1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 4856 : Part 4 : 1997 I
2、CS 17.140.20; 91.140.20; 91.140.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Methods for Testing and rating fan coil units, unit heaters and unit coolers Part 4. Determination of sound power levels of fan coil units, unit heaters and unit coolers using reverberation room
3、sBS 4856 : Part 4 : 1997 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 September 1997 BSI 1997 First published January 1978 Second edition July 1997 The following B
4、SI references relate to the work on this standard: Committee reference RHE/6 Draft for comment 95/717445 DC ISBN 0 580 27607 4 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Te
5、chnical Committee RHE/6 to Subcommittee RHE/6/1, upon which the following bodies were represented: HEVAC Association University of Portsmouth Co-opted MembersBS 4856 : Part 4 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 Method 1 Scope 1 2 Norma
6、tive references 1 3 Definitions 1 4 Test facility, instrumentation and procedures 1 5 Installation and operation of equipment to be tested 2 6 Information to be reported 3 Annex A (informative) Bibliography 8 Tables 1 Acoustic test requirements 2 2 Uncertainty in determining sound power levels 3 Fig
7、ures 1 Typical test installation for a wall-mounted unit 4 2 Typical test installation for a ducted unit 5 3 Typical test installation for the open inlet and case radiated noise test 6 4 Typical test installation for the case radiated noise test 7 List of references Inside back coverii BSI 1997 BS 4
8、856 : Part 4 : 1997 Foreword This revision has been prepared by Technical Subcommittee RHE/6/1, and supersedes BS 4856 : Part 4 : 1978 and BS 4856 : Part 5 : 1979, which are both withdrawn. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages
9、 This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. BSI 1997 1 BS 4856 : Part 4 : 1997 Introduction This British Standard specifies a method for determining the sound power levels of fan coil units, unit heaters and unit
10、 coolers, in a reverberation room. It is based on BS 4196 : Part 1 and BS 4196 : Part 2, which describe the acoustic test facilities, instrumentation and procedures to be used for precision grade determination of sound power levels in octave and one-third octave bands of a noise source, having a vol
11、ume less than 1 % of the volume of the reverberation room. 1 Scope This British Standard establishes general rules for acoustic testing of fan coil units, unit heaters and unit coolers, in order to determine sound power levels. This standard is applicable to equipment operating under steady state co
12、nditions. It applies to sources that produce steady broad-band noise, and to sources that may produce significant discrete frequency components or narrow band noises. 2 References 2.1 Normative references This British Standard incorporates, by dated or undated reference, provisions from other public
13、ations. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publications apply to this standard only when
14、 incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This British Standard refers to other publications that provide information or guidance. Editions of these pu
15、blications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this standard, the definitions given in BS 4727 : Part 3 : Group 08 apply, together with the following. 3.1 breakout/ca
16、sing noise The amount of sound energy transmitted via the unit case. 3.2 fan coil unit, unit heater, unit cooler A fluid-to-air heat exchanger apparatus through which air is passed by an electrically powered fan. NOTE. This unit may or may not contain filters. 3.3 frequency range of interest The fre
17、quency range that includes octave bands with centre frequencies between 125 Hz and 8000 Hz, or the one-third octave bands with centre frequencies between 100 Hz and 10000 Hz. 3.4 inlet noise The amount of sound energy transmitted from the inlet of the unit. 3.5 open inlet sound power level The sound
18、 power level transmitted from the inlet of the unit. 3.6 open outlet sound power level The sound power level transmitted from the outlet of the unit. 3.7 outlet noise The amount of sound energy transmitted from the outlet of the unit. 3.8 steady state condition The condition considered to exist, for
19、 test purposes, if the air volume flow rate does not vary by more than 2 % from the mean value during the test. 3.9 unit noise The total amount of sound energy attributable to the unit, equal to the sum of inlet noise, outlet noise, and breakout/casing noise, and applicable to non-ducted units only.
