AHRI 230-2013 Sound Intensity Testing Procedures for Determining Sound Power of HVAC Equipment.pdf

1、 2013 Standard for Sound Intensity Testing Procedures for Determining Sound Power of HVAC Equipment AHRI Standard 230 Price $10.00 (M) $20.00 (NM) Copyright 2013, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office IMPORTAN

2、T SAFETY DISCLAIMER AHRI does not set safety standards and does 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, ass

3、embled, installed and operated in accordance with nationally recognized 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

4、 not certify or guarantee that any tests conducted under its standards/guidelines will be non-hazardous or free from risk. Note: This is a new Standard. This standard describes the methodology for determination of Sound Power Levels of broad-band, and/or discrete-frequency noise sources using the in

5、tensity method. It is based on sound tests utilizing the sound intensity method as described in ISO 9614-1 (measurement at discrete points, grade 2) or ISO 9614-2 (measurement by scanning, grade 2). TABLE OF CONTENTS SECTION PAGE Section 1. Purpose 1 Section 2. Scope . 1 Section 3. Definitions. 1 Se

6、ction 4. General Requirements . 2 Section 5. Acoustic Environment 3 Section 6. Instrumentation . 3 Section 7. Measurement of Component Sound Intensity Levels . 4 Section 8. Information to be Recorded 8 Section 9. Test Report 9 Section 10. Conformance Conditions 9 TABLES Table 1. Maximum Standard Dev

7、iations of Sound Power Level Reproducibility Determined in Accordance With This Standard . 1 Table 2. Performance Verification Limits 4 Table 3. Convergence Index . 5 Table 4. One-third Octave Band Numbers and A-Weighting Factors 8 FIGURES Figure 1. Performance Verification Measurement Grid . 4 APPE

8、NDICES Appendix A. References Normative . 10 Appendix B. References Informative . 10 AHRI STANDARD 230-2013 _ 1 SOUND INTENSITY TESTING PROCEDURES 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 determin

9、ation of Sound Power Levels of noise sources using the sound intensity method. The standard contains information on instrumentation, installation and operation of the source and procedures for the calculation of Sound Power Level. This standard covers the frequency range from the 50 Hz to the 10,000

10、 Hz One-third Octave Band (63 Hz to 8000 Hz Octave Bands). The product specific AHRI sound performance rating standard will specify the frequency range of interest for qualification, calculation, and reporting. This standard is based on ISO 9614-1 (grade 2) or ISO 9614-2 (grade 2) but provides addit

11、ional exceptions and extensions. Section 7.2 refers to measurement at discrete points and Section 7.3 refers to measurement by scanning. 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 A

12、mendment. This standard is subject to review and amendment as technology advances. 1.2 Measurement Uncertainty. Sound Power Levels obtained from intensity measurements made in conformance with this standard shall result in measurement standard deviations which are equal to or less than those in Tabl

13、e 1. The uncertainties in this table include uncertainty in the sound intensity measurement method due to the test environment, background noise levels and selection of measurement points as defined in ISO 9614-1 (grade 2) or measurement surfaces in ISO 9614-2 (grade 2). The standard deviations in T

14、able 1 do not account for variations of sound power caused by changes in operating conditions. Table 1. Maximum Standard Deviations of Sound Power Level Reproducibility Determined in Accordance With This Standard One-third Octave Band Center Frequency, Hz One-third Octave Band Maximum Standard Devia

15、tion of Reproducibility, dB 50 - 80 4.0 100 - 160 3.0 200 - 315 2.0 400 - 5000 1.5 6000 - 10000 3.0 Section 2. Scope 2.1 Scope. This standard applies to HVAC products where sound power is determined by measurement using the sound intensity method. This standard provides a standalone method of test t

16、hat is referenced by other AHRI sound performance rating standards and provides an alternative to the reverberation room method of test outlined in AHRI Standard 220. Section 3. Definitions All terms in this document will follow the standard industry definitions in the ASHRAE Wikipedia website (http

17、:/wiki.ashrae.org/index.php/ASHRAEwiki) 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 sound spe

