placing the Microphone
Weatherproof Microphone Unit Type 4184-A must be connected to the analyzer with Microphone Cable
AO-0697-D-100. The microphone cannot be mounted directly onto the analyzer.
Weatherproof Microphone Unit Type 4184-A is designed to operate mounted vertically with the bird
spikes pointing upwards. The microphone should not be mounted outdoors with other orientations.
Weatherproof Microphone Unit Type 4184-A can be mounted on a pipe with Pole Adapter DB-3068. The
adapter has a female thread that fits onto the male thread of standard 1.5opening diameter water pipes
(ISO 228-1 G1). The mounting ring of the microphone unit is screwed onto the pole adapter.
The microphone can also be mounted on a tripod with Tripod Adaptor UA-1112. The mounting ring of the
microphone unit is screwed onto the tripod adaptor.
The cable must be fed through the pipe or the hole in the tripod adaptor. Connect the cable to the
microphone, mount the microphone on the adaptor and secure it with the mounting ring.
The position of the sound opening of the microphone unit (the Microphone Reference Point) is 118 mm
above the bottom of the windscreen mounting thread.
The microphone must be placed away from shielding, reflecting, or absorbing objects. In a diffuse sound
field, absorbing objects will reduce the measured sound levels. In a free sound field, reflecting objects can
change the measured sound levels. Typically, the sound level 0.5 m from a plain reflecting wall is 3 dB
higher than if there was no wall.
The operator of the system may be personally shielding, absorbing, and reflecting, and the operator can
also be an additional noise source.
The optimum position for the microphone is best found by trying different positions and observing the
resulting sound levels.

Weatherproof Microphone Unit Type 4184-A – Supplement to Instruction Manual BE 17124
2.4 Calibration
The procedures for calibrating the analyzer can be found in User Manual for Hand-held Analyzer
Types 2250 and 2270 BE 1713, User Manual for Hand-held Analyzer Type 2250-L BE 1766, and in
appendix D.1 of this manual.
Weatherproof Microphone Unit Type 4184-A should be calibrated with Brüel & Kjær Pistonphone
Type 4228. Type 4228 is a class LS calibrator as specified in International Standard IEC 60942, Electro-
acoustics Sound Calibrators. The nominal frequency and sound pressure level of Type 4228 are 251.2 Hz
and 124 dB re. 20 Pa, respectively. The sound pressure level in Type 4228 is proportional to the static
pressure; therefore, the procedure in the User Manual for Pistonphone Type 4228 BE 1094 for compen-
sating for the static pressure should be followed.
The procedure for the calibration necessary for the electrical tests during conformance testing can be
found in section 3.5.
While performing the calibration procedures, the analyzer is automatically checked for its ability to
perform the measurements.
2.7 Measuring at Low Static Pressure
The frequency response of the microphone depends on the static pressure. Using a sound level calibrator
to adjust the sensitivity of a Sound Level Meter at the calibration check frequency, 251.2 Hz, provides no
information on the influence of static pressure on frequency response.
Conformance to the specified standards ensures that the system measures within the standard’s tolerances,
in the range from 85 kPa to 108 kPa. In the range of 65 kPa to 108 kPa, the change of frequency response
relative to the response at 251.2 Hz will be less than 0.8 dB.
At the calibration check frequency, the microphone is rather insensitive to variations in the static pressure.
However, Pistonphone Type 4228 is sensitive to variations in the static pressure. Therefore, the procedure
in its manual for compensating for the static pressure should be followed, see section 2.4.