20、 4 Test facility, instrumentation and procedures 4.1 General The acoustic test facilities, instrumentation, and procedures, including room qualification tests, shall be in accordance with BS 4196 : Part 1 or BS 4196 : Part 2. NOTE. BS 4196 : Part 1 and BS 4196 : Part 2 offer two methods for reverber
21、ation room measurements for determining sound power levels: the comparison method uses a reference sound source having a known sound power output, and the direct method uses knowledge of the reverberation time of the room in which the determination is made. If there are substantial variations in the
22、 reverberant room characteristics, due to the presence of the source to be tested, then the test room shall also be qualified according to BS 4196 : Part 1 : 1991 and BS 4196 : Part 2 : 1991, with all the equipment in the room. 4.2 Broad-band noise BS 4196 : Part 1 shall apply if the noise emitted b
23、y the source has a broad-band frequency spectrum without significant narrow-band or discrete frequency components. NOTE. This is typically the case for the aerodynamic sound of the equipment to be tested in accordance with this standard. Broad-band sound power levels shall be determined in one-third
24、 octave bands and shall be reported in both one-third octave bands and octave bands.2 BSI 1997 BS 4856 : Part 4 : 1997 Table 1. Acoustic test requirements Unit type Test type inlet (i) outlet (o) casing (c) (i) + (c) unit open inlet/ open outlet y open inlet/ ducted outlet yy ducted inlet/ ducted ou
25、tlet yyy 4.3 Noise containing discrete-frequency or narrow band components If the noise emitted by the source is likely to contain significant narrow-band or discrete-frequency components, accurate data shall be obtained in accordance with BS 4196 : Part 2. The presence of such frequency components
26、shall be verified following the procedures described in BS 4196 : Part 2. 5 Installation and operation of equipment to be tested 5.1 General Units shall be located on walls or fitted above suspended ceilings, in one of three configurations: a) open inlet, open outlet (vertical unit); b) open inlet,
27、ducted outlet (horizontal unit); c) ducted inlet, ducted outlet (horizontal unit). Before an acoustic test is carried out, the performance characteristics of the unit shall be determined in accordance with BS 848 : Part 1. Measurements of current, fan rotational speed, voltage and pressure drop acro
28、ss the unit shall be noted and used to define the operating test points of the unit. For each configuration, the minimum requirements for acoustic tests shall be as specified in table 1. NOTE. When the equipment is mounted closer than 1 m to one or more reflecting planes, the resultant sound power l
29、evel may be affected by the position of the equipment relative to these planes. 5.2 Test installation of units for measurement of the sound radiated to the reverberation room The unit shall be placed in the reverberation room in an operating position representative of normal usage (figures 1 to 4 il
30、lustrate typical test room arrangements). Requisite distances from the floor, walls and ceilings (as applicable) for normal air circulation shall be provided. The equipment shall be located not less than 1 m from any corner of the room and not on a centre line. The manufacturers fixing instructions
31、shall be followed, if provided, as other mounting arrangements may alter the noise radiation conditions. Where ducting is required, it shall be a rigid duct of the same shape and cross sectional area as the inlet/outlet of the unit, and the ducting shall be lagged where specified (see figures 3 and
32、4). Where inlet or outlet noise is to be determined (see figure 2), the duct shall be a set length of 0.5 m 0.05 m, and terminate flush with the internal wall of the reverberation room. BSI 1997 3 BS 4856 : Part 4 : 1997 Table 2. Uncertainty in determining sound power levels Octave band centre frequ
33、encies One-third octave band centre frequencies Standard deviation A-weighted Hz Hz dB dB 125 100 to 160 3.0 2 250 200 to 315 2.0 2 500 to 4000 400 to 5000 1.5 2 8000 6300 to 10000 3.0 2 5.3 Test procedures NOTE. Acoustic measurements of units are normally carried out at zero heat load. It is not ne
34、cessary, therefore, to connect the heating or cooling medium flows, except when a special test is required. These special tests may give rise to problems with respect to determination of background noise and to establishment of the heat and moisture balance. The integrity and stability of the electr