18、ctrum. 3.2 Discrete Frequency Sounds/Tones. These consist of one or more sounds, each of which is essentially sinusoidal. 3.3 Discrete Frequency Source. A noise source that produces Discrete Frequency Sounds/Tones. _ AHRI STANDARD 230-2013 2 3.4 Octave Band. A band of sound covering a range of frequ

19、encies such that the highest is twice the lowest. The Octave Bands used in this standard are those defined in ANSI Standard S1.6. 3.5 One-third Octave Band, n. A band of sound covering a range of frequencies such that the highest frequency is the cube root of two times the lowest frequency. The One-

20、third Octave Bands used in this standard are those defined in ANSI Standard S1.6. 3.6 Pressure-Residual Intensity Index (PRI). The difference between the indicated Sound Pressure Level, Lp, and the indicated Sound Intensity Level, Li, when the intensity probe is placed in a sound field such that Lii

21、s zero for each frequency band. Details of determining the PRI are provided in Clause 6.1 of ISO 9614-1 and ISO 9614-2. 3.7 Reference Sound Source (RSS). A portable, aerodynamic sound source that produces a known stable broadband sound power output. 3.8 “Shall“ or “Should.“ “Shall“ or “should“ shall

22、 be interpreted as follows: 3.8.1 Shall. Where “shall“ or “shall not“ is used for a provision specified, that provision is mandatory if compliance with the standard is claimed. 3.8.2 Should. “Should“ is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.9

23、 Reproducibility. Deviations in test results obtained with the same method on identical test items in different laboratories with different operators using different test instrumentation. 3.10 Sound Intensity Level, Li. Ten times the logarithm to the base ten of the ratio of the sound intensity comp

24、onent radiated by the source to a reference sound intensity, expressed in decibels (dB). The reference sound intensity used in this standard is 1 picowatt per meter squared (pW/m2). The sound intensity component is the value of the intensity vector, normal to a measurement surface, directed out of a

25、 volume enclosing the sound source. 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 S

26、ound Power 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 Und

27、er Test (UUT). HVAC equipment or duct termination for which the sound power is to be determined. Section 4. General Requirements 4.1 Size of Noise Source. The size and shape of the noise source is unrestricted and serves to define the measurement surface. The measurement surface, consisting of multi

28、ple sub-surfaces, shall totally enclose the noise source under test. The basic concept is measurement of the sound intensity distribution around the equipment. 4.2 Character of Noise Radiated by the Source. The signal shall be stationary in time, as defined in Clause 3.13 of ISO 9614-1 (grade 2) and

29、 Clause 3.13 of ISO 9614-2 (grade 2). Care should be taken to avoid measurement during times of operation of non-stationary extraneous noise sources of which the occurrences are predictable. 4.3 Time Averaging. To minimize the random error in the measurement, it is required that the averaging time b

30、e long enough to give repeatable results. The minimum averaging time shall be 30 seconds per each square meter of measurement surface. AHRI STANDARD 230-2013 _ 3 Section 5. Acoustic Environment 5.1 Criteria for Adequacy of the Test Environment. The temperature, humidity and barometric pressure of th

31、e test environment shall be within the instrument manufacturers stated limits. In addition, the test environment shall satisfy the requirements stated in clauses 5.2 to 5.4 of ISO 9614-1 (grade 2) and 5.2 to 5.4 of ISO 9614-2 (grade 2) covering extraneous intensity, vibration, temperature, configura

32、tion of the surroundings and atmospheric conditions. Even though sound intensity measurements are relatively insensitive to background sound compared to other methods, an excessive amount of background sound will increase the uncertainty of the measurements. The background Sound Pressure Level shall

33、 be no greater than the direct sound from the equipment under test. Care shall be taken to ensure that flowinduced noise over the intensity probe does not influence the measurements. Measurements shall be performed with a windscreen at all times. The windscreen shall meet the requirements of AHRI St

