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  • BS 848-2(1985) : 1985

    Superseded A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.
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    FANS FOR GENERAL PURPOSES - METHODS OF NOISE TESTING

    Available format(s):  Hardcopy, PDF

    Superseded date:  25-08-2004

    Language(s):  English

    Published date:  01-01-1985

    Publisher:  British Standards Institution

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    Table of Contents - (Show below) - (Hide below)

    Foreword
    Committees responsible
    Methods
    1. Scope
    2. Definitions
    3. Symbols and units
    4. Test methods, general
    5. Instrumentation
    6. In-duct test methods
    7. Reverberant field test method
    8. Free field and semi-reverberant test method
    9. Conversion rules for sound power levels
    10. Information to be recorded
    11. Information to be reported
    Appendices
    A. Precision of the in-duct method of measurement
    B. Determination of the signal-to-noise ratio of
         sound to turbulence noise in the test duct
    C. Examples of suitable instrumentation systems
    D. Anechoic termination
    E. Reverberation time qualification test and
         evaluation of environmental correction factor K
    F. Absolute comparison qualification test for
         evaluation of environmental correction K
    G. Generalized guide for sound power level prediction
    H. Characteristics and calibration of reference
         sound source
    Tables
    1. Uncertainty in determination of the broad band
         sound power levels
    2. Example of instrument response correction to
         measured sound pressure levels
    3(a) Flow velocity correction C3 for sampling tube in
         outlet side duct
    3(b) Flow velocity correction C3 for sampling tube in
         inlet side duct
    4(a) Modal correction C4 for a sampling tube
    4(b) Modal correction C4 for omnidirectional micro-
         phones
    5(a) Maximum standard deviation
    5(b) Corresponding maximum range of sound pressure
         levels
    6. Coordinates of microphone locations for
         hemispherical measurement surface for type A
         installations and corresponding representative
         surface areas
    7. Coordinates of microphone locations for
         hemispherical measurement surface for type B and C
         installations and corresponding representative
         surface areas
    8. Coordinates of microphone locations for spherical
         measurement surface and corresponding represent-
         ative surface areas
    9. Effect of end reflections
    10. Effect of transitions
    11. Computation of power from pressure measurements
    12. Maximum differences between the sound pressure
         level readings of a microphone fitted with a nose
         cone and of a microphone fitted with a sampling
         tube as a function of the turbulence noise
         suppression triangle Lt of the sampling tube, for
         a minimum signal-to-noise ratio of sound to
         turbulence noise of 5 dB
    13. Turbulence noise suppression triangle Lt of
         typical sampling tube as compared with that of a
         13 mm nose cone
    14. Maximum pressure reflection coefficient
    15. Calibration accuracy for reference sound source
    Figures
    1. Example of frequency response of microphone fitted
         with protection grid as supplied by a manufacturer
    2. Schematic drawing of a typical sampling tube
    3. Limiting dimensions of test ducts, intermediate
         ducts and transitions for type B installations
    4. Limiting dimensions of test ducts, intermediate
         ducts and transitions for type C installations
    5. Limiting dimensions of test ducts, intermediate
         ducts and transitions for type D installations
    6. Test room with whole air circuit within walls
    7. Test room with type A installation
    8. Test room with types B and C installations
    9. End reflection correction
    10. Microphone positions for a hemispherical measure-
         ment surface for type A installation
    11. Microphone positions for a hemispherical measure-
         ment surface for types B and C installations
    12. Microphone positions for spherical measurement
         surface
    13. Examples of anechoic termination
    14. Examples of three catenoidal designs of anechoic
         termination
    15. Examples of inlet anechoic termination (catenoidal)
    16. Example of stepped inlet anechoic termination
    17. Environmental correction K, in dB
    18. Example of determination of a and b for typical
         fan series

    Abstract - (Show below) - (Hide below)

    Describes the acoustic performance of fans designed to operate against a difference of pressure. Used to determine the sound power of a fan combined with an ancillary device such a roof cowl, damper or fan silencer. May be of the axial, centrifugal, mixed flow or other type. Air circulation fans are excluded. The uncertainty of measurement applies primarily to the steady broadband noise.