35、ical supply shall be maintained for the duration of the test to within 2.5 % of nominal voltage. For all units, information obtained from the air performance tests, i.e. air volume, static pressure, fan rotational speed, and applied voltage to the fan, shall be used to determine the test point. For
36、non-ducted units with several rotational speeds, sound tests shall be performed for each speed setting (noting the applied voltage to the fan). For ducted units, sound tests shall be performed at each speed setting (noting the applied voltage to the fan) and for a range of additional external static
37、 pressures. The minimum range of external static pressures shall be 0 %, 30 % and 60 % of the units maximum static pressure development. NOTE. Static pressure loading of the unit should take place outside the reverberation room, in such a way as to minimize the load generated noise. The test procedu
38、re shall be carried out in accordance with BS 4196 : Part 1 or BS 4196 : Part 2. Background noise levels measured without the equipment running shall be at least 6 dB below the sound pressure level to be measured in each frequency band of the frequency range of interest. Corrections for background n
39、oise shall be calculated in accordance with BS 4196 : Part 1. All quantities that allow determination of the operating point of the unit on test shall be measured and noted in accordance with BS 848 : Part 1. 5.4 Measurements and calculations Determination of the significance of discrete-frequency o
40、r narrow band components, qualification of the reverberation room, measurement of the sound pressure levels, and calculation of the sound power levels for all octave bands within the frequency range of interest, shall be carried out in accordance with BS 4196 : Part 1 and BS 4196 : Part 2. NOTE. Unc
41、ertainty in the determination of sound power levels is given in table 2. 6 Information to be reported The test report shall include at least the following: a) the date and location (name of the test facility) of the test; b) a description of the unit under test and the test standard used (e.g. BS 41
42、96 : Part 1); c) the location and mounting of the equipment under test, including a sketch of the test arrangement; d) the atmospheric conditions, e.g. temperature, barometric pressure, humidity; e) the operating conditions: air volume, static pressure, voltage, fan rotational speed; f) for non-duct
43、ed units: the sound power level per one-third octave and octave band for all operating points of the unit; g) for ducted units: the sound power level per one-third octave and octave band for all operating points of the unit, specifying, where appropriate: 1) the open inlet sound power level; 2) the
44、combined inlet and casing sound power (casing sound power) level; 3) the open outlet sound power level; 4) the length and cross section of the test ducts (see table 1); h) the overall A-weighted sound power level; i) an identification of discrete frequencies. NOTE. The sound power levels determined
45、for the inlet or outlet condition for a unit under test are not the usual in-duct levels for fans with a ducted inlet and/or outlet as specified in BS 848 : Part 2.4 BSI 1997 BS 4856 : Part 4 : 1997 1 m min. B B Section B-B Figure 1. Typical test installation for a wall-mounted unit BSI 1997 5 BS 48
46、56 : Part 4 : 1997 1 m min. 1 m min. 1 m 1 m min. Lagged duct D D Section D-D Figure 2. Typical test installation for a ducted unit6 BSI 1997 BS 4856 : Part 4 : 1997 1 m min. 1 m min. Lagged duct E E Section E-E Figure 3. Typical test installation for the open inlet and case radiated noise test BSI
47、1997 7 BS 4856 : Part 4 : 1997 1 m min. 1 m min. Lagged duct E E Section E-E Figure 4. Typical test installation for the case radiated noise testBS 4856 : Part 4 : 1997 8 BSI 1997 Annex Annex A (informative) Bibliography The following standards are recommended for further reading. BS 4856 : Methods
48、of testing and rating fan coil units, unit heaters and unit coolers BS 4856 : Part 1 : 1972 Thermal and volumetric performance for heating duties: without additional ducting BS 4856 : Part 2 : 1975 Thermal and volumetric performance for cooling duties: without additional ducting BS 4856 : Part 3 : 1
49、975 Thermal and volumetric performance for heating and cooling duties: with additional ductingBS 4856 : Part 4 : 1997 List of references (see clause 2) Normative references BSI publications BRITISH STANDARDS INSTITUTION, London BS 848 : Fans for general purposes BS 848 : Part 1 : 1997 Methods of testing performance BS 4196 : Sound power levels of noise sources BS 4196 : Part 1 : 1991 Precision methods for determinati