34、andard 250 Section 5.10. Averaging times may be extended to improve the measurement results. Intensity measurements in airflow shall meet the requirements in Section 6.3. For some measurements consisting of discrete points according to ISO 9614-1 or scanned sub-surfaces according to ISO 9614-2, it m

35、ay not be possible to eliminate flow-induced noise over the intensity probe. Provided all measurements that are invalid due to flow-induced noise do not exceed 10% of the total measurement surface area, such discrete points or scanned sub-surfaces may be excluded when determining the sound power of

36、the noise source. Section 6. Instrumentation 6.1 General. The sound intensity instruments and probes used for measurement shall meet the class 1 requirements of IEC 61043. Measurements and analysis shall be conducted in One-third Octave Bands using equipment in compliance with ANSI Standard S1.11. S

37、ynthesized One-third Octave Band levels from narrow band analysis are not allowed. For the calibration and field check of the instruments, see the requirements of Clause 6.2 of ISO 9614-1 (grade 2) and 9614-2 (grade 2). The two values of the normal sound intensity, I(n), at each One-third Octave Ban

38、d for the field check should have opposite signs and the allowable difference in Sound Intensity Levels, Li, shall be less than 1.5 dB in all bands. 6.2 Instrumentation. The sound intensity instrumentation shall be capable of measurements from the 50 Hz to the 10,000 Hz One-third Octave Band. A comm

39、on sound intensity probe consists of two 12mm diameter pressure microphones in a face-to-face configuration with a solid spacer between the microphone grids. The use of two different intensity microphone spacers may be required to cover the entire frequency range in conformance with Table 1. A 50mm

40、microphone spacer is typically used for the one-third octave band frequency range from 50 Hertz to 315 Hertz; a 12mm microphone spacer is typically used for the one-third octave band frequency range from 400 Hz to 10,000 Hz. The use of a single microphone spacer for the entire range of frequency ban

41、ds is, however, permitted if the requirements of Sections 6.3 and 6.4 are met. Some intensity analyzers have a built in feature to correct for the high frequency roll off of the intensity probe with a specific microphone spacer. If the analyzer does not provide a high frequency correction, the proce

42、dure in Section 6.4 may also be used to quantify the high frequency correction at the 1,600 Hz through 10,000 Hz One-third Octave Bands. The Pressure-Residual Intensity Index (PRI) of the measurement instrumentation (microphone pair, spacer and analyzer) shall be recorded according to the procedure

43、in Clause 6.1 of ISO 9614-1 and ISO 9614-2 for each frequency band. This procedure is referred to as phase calibration. The procedure in Section 6.3 of this standard is then used to check the quality of each sound intensity measurement. 6.3 Qualification of Sound Intensity Measurements. To conform w

44、ith this standard, the quality of each measurement shall meet the following requirements for each One-third Octave Band: PI(n) PRI(n) 10 1 Where: PI(n)= Pressure-intensity index (mean-pressure level minus the intensity level) of the measurement for the nthOne-third Octave Band, dB _ AHRI STANDARD 23

45、0-2013 4 PRI(n)= Pressure-Residual Intensity Index, determined by the phase calibration of the particular microphone pair, spacer and analyzer used for the measurement for the nthOne-third Octave Band, dB Measurements in each frequency band that do not meet this requirement are invalid. Measurements

46、 in each frequency band where the mean-pressure level is less than the intensity level (PI index is negative) are also invalid. This condition often occurs when the measurement is influenced by flow-induced noise over the probe. 6.4 High Frequency Correction. For measurements systems using 10 to 15

47、mm microphone spacers, the results of the performance verification in Section 6.5 may be used to determine a high frequency correction for each individual sound intensity probe and analyzer combination. The probe correction, Lwi(n), is the one-third octave band level in decibels that is added to the

48、 sound power, determined by the intensity measurements, to equal the sound power of the Reference Sound Source (RSS). The high-frequency probe correction shall only be applied to the 1600 Hz through 10,000 Hz One-third Octave Bands. 6.5 Performance Verification by Comparison with a Reference Sound Source. In order to ensure consistent and accurate sound intensity results, it is required to periodically verify the performance of the instrumentatio