BS 848-2.5(2003) : 2003

Foreword
Introduction
1 Scope
   1.1 General
   1.2 Types of sound source
2 Normative references
3 Terms, definitions and symbols
4 Uncertainty of the measurement method
5 Test facilities and instrumentation
   5.1 General requirements
   5.2 Duct specifications
   5.3 Instrumentation
   5.4 System calibration
6 Test arrangement
   6.1 Sampling tube mounting
   6.2 Microphone position
   6.3 Operating condition control equipment
7 Test procedure
   7.1 Operating conditions
   7.2 Sound pressure level readings
   7.3 Measurements with and without flow straightener on
        the outlet side
   7.4 Inlet side measurements - Large fans: installation
        category D (according to ISO 5801:1997)
8 Calculations
   8.1 Average sound pressure level
   8.2 Sound power level
9 Information to be recorded
10 Information to be reported
Annex A (normative) Determination of the combined mean flow
        velocity and modal correction C[3,4]
Annex B (normative) Determination of the signal-to-noise ratio
        of sound vs. turbulent pressure fluctuation in the test
        duct
Annex C (normative) Computational procedures for calculating the
        A-weighted sound power level from one-third-octave-band
        sound power levels
Annex D (informative) Example of calculation of C[3,4] for a
        given duct diameter and mean flow velocity
Annex E (informative) Guidelines for the design and construction
        of an anechoic termination
Annex F (informative) Evaluation of performance of anechoic
        terminations
Annex G (informative) Sampling tube information
Annex H (informative) Test method for small ducted fans
Annex I (informative) Test method for large ducted fans
Annex J (informative) Measurement of the swirl component
Bibliography

Gives a method for testing ducted fans and other air-moving devices to determine the sound power radiated into an anechoically terminated duct on the inlet and/or outlet side of the equipment.