    Standards Referenced By This Book - (Show below) - (Hide below)

    BS 4856-3(1975) : 1975 METHODS FOR TESTING AND RATING FAN COIL UNITS UNIT HEATERS AND UNIT COOLERS - THERMAL AND VOLUMETRIC PERFORMANCE FOR HEATING AND COOLING DUTIES WITH ADDITIONAL DUCTING
    BS 848-1(1980) : 1980 FANS FOR GENERAL PURPOSES - METHODS OF TESTING PERFORMANCE
    BS 4857-2(1978) : 1978 METHODS FOR TESTING AND RATING TERMINAL REHEAT UNITS FOR AIR DISTRIBUTION SYSTEMS - ACOUSTIC TESTING AND RATING
    BS 4856-4(1978) : 1978 METHODS FOR TESTING AND RATING FAN COIL UNITS UNIT HEATERS AND UNIT COOLERS - ACOUSTIC PERFORMANCE WITHOUT ADDITIONAL DUCTING
    BS 4856-5(1979) : 1979 METHODS FOR TESTING AND RATING FAN COIL UNITS UNIT HEATERS AND UNIT COOLERS - ACOUSTIC PERFORMANCE WITH DUCTING
    BS 4954-2(1978) : 1978 METHODS FOR TESTING AND RATING INDUCTION UNITS FOR AIR DISTRIBUTION SYSTEMS - ACOUSTIC TESTING AND RATING
    BS 4718(1971) : 1971 METHODS OF TEST FOR SILENCERS FOR AIR DISTRIBUTION SYSTEMS
    BS 4856-4(1997) : 1997 METHODS FOR TESTING AND RATING FAN COIL UNITS, UNIT HEATERS AND UNIT COOLERS - DETERMINATION OF SOUND POWER LEVELS OF FAN COIL UNITS, UNIT HEATERS AND UNIT COOLERS USING REVERBERATING ROOMS

    Standards Referencing This Book - (Show below) - (Hide below)

    ISO 2204:1979 Acoustics Guide to International Standards on the measurement of airborne acoustical noise and evaluation of its effects on human beings
    BS 4196-4(1981) : 1981 SOUND POWER LEVELS OF NOISE SOURCES - ENGINEERING METHODS FOR DETERMINATION OF SOUND POWER LEVELS FOR SOURCES IN FREE FIELD CONDITIONS OVER A REFLECTING PLANE
    BS 4196-2(1981) : LATEST SOUND POWER LEVELS OF NOISE SOURCES - PRECISION METHODS FOR DETERMINATION OF SOUND POWER LEVELS FOR DISCRETE FREQUENCY AND NARROW BAND SOURCES IN REVERBERATION ROOMS
    BS 848-1(1980) : 1980 FANS FOR GENERAL PURPOSES - METHODS OF TESTING PERFORMANCE
    BS 4196-5(1981) : 1981 SOUND POWER LEVELS OF NOISE SOURCES - PART 5: PRECISION METHODS FOR DETERMINATION OF SOUND POWER LEVELS FOR SOURCES IN ANECHOIC AND SEMI-ANECHOIC ROOMS
    BS 4196-1(1981) : LATEST SOUND POWER LEVELS OF NOISE SOURCES - PRECISION METHODS FOR DETERMINATION OF SOUND POWER LEVELS FOR BROAD BAND SOURCES IN REVERBERATION ROOMS
    BS 848-4(1997) : 1997 FANS FOR GENERAL PURPOSES - PART 4: DIMENSIONS
    BS 4196-6(1981) : 1981 SOUND POWER LEVELS OF NOISE SOURCES - SURVEY METHOD FOR DETERMINATION OF SOUND POWER LEVELS OF NOISE SOURCES
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