1、Price $10.00 (M) $20.00 (NM) Copyright 2014, by Air-Conditioning and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office 2014 Standard for Reverberation Room Qualification and Testing Procedures for Determining Sound Power of HVAC Equipment AHRI Standard 22
2、0 Price $10.00 (M) $20.00 (NM) Copyright 2014, 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 not certify or guarantee the safety of any products,
3、 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 recognized safety standards and code requirements appro
4、priate 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 its standards/guidelines will be non-hazardous or free from
5、 risk. Note: This standard supersedes ANSI/AHRI Standard 220-2012. This standard describes the methodology for determination of Sound Power Levels of broad-band, and/or discrete-frequency noise, and narrow-band noise sources in reverberation rooms. It is based on ANSI S12.51/ISO 3741. The method des
6、cribed herein requires reverberation room pre-qualification through test and the use of the Comparison Method to determine Sound Power Levels. This standard specifies the physical environment, procedures and equipment to qualify the reverberation room by test. Pre-qualifying the room ensures adequat
7、e modal density with the use of one source location to obtain acceptable accuracy and repeatability of results. The Reference Sound Source (RSS) used for the Comparison Method relies on ANSI/AHRI Standard 250 to accurately calibrate the RSS at all frequencies of interest. The use of the Comparison M
8、ethod reduces a number of potential sources of data collection and calculation errors. The standard contains information on instrumentation, installation and operation of the source, procedures for determining the number of microphone positions or length of traverse, and procedures for the calculati
9、on of Sound Power Levels. This standard is more restrictive than ANSI Standard S12.51/ISO 3741, which allows the user to test using either the Direct Method or the Comparison Method and also allows the user to employ a space with general characteristics. The intent of ANSI S12.51/ISO 3741 is to have
10、 a room that shall provide a “good” environment for testing, with the understanding that if the end result has a variation that is too high the user can increase the number of measurement locations to improve the spatial averaging and thus lower the variation. This is not practical for sources that
11、are difficult to move. TABLE OF CONTENTS SECTION PAGE Section 1. Purpose 1 Section 2. Scope . 1 Section 3. Definitions. 2 Section 4. Requirements for Qualification of Reverberation Rooms 3 Section 5. Reverberation Room Qualification Procedures 5 Section 6. Sound Power Testing Requirements and Calcul
12、ations . 8 Section 7. Information to BBe Recorded . 12 Section 8. Test Report 12 Section 9. Conformance Conditions 13 TABLES Table 1. Maximum Standard Deviations of Sound Power Level Reproducibility Determined in Accordance wtwith this Standard . 1 Table 2. Broadband Standard Deviation Limits 3 Tabl
13、e 3. Discrete Frequency Standard Deviation Limits 3 Table 4. Test Frequencies for Discrete Frequency Qualification . 7 Table 5. One-third Octave Band Frequency Range 8 Table 6. Background Correction Limits by One-third Octave Band 10 Table 7. One-third Octave Band Numbers and A-Weighting Factors 11
14、APPENDICES Appendix A. References Normative . 14 Appendix B. References Informative . 14 Appendix C. Sample Calculation Results Informative . 15 TABLES FOR APPENDICES Table C1. One-third Octaves . 15 Table C2. UUT Lw. 15 AHRI STANDARD 220-2014 1 REVERBERATION ROOM QUALIFICATION AND TESTING PROCEDURE
15、S FOR DETERMINING SOUND POWER OF HVAC EQUIPMENT Section 1. Purpose 1.1 Purpose. The purpose of this standard is to provide the methodology for the determination of Sound Power Levels of noise sources that emit Broadband Sound and/or Discrete Frequency Sounds/Tones in reverberation rooms. The method
16、described herein requires reverberation room pre-qualification through test and the use of the Comparison Method to determine Sound Power Levels. This standard specifies the physical environment, procedures, and equipment used to qualify the reverberation room by test. Pre-qualifying the room ensure
17、s adequate modal density with the use of one source locations to obtain acceptable accuracy and repeatability of results. The Reference Sound Source (RSS) used for the Comparison Method relies on ANSI/AHRI Standard 250 to accurately calibrate the RSS at all frequencies of interest. Sound rating valu
