AHRI 575-2008 Method of Measuring Machinery Sound Within an Equipment Space.pdf

1、 Price $15.00 (M) $30.00 (NM) 8Copyright 1994, by Air-Conditioning and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office 2008 Standard for Method of Measuring Machinery Sound Within an Equipment Space ANSI/AHRI Standard 575 (Formerly ARI Standard 575) Pri

2、ce $10.00 (M) $20.00 (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 not certify or guarantee the safety of any products, comp

3、onents 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 appropriat

4、e 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 risk

5、. FOREWORD This document establishes a uniform method of measuring the sound levels produced by air-conditioning and refrigerating machinery installed in mechanical equipment spaces. However, it should be emphasized that this standard was developed for use where the test conditions usually cannot be

6、 controlled, e.g., ambient temperature; equipment loading; physical attributes of the space; background sound sources, etc. Since the results obtained may vary substantially, a tolerance on these results cannot be specified. Uniform practices in making sound level measurements are necessary for effe

7、ctive communication between the owner, the architect, the acoustician, the consulting engineer, the contractor and the equipment manufacturer. Specifications for sound levels produced by machinery may be written, both for the purpose of supplying information in order to evaluate compliance with nois

8、e exposure limits and for the purpose of providing information for adequate building design to meet the acoustical design goals of adjacent occupied spaces. In view of the geometrical and acoustical properties of large equipment, both purposes can best be served by sound data expressed in terms of S

9、ound Pressure Level measured close to the equipment. Sound pressure measurements close to the equipment are least affected by the environment in which the machines are installed. This standard is based upon the procedures established in ANSI Standard S1.13. Note: This standard supersedes ARI Standar

10、d 575-94 and has no technical changes. TABLE OF CONTENTS PAGE Section 1. Purpose . 1 Section 2. Scope 1 Section 3. Definitions 1 Section 4. Instruments . 2 Section 5. Sound Measurements and Calculation Procedures . 2 Section 6. Machinery Sound Specifications and Data Presentation 4 Section 7. System

11、 Operating Conditions . 5 Section 8. Conformance Conditions 5 FIGURES Figure 1. Test Unit Measurement Points . 3 Figure E1. Example Sketch Showing Microphone Locations, Orientation of Test Unit, Key Measurement Points and Surroundings 14 APPENDICES Appendix A. Reference Normative . 6 Appendix B. Ref

12、erence Informative . 6 Appendix C. Operating Conditions Informative . 7 Appendix D. Sound Level Recording Format Per ARI Standard 575 Informative 11 Appendix E. Example of Sound Level Recording Format Per ARI Standard 575 Informative.12 FORMS Form C1. Centrifugal Chiller Operational Data Recording F

13、orm Per ARI Standard 575 . 7 Form C2. Reciprocating, Screw or Scroll Chiller Operational Data Recording Form Per ARI Standard 575 . 8 Form C3. Absorption Chiller Operational Data Recording Form Per ARI Standard 575 . 9 Form C4. Pump Operational Data Recording Form Per ARI Standard 575 . 10 Form D1.

14、Sound Test Data Format . 11 ANSI/AHRI STANDARD 575-2008 1 METHOD OF MEASURING MACHINERY SOUND WITHIN AN EQUIPMENT SPACE Section 1. Purpose 1.1 Purpose. The purpose of this standard is to establish a uniform method of measuring and recording the Sound Pressure Level of machinery installed in a mechan

15、ical equipment space. It is not the intent of this standard to be used for the sound rating of equipment. 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 subj

16、ect to review and amendment as technology advances. Section 2. Scope 2.1 Scope. This standard applies to water chilling systems, pumps and similar operating machines and parts thereof, which for reasons of size or operating characteristics are more practically evaluated in situ. Section 3. Definitio

17、ns All terms in this document 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 “A”-Weighted Sound Pressure Level. The measured value obtained with a sound

18、level meter using its “A“-weighting network. 3.2 Key Measurement Points. Points located on the measurement parallelepiped at the center of each vertical plane. 3.3 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 st

19、andard 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 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

20、.5 Operating Conditions. Those conditions specified for a particular installation. In general, they are those parameters listed in the job specification sheets for the particular equipment. Examples of parameters to be recorded are found on data forms in Appendix C. 3.6 Representative “A”-Weighted S

21、ound Pressure Level. An average “A”-Weighted Sound Pressure Level from a measurement made with a majority of measurement locations not affected by nearby reflective surfaces. 3.7 Representative High Limit “A“-Weighted Sound Pressure Levels. An average “A”-Weighted Sound Pressure Level from a measure

22、ment made with a majority of measurement locations affected by reflections from nearby surfaces. The value represents an upper bound to the representative “A”-weighted value. 3.8 Representative High Limit Octave Band Sound Pressure Level. An average Octave Band Sound Pressure Level calculated from a

23、 measurement made with more than two key measurement locations affected by reflections from nearby surfaces. 3.9 Representative Octave Band Sound Pressure Levels. An average Octave Band Sound Pressure Level calculated from a measurement made with two or less key measurement locations affected by ref

24、lections from nearby surfaces. ANSI/AHRI STANDARD 575-2008 2 3.10 “Shall“ or “Should.“ “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 Sh

25、ould. “Should“ is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.11 Sound Pressure Level. The Sound Pressure Level (Lp), in decibels (dB), of a sound is 20 times the logarithm to the base 10 of the ratio of a given pressure to a reference pressure. Th

26、e reference pressure (Po) used in this standard is 20 micropascals. Lp= 20log10(p/Po) where p is the measured RMS (root mean square) sound pressure, Pa. 3.11.1 One-Third Octave Band Sound Pressure Level. A Sound Pressure Level measured when using a one-third octave band filter as defined in Section

27、3.4. 3.11.2 Octave Band Sound Pressure Level. A Sound Pressure Level measured when using an octave band filter as defined in Section 3.3. 3.12 Uncertain Measurement. A point where sound energy of other sources causes the observed value to be above its true value. 3.13 Valid Measurement. A point wher

28、e other equipment or adjacent surfaces