1、 2008 Standard for Procedure for Estimating Occupied Space Sound Levels in the Application of Air Terminals and Air Outlets AHRI Standard 885 (formerly ARI Standard 885)Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproductio
2、n or networking permitted without license from IHS-,-,-Price $25.00 (M) $50.00 (NM) Copyright 2008 by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office IMPORTANT SAFETY DISCLAIMER AHRI does not set safety standards and does
3、not certify or guarantee the safety of any products, components or systems designed, tested, rated, installed or operated in accordance with this standard/guideline. It is strongly recommended that products be designed, constructed, assembled, installed and operated in accordance with nationally rec
4、ognized safety standards and code requirements appropriate for products covered by this standard/guideline. AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industry practices. AHRI does not certify or guarantee that any tests conducted under the sta
5、ndards/guidelines will not be non-hazardous or free from risk. FOREWORD This standard has been developed by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) for the purpose of establishing a uniform industry procedure for estimating Sound Pressure Levels in occupied spaces served by
6、 Air Terminals and/or air outlets. AHRI Standard 885 establishes uniform application practices for making Air Terminal sound path attenuation calculations. Such standards and procedures will be of mutual benefit to designers, engineers, consultants, building owners and other users for the purpose of
7、 providing building design information to meet acoustic goals. It should be recognized that the acoustical models and data used in AHRI Standard 885 are based on the best available data from both the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) and recognized in
8、dustry sources. Use of AHRI Standard 885 acoustical calculation procedures should provide a methodology for significantly improving the reliability of estimating the NC or RC levels in the occupied space over the more simplified acoustical models that have often been used in the past. The accuracy o
9、f all estimations depends on a significant body of experience accumulated with the use of this standard. AHRI Standard 885 has been in use for several years now, and has been proven to be a reliable method of sound estimation. Where the actual environment closely matches the assumptions, uncertainti
10、es of less than 5 dB in the estimated space sound level are commonly observed when these methods are employed. AHRI Standard 880 does not provide for determination of Sound Power in the 63 Hz octave band. These products do not contribute significantly to the sound levels in occupied spaces in the 63
11、 Hz octave band. The dominant source of sound levels in occupied spaces in the 63 Hz band is controlled by the primary air supply system. Since AHRI Standard 885 could be used to determine occupied space sound levels from the primary air supply system, data is provided where available in the 63 Hz o
12、ctave band. Note: This standard supersedes ARI Standard 885-98. 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-,-,-The Relationships of AHRI Standard 880 and 885 Alt
13、hough this standard does not take into account space sound level contributions from the central system fan, ductwork upstream of the Air Terminal, equipment room machinery or exterior ambient, these often significant sound sources should be considered in the designers work to achieve a complete esti
14、mate of room sound level. AHRI Standard 880 “Air Terminals” provides industry agreed-upon methods for determining sound power ratings of Air Terminal and air distribution devices. These sound power ratings are published in manufacturers data sheets. AHRI Standard 885 provides industry agreed-upon me
15、thods to use AHRI Standard 880 sound ratings to estimate the sound levels which will occur in the conditioned, occupied space. It provides calculation methods to examine and compare sound sources and attenuation in the application of Air Terminals and air distribution devices. Whats New This revisio
16、n to AHRI Standard 885 includes several updated tables and methods, reflecting research conducted and reported since the preparation of the 1998 version of the Standard. An electronic calculation spreadsheet has been added to accompany the Standard. The ISO end reflection table has been replaced wit
17、h one based on recent ASHRAE sponsored research. 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-,-,-TABLE OF CONTENTS PAGE Section 1. Purpose 1 Section 2. Scope .1 S
