1、2008 Standard forPerformance andCalibration of ReferenceSound SourcesARI Standard 250Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Price $10.00 (M) $20.00 (NM)
2、Copyright 2008, by Air-Conditioning, Heating, and Refrigeration InstitutePrinted in U.S.A. Registered United States Patent and Trademark OfficeIMPORTANTSAFETY DISCLAIMERAHRI does not set safety standards and does not certify or guarantee the safety of any products, components orsystems designed, tes
3、ted, rated, installed or operated in accordance with this standard/guideline. It is stronglyrecommended that products be designed, constructed, assembled, installed and operated in accordance withnationally recognized safety standards and code requirements appropriate for products covered by thissta
4、ndard/guideline.AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industrypractices. AHRI does not certify or guarantee that any tests conducted under its standards/guidelines will be non-hazardous or free from risk.This standard supersedes ARI Standa
5、rd 250-2001.This standard differs from the 2001 version in that it references ARI Standard 220 in place ofANSI Standards S12.31 and S12.32, both of which have been withdrawn. Additionally thisstandard now references ANSI Standard S12.55 in place of ANSI Standard S12.35 which hasalso been withdrawn.C
6、opyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-TABLE OF CONTENTSSECTION PAGESection 1. Purpose .1Section 2. Scope 1Section 3. Definitions 1Section 4. Performance
7、Requirements.2Section 5. Primary RSS Calibration Procedure .3Section 6. Secondary RSS Transfer Calibration Procedure.5Section 7. Test Requirements 6Section 8. Test Data To Be Recorded6Section 9. Information To Be Recorded6Section 10. Minimum Data Requirements for Published Information7Section 11. Re
8、calibration.7Section 12. Conformance Conditions8TABLESTable 1. RSS Sound Power Level Output Standard Deviations.3Table 2. Minimum Reverberant Room Volume for Secondary RSSTransfer Calibration5Table 3. RSS Tolerance Levels 7FIGURESFigure 1. Microphone Path 4Copyright Air-Conditioning, Heating and Ref
9、rigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-APPENDICESAppendix A. References Normative .9Appendix B. References Informative9Appendix C. Example for the Determination of the Presence of a Tone Informati
10、ve10Appendix D. Alternative Primary RSS Calibration Procedure Normative.11Appendix E. Procedures for Determining Windscreen Corrections Normative.12Appendix F. Example for the Determination of the Directivity Index and Resultant RSSCalibration Informative .13TABLES FOR APPENDICESTable C1. Example fo
11、r the Determination of the Presence of a Tone.10Table D1. Tolerance for Sound Power Level Difference 11Table F1. Example for the Determination of the Directivity Index and Resultant RSSCalibration 13Table F2. RSS Maximum Sound Pressure Levels in One-third Octave Bands, Lpi14Table F3. RSS One-third O
12、ctave Bands Directivity Index, dB 15Table F4 Resultant RSS Calibration16Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ARI STANDARD 250-20081PERFORMANCE AND CALI
13、BRATION OF REFERENCESOUND SOURCESSection 1. Purpose1.1 Purpose. The purpose of this standard is to establish the performance characteristics of a Reference Sound Source, definethe acoustical calibration procedures, and define the method for transfer of calibration from a Primary to a Secondary or Wo
14、rkingReference Sound Source.1.1.1 Intent. This standard is intended for the guidance of the industry, including manufacturers, engineers, installers,contractors and users.1.1.2 Review and Amendment. This standard is subject to review and amendment as technology advances.Section 2. Scope2.1 Scope. Th
15、is standard applies to all Reference Sound Sources used in conjunction with ARI sound rating standards andcovers the one-third octave band frequency range from 50 to 10,000 Hz. This standard also includes calibration over a limitedfrequency range. Multiple Reference Sound Sources may be used to cove
16、r the entire frequency range from 50 to 10,000 Hz.Section 3. DefinitionsAll terms in this document shall follow the standard industry definitions in the current edition of ASHRAE Terminology of Heating,Ventilation, Air Conditioning and Refrigeration unless otherwise defined in this section.3.1 Direc
17、tivity Index(Di). An indicator, expressed in decibels (dB), of the non-uniform spatial sound radiation of the ReferenceSound Source being calibrated.3.2 Hertz (Hz). A unit of frequency equal to one cycle per second.3.3 Octave Band. A band of sound covering a range of frequencies such that the highes
18、t is twice the lowest. The Octave Bandsused in this standard are those defined in ANSI Standard S1.11.3.4 One-Third Octave Band. A band of sound covering a range of frequencies such that the highest frequency is the cube rootof two times the lowest frequency. The One-Third Octave Bands used in this
19、standard are those defined in ANSI Standard S1.11.3.5 One-Twelfth Octave Band. A band of sound covering a range of frequencies such that the highest frequency is the twelfthroot of two times the lowest.3.6 Reference Sound Source (RSS). A portable, aerodynamic sound source that produces a known stabl
20、e broad band soundpower output. The device shall meet the performance requirements as defined in Section 4.3.6.1 Primary Reference Sound Source. A laboratory standard RSS whose Sound Power Levels are determined by usingthe procedures as defined in Section 5. It may also be used as a Working RSS as d
21、efined in 3.6.3.3.6.2 Secondary Reference Sound Source. A laboratory Working RSS whose Sound Power Levels are determined byusing the transfer calibration procedure as defined in Section 6.3.6.3 Working Reference Sound Source. An RSS that is used for day to day sound room testing. The device shall be
22、calibrated as a Primary RSS or a Secondary RSS.Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ARI STANDARD 250-200823.7 Sound Intensity Level, Li. Ten times the
23、logarithm to the base ten of the ratio of the magnitude of the intensity to thereference intensity of 1 picowatt per square meter (pW/m2).3.8 Sound Power Level, Lw. Ten times the logarithm to the base ten of the ratio of the sound power radiated by the source to areference sound power, expressed in
24、decibels (dB). The reference sound power used in this standard is 1 picowatt (pW).3.9 Sound Pressure Level, Lp. Twenty times the logarithm to the base ten of the ratio of a given sound pressure to a referencesound pressure of 20 Pa, expressed in decibels (dB).3.10 “Shall” or “Should”. “Shall” or “sh
25、ould” shall be interpreted as follows:3.10.1 Shall. Where “shall” or “shall not” is used for a provision specified, that provision is mandatory if compliancewith the standard is claimed.3.10.2 Should. “Should” is used to indicate provisions which are not mandatory but which are desirable as good pra
26、ctice.3.11 Tone. Any measured one-twelfth octave band Sound Pressure Level that is less than 5 dB below the corresponding octaveband Sound Pressure Level (4.1).Section 4. Performance Requirements4.1 Type of Sound Source. A portable, aerodynamic sound source that produces a known stable broad band so
27、und power outputwith no tones within the frequency range of interest shall be used. The presence of a tone is defined by the following equation:Lp Lp1/12th i 5 1where:Lp = Octave Band Sound Pressure LevelLp1/12th i = Sound Pressure Level for the ith One-Twelfth Octave BandRefer to Appendix C for an
28、example.4.2 Reference Sound Source Spectral Characteristics. The spectrum of the Reference Sound Source shall be broad band andthe spread of one-third octave band Sound Power Levels of the RSS when calibrated over the frequency range of 50 10,000 Hzshall not exceed 16 dB. When the Reference Sound So
29、urce is only calibrated over the frequency range of 100 to 10,000 Hz thespread of one-third octave band Sound Power Levels of the RSS shall not exceed 12 dB. Regardless of the frequency range ofcalibration adjacent bands shall not deviate by more than 3 dB when tested in accordance with this standar
30、d.4.3 Reference Sound Source Size. The largest dimension of the source shall not exceed 0.5 m.4.4 Vibration Isolation. The RSS shall be equipped with integral vibration isolation so that it will provide a minimum of 95%isolation at its rotational speed.4.5 Temporal Steadiness and Repeatability of th
31、e Sound Power Output. The Reference Sound Source shall be designed andconstructed so that the Sound Power Level, under repeatable conditions, in each One-Third Octave Band is constant in time asgiven in Table 1.Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under lic
32、ense with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ARI STANDARD 250-20083Table 1. RSS Sound Power Level OutputStandard DeviationsFrequency Range, Hz Sound Power LevelOutput StandardDeviation, dB50 - 80 0.8100 - 160 0.4200 10,000 0.24.5.1 Sound Power Leve
33、l Variation from Electrical Variation. The RSS Sound Power Level in any One-Third OctaveBand shall not vary by more than 0.3 dB within the range of the source electrical power. The manufacturer shall providethe tolerances of electrical input power to assure only a 0.3 dB deviation.4.5.2 Sound Power
34、Level Variation from Atmospheric Conditions. The Sound Power Level of the Reference SoundSource may depend on the atmospheric pressure and temperatures along with the altitude. The manufacturer shall provideappropriate correction values for these variables.4.6 Directivity Index. The Directivity Inde
35、x of the Reference Sound Source in any One-Third Octave Band from 50 to 10,000Hz at any microphone height shall not exceed + 6 dB.Section 5. Primary RSS Calibration Procedure5.1 General. The RSS calibration procedure shall be carried out in accordance with the provisions of Section 5 or as providedi
36、n Appendix D.5.2 Test Environment. The test environment shall be a hemianechoic space meeting or exceeding the qualification requirementsof ANSI Standard S12.55. The hard surface shall extend at least 1 m beyond the projection of the measurement surface in alldirections. In addition, the volume of t
37、he test room shall be greater than 280 m3.5.3 Microphone. A calibrated 12 mm free field microphone mounted with its axis 0o towards the Reference Sound Source shallbe used. The microphone frequency response shall be corrected to give a flat frequency response within 0.1 dB over the frequencyrange of
38、 interest.5.4 Microphone Positions. The measurement surface shall be a hemisphere with a radius of 2 m. The center of this hemisphereshall be located on the floor directly below the center of the RSS fan wheel.5.5 Microphone Path. The path to be used is defined as twenty coaxial, horizontal circular
39、 traverses on the surface of the2 m radius hemisphere and around a vertical axis passing through the center of the RSS fan wheel. The traverse speed shallnot exceed 1 rpm. The twenty coaxial, horizontal circular traverses shall start at a height of 0.025r (r = radius) starting fromthe floor and incr
40、ease in 0.05r increments to 0.975r (Figure 1).Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ARI STANDARD 250-20084Figure 1. Microphone PathThe circular path may
41、 be achieved by uniformly rotating either the microphone or RSS through 360. If the RSS is to be rotated,the top surface of the turntable shall be flush with the floor (rotational speed not to exceed 1 rpm).5.6 Measurements. Measure the one-third octave band Sound Pressure Level in accordance with A
42、NSI Standard S12.55 withan integration time equal to one complete revolution of the microphones or source. The analyzer shall be capable of makingmeasurements to 0.1 dB.5.7 Calculations. The one-third octave band Sound Power Levels shall be computed per ANSI Standard S12.55 using thesurface Sound Pr
43、essure Levels calculated in accordance with ANSI Standard S12.55 and they shall be rounded to the nearest 0.1decibels.5.8 Directivity Index Calculation. The maximum measured Sound Pressure Level or maximum measured Sound Intensity Levelfor each One-Third Octave Band at each microphone height shall b
44、e used to compute the Directivity Index. The Directivity Indexshall not be computed for the 0.025r microphone height. The maximum calculated Directivity Index for each One-Third OctaveBand shall be published per section 10.2 item l.Di = Lpi or Lii Lp 2Where:Di = Directivity Index for a given One-Thi
45、rd Octave BandLpi = Maximum measured Sound Pressure Level for a given One-Third Octave Band at a given microphoneheightorLii = Maximum measured Sound Intensity Level for a given One-Third Octave Band at a given microphoneheightLp = Average Sound Pressure Level for a given One-Third Octave Band over
46、the surface of the measurementhemisphereRefer to Appendix F for an example.Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ARI STANDARD 250-200855.9 Instrumentati
47、on and Equipment. The instrumentation and equipment shall meet or exceed the requirements of ANSIStandard S12.55.5.10 Use of Windscreens. A windscreen shall be used for all testing and it shall not affect the microphone response by more than 1 dB from 50 to 4,000 Hz or 1.5 dB for frequencies above 4
48、,000 Hz. When using a sound intensity probe, the windscreeneffect shall be allowed to vary an additional 0.5 dB to those stated above. Windscreen corrections shall be determined perAppendix E of this standard. These corrections shall be added to the measurements made in 5.6 or Appendix D of this sta
49、ndard.5.11 Calibration Over a Limited Range. This standard allows the RSS to be calibrated over a limited range of frequencies. Ifthe RSS is calibrated over a limited range then the range of calibration shall be reported.Section 6. Secondary RSS Transfer Calibration Procedure6.1 Test Environment. The test environment shall be a reverb