18、es are often useful for applications and design, therefore it is important to acquire data and qualify measurement rooms in One-third Octave Bands. The use of the Comparison Method reduces a number of potential sources of error. The standard contains information on instrumentation, installation and
19、operation of the source, procedures for determining the number of microphone positions or length of traverse, and procedures for the calculation of Sound Power Level. Measurements made in conformity with this standard will, with very few exceptions, result in standard deviations equal to or less tha
20、n specified in Table 1. The frequencies covered in this standard range from the 50 Hz to the 10,000 Hz One-third Octave Band (63 Hz to 8000 Hz Octave Bands). The 50 to 80 Hz one-third octave band sound for HVAC equipment affects product applications and often cannot be ignored. The product specific
21、AHRI standard will specify the frequency range of interest for qualification, calculation, and reporting. This standard is based on ANSI S12.51/ISO 3741 but provides additional exceptions and extensions. Table 1. Maximum Standard Deviations of Sound Power Level Reproducibility Determined in Accordan
22、ce with this Standard One-third Octave Band Center Frequency, Hz One-third Octave Band Maximum Standard Deviation of Reproducibility, R0, dB 50 - 80 4.0 100 - 160 3.0 200 - 315 2.0 400 - 5000 1.5 6000 - 10000 3.0 1.1.1 Intent. This standard is intended for the guidance of the industry, including man
23、ufacturers, 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 applies to HVAC products where sound power is determined by measurement using the Comparison Method
24、 in a reverberation room that meets the qualification requirements as defined in Section 4 of this standard. AHRI STANDARD 220-2014 _ 2 Section 3. Definitions All terms in this document will follow the standard industry definitions in the ASHRAE Terminology website (https:/www.ashrae.org/resources-p
25、ublications/free-resources/ashrae-terminology) unless otherwise defined in this section. 3.1 Broadband Sound. Sound that is random in nature with frequency components distributed over a broad frequency band. Typically pure tones or periodic disturbances will not be distinguishable in this type of so
26、und spectrum. 3.2 Comparison Method. A method of determining Sound Power Level by comparing the average Sound Pressure Level produced in the room to a Reference Sound Source of known sound power level output. The difference in Sound Power Level is equal to the difference in Sound Pressure Level when
27、 conditions in the room are the same for both sets of measurements. 3.3 Direct Method. A method of determining sound power level from the measured sound pressure levels produced by the source under test in a reverberation room and from the reverberation time and volume of the reverberation room. 3.4
28、 Discrete Frequency Sounds/Tones. These consist of one or more sound waves, each of which is essentially sinusoidal. 3.5 Discrete Frequency Source. A noise source that produces Discrete Frequency Sounds/Tones. 3.6 Low Frequency Data. Data in the 63 Hz Octave Band (50, 63, and 80 Hz One-third Octave
29、Bands). 3.7 Octave Band. A band of sound covering a range of frequencies such that the highest is twice the lowest. The Octave Bands used in this standard are those defined in ANSI Standard S1.11. 3.8 One-third Octave Band. A band of sound covering a range of frequencies such that the highest freque
30、ncy is the cube root of two times the lowest frequency. The One-third Octave Bands used in this standard are those defined in ANSI Standard S1.11. 3.9 Reference Sound Source (RSS). A portable, aerodynamic sound source that produces a known stable broadband sound power output. 3.10 “Shall“ or “Should
31、.“ “Shall“ or “should“ 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 compliance with the standard is claimed. 3.10.2 Should. “Should“ is used to indicate provisions which are not mandatory but which are d
32、esirable as good practice. 3.11 Sound Power Level, Lw. Ten times the logarithm to the base ten of the ratio of the sound power radiated by the source to a reference sound power, expressed in decibels, dB. The reference sound power used in this standard is 1 picowatt, pW. 3.11.1 A-weighted Sound Powe
33、r Level (LwA). The logarithmic summation of A-weighted, one-third octave band Sound Power Levels. 3.12 Sound Pressure Level, Lp. Twenty times the logarithm to the base ten of the ratio of a given sound pressure to a reference sound pressure of 20 Pa, expressed in decibels, dB. 3.13 Unit Under Test (
34、UUT). HVAC equipment or duct termination for which the sound power is to be determined. AHRI STANDARD 220-2014 3 Section 4. Requirements for Qualification of Reverberation Rooms 4.1 Reverberation Room Requirements. The acoustic and physical environment of the reverberation room shall be qualified by
35、 test to meet the requirements of ANSI Standard S12.51/ISO 3741 Sections 5.1, 5.5, Annex A, Annex E, and Annex D except as noted in Sections 4.3 and 4.4 and the room volume requirements below. The minimum room volume for qualification of frequencies below the 100 Hz One-third Octave Band shall be 28
36、0 m3. If only One-third Octave Bands equal to and above 100 Hz are required, the minimum room volume shall be 200 m3. 4.2 Instrumentation Requirements. Instrumentation shall meet or exceed the requirements of Class 1 as specified in ANSI Standard S1.4. over the frequency range of interest. The micro
37、phone(s) used for all measurements shall be of the diffuse field/random incident type. 4.3 Standard Deviation Requirements for Broadband Room Qualification. The requirements of this standard for broadband room qualification are defined in Table 2. Table 2. Broadband Standard Deviation Limits Octave
38、Band Center Frequency, Hz One-third Octave Band Center Frequency, Hz Standard Deviation Ss, dB 63 125 250 500 1000 2000 4000 8000 50, 63, 80 100, 125, 160 200, 250, 315 400, 500, 630 800, 1000, 1250 1600, 2000, 2500 3150, 4000, 5000 6300, 8000, 10000 2.0 1.5 1.0 1.0 0.5 0.5 1.0 1.0 4.3.1 Broadband S
39、ource. For the purposes of this standard, the RSS used to qualify the reverberation room for broadband measurements shall meet the requirements of ANSI/AHRI Standard 250. 4.4 Standard Deviation Requirements for Discrete Frequency Room Qualification. The requirements of this standard for discrete-fre
40、quency room qualification are defined in Table 3. Table 3. Discrete Frequency Standard Deviation Limits Octave Band Center Frequency, Hz One-third Octave Band Center Frequency, Hz Standard Deviation Ss, dB 63 125 250 500 1000 2000 50, 63, 80 100, 125, 160 200, 250, 315 400, 500, 630 800, 1000, 1250
41、1600, 2000, 2500 4.0 3.0 2.0 1.5 1.0 1.0 AHRI STANDARD 220-2014 _ 4 4.4.1 Discrete Frequency Source. For the purposes of this standard, the Discrete Frequency Source used to qualify the reverberation room shall meet the requirements of Section 5.2.2. 4.5 Microphone Locations. No microphone position
42、or point on a traverse shall be less than 1.5 m from any of the reverberation rooms surfaces. At no point shall the microphone be any closer than 0.5 m to any surface on a rotating diffuser. The minimum distance between the microphone and each measurement location shall be determined using Equation
43、1. = 2 10207T 1 Where: dmin = Minimum distance between the microphone and source, m D2 = 0.4 for One-third Octave Bands from 50to 80 Hz and from 6300 Hz to 10,000 Hz = 0.8 for One-third Octave Bands from 100to 5000 Hz Lpr= The Sound Pressure Level of the RSS in any One-third Octave Band measured in
44、the reverberation room Lwr = The calibrated Sound Power Level of the RSS in any One-third Octave Band The dminshall be computed for each One-third Octave Band and each potential source location for which the room is to be qualified. The maximum calculated dminvalue shall be the minimum distance betw
45、een the microphone and the source for room qualification and for unit testing. 4.6 Microphone Traverse. If a traversing microphone is used, the space averaging of the sound data shall be measured using a microphone traversing at a constant speed over a path length greater than or equal to 3 for One-
46、third Octave Bands of 100 Hz and above and 3/2 for the 50 Hz through 80 Hz One-third Octave Bands. The same microphone traverse shall be used for both room qualification and sound power determination. = c/f 2 = 20.05 (273 + )7T 3 Where: c = The speed of sound of the air, m/sf = The center frequency
47、of the lowest band of interest, Hz = The temperature of the air in the reverberation test room at the time of test, C 4.6.1 Path of Microphone Travel. The path may be a line, semicircle, circle, or other geometric shape. 4.6.2 Microphone Traverse Speed. The speed of the traversing microphone shall b
48、e constant and shall not exceed 1 meter per second. There shall be a whole number of microphone traverses completed during the analyzers measurement time interval, no partial traverses are allowed. 4.6.3 Microphone Traverse Location. The microphone traverse shall be within the reverberant field. Note: It is good practice for the microphone traverse to not lie in a plane parallel to any room surface, including walls, the floor or the ceiling. 4.7 Fixed Microphones. If an array of microphones is used, it shall consist of at least six fixed microphones (or microphone positions) spaced