18、ection 3. Definitions .1 Section 4. Symbols .4 Section 5. Description of Sound Estimating Method .6 Section 6. Calculation Procedures for Estimating Sound Levels in Occupied Spaces 11 Section 7. Use of Noise Criteria (NC) and Room Criteria (RC) 24 Section 8. Other Design Considerations to Meet Acous
19、tic Goals 30 Section 9. Field Sound Diagnostics and Troubleshooting .33 Section 10. Conformance Conditions .36 TABLES Table 1. Octave Band Mid Frequencies 3 Table 2. Environmental Adjustment Factor 5 Table 3. Source Path Receiver Process .7 Table 4. Sound Sources and Paths in Acoustic Model 13 Table
20、 5. An Example from Typical Manufacturers Catalog 14 Table 6. Adjustment of Manufacturers Data 14 Table 7. Calculation Fan-Powered Terminal or Induction Terminal .15 Table 8. Step-By-Step Calculation for the Procedural Example of Figure 6 17 Table 9. Summary Combination of Path Results Using Logarit
21、hmic Addition .20 Table 10. Calculation Single/Dual Duct Terminal .23 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-,-,-TABLES (continued) Table 11. Calculation Int
22、egral Terminal 24 Table 12. Subjective Effect of Changes in Sound Pressure Level, Broadband Sounds 24 Table 13. Tabular Representation of NC Curves 30 Table 14. Tabular Representation of RC Curves .30 Table 15. Design Guidelines for HVAC System Noise in Unoccupied Spaces 31 Table 16. Example: Determ
23、ination of Maximum Allowable Sound Power .33 FIGURES Figure 1. Fan-Powered Terminal or Induction Terminal Acoustic Model .8 Figure 2. Single, Double Duct Terminal Acoustic Model 9 Figure 3. Integral Diffuser Terminal Acoustic Model 10 Figure 4. Decibel Addition Example 11 Figure 5. Fan-Powered Termi
24、nal or Induction Terminal Summary Calculation, Sound Sources and Paths 13 Figure 6. Fan-Powered Terminal or Induction Terminal Sample Calculation Acoustic Model 16 Figure 7. Single/Dual Duct Terminal Summary Calculation Sound Sources and Paths .21 Figure 8. Integral Terminal Summary Calculation Soun
25、d Sources and Paths .22 Figure 9. Example of Steps to Assign an RC Rating to a Noise Spectrum 27 Figure 10. NC Curves for Specifying the Design Level in Terms of the Maximum Permissible Sound Pressure Level for Each Frequency Band.28 Figure 11. RC Curves for Specifying the Design Level in Terms of a
26、 Balanced Spectrum Shape 29 Figure 12. Suggested Prediction Locations in Small Rooms 34 Figure 13. Suggested Small Room Microphone Locations if Low Frequency Standing Waves are Present 35 Copyright Air-Conditioning, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for R
27、esaleNo reproduction or networking permitted without license from IHS-,-,-APPENDICES Appendix A. References Normative 37 Appendix B. References Informative 37 Appendix C. Environmental Adjustment Factor Normative .38 Appendix D. Sound Path Factors Normative .39 Appendix E. Typical Sound Attenuation
28、Values Normative.58 TABLES FOR APPENDICES Table C1. Environmental Adjustment Factor 38 Table D1. Calculations for Attenuation Path Results .39 Table D2. Power Level Division at Branch Takeoffs 40 Table D3. TLoutversus Frequency for Various Circular Metal Ducts .42 Table D4. Breakout versus Frequency
29、 for 10 ft 3 m Sections of Non-Metallic Flexible Duct, Lined and Unlined .42 Table D5. TLoutversus Frequency for Flat-Oval Ducts .44 Table D6. TLoutversus Frequency for Rectangular Ducts .45 Table D7. Insertion Loss for Lined Circular Ducts 46 Table D8. Sound Insertion Loss/Attenuation in Straight L
30、ined Sheet Metal Ducts of Rectangular Cross-Section 47 Table D9. Lined Flexible Duct Insertion Loss .48 Table D10. Attenuation of Lined Round Elbows When Preceding and Following at Least 3 Lined Duct Diameters of Duct Lining 49 Table D11. Insertion Loss of Round Elbows .50 Table D12. Insertion Loss
31、of Unlined and Lined Elbows With/Without Turning Vanes 51 Table D13. End Reflection Loss 52 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-,-,-TABLES FOR APPENDICES
32、(continued) Table D14. Uncorrected Ceiling/Space Effect Attenuation Values .53 Table D15. Ceiling/Space Effect Examples .54 Table D16. Space Effect, Point Source 54 Table D17. Room Sound Attenuation for an Outlet Array, 4 Outlets 55 Table D18. Discharge Sound Effect Sample Calculations .56 Table D19
33、. Air Outlet Sound Estimates .57 Table E1. Typical Sound Attenuation Values 58 FIGURES FOR APPENDICES Figure D1. Branch Power Division 40 Figure D2. Circular Duct Breakout41 Figure D3. Flat Oval Duct Breakout 43 Figure D4. Rectangular Duct Breakout .44 Figure D5. Lined Circular Duct Insertion Loss .
34、45 Figure D6. Lined Flexible Duct Insertion Loss .49 Figure D7. Duct Elbow and Tee Loss 50 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-,-,-Copyright Air-Condition
35、ing, Heating and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-AHRI STANDARD 885-2008 (formerly ARI STANDARD 885-2008) 1 PROCEDURE FOR ESTIMATING OCCUPIED SPACE SOUND LEVELS IN THE APPLICATION OF AIR
36、TERMINALS AND AIR OUTLETS Section 1. Purpose 1.1 Purpose. The purpose of this standard is to provide a consistent industry-accepted method for estimating Sound Pressure Levels in a conditioned occupied space for the application of Air Terminals and air outlets. 1.1.1 Intent. This standard is intende
37、d 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. Scope 2.1 Scope. This standard includes sound levels from most but not all compon
38、ents in the air distribution system. Air Terminals, air outlets and the low pressure ductwork which connects them are considered as sound sources and are the subject of this Standard. This Standard does not make provisions to estimate space sound level contributions from the central system fan, duct
39、work upstream of the Air Terminal, equipment room machinery or exterior ambient sound. This Standard is not currently applicable for underfloor radiated or discharge sound calculations. AHRI Standard 880 does not provide for determination of sound power in the 63 Hz octave band. These products do no
40、t contribute significantly to the sound levels in occupied spaces in the 63 Hz octave band. The dominant source of sound levels in occupied spaces in the 63 Hz band is controlled by the primary air supply system. Since AHRI Standard 885 could be used to determine occupied space sound levels from the
41、 primary air supply system, data is provided where available in the 63 Hz octave band. The methods described in this Standard can be used to identify acoustically critical paths in the system design. The design effects of inserting alternative components and changes in the system can be evaluated. T
42、he accuracy of evaluating the difference in sound pressure between two alternatives is greater than individual estimations. Section 3. Definitions All terms in this document follow the standard industry definitions in the current edition of ASHRAE Terminology of Heating, Ventilation, Air Conditionin
43、g and Refrigeration unless otherwise defined in this section. 3.1 Air Terminal (Terminal). A device that modulates the volume of air delivered to a conditioned space in response to a given load. The various types of Air Terminals are defined as follows: 3.1.1 Bypass Terminal. Air Terminal that diver
44、ts excess primary air to the return. 3.1.2 Integral Diffuser Terminal. Diffuser with the features of an Air Terminal. 3.1.3 Dual Duct Terminal. Air Terminal with two supply inlets that is used primarily for mixing cold and warm air streams at varying proportions. Copyright Air-Conditioning, Heating
45、and Refrigeration Institute Provided by IHS under license with ARI Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-AHRI STANDARD 885-2008 (formerly ARI STANDARD 885-2008) 2 3.1.4 Induction Terminal. Air Terminal that supplies varying proportions of primary and indu
46、ced air. 3.1.5 Parallel Flow Fan-Powered Terminal. Air Terminal in which primary airflow is modulated in response to the cooling demand and in which the integral fan is operated to deliver induced air. 3.1.6 Reheat Terminal. Air Terminal that heats a single source of supply air. 3.1.7 Series Flow Fa
47、n-Powered Terminal. Air Terminal in which the primary airflow is modulated and mixed with induced air by a continuously operated integral fan to provide a relatively constant volume discharge. 3.1.8 Single Duct Terminal. Air Terminal supplied with one source of primary air. 3.2 Ceiling/Space Effect.
48、 Attenuation of Sound Power transmitted to an occupied space from above the ceiling as a result of the ceiling itself and the size of the space above the ceiling. 3.3 Duct Breakout. Sound associated with fan or airflow noise that radiates through the duct walls into the surrounding area. 3.4 Environ
49、mental Adjustment Factor. Difference between Sound Power Levels measured using a free field calibrated reference sound source and a reverberant field calibrated reference sound source. Sound Power measured in accordance with ASHRAE Standard 130 is based upon a free field calibrated reference sound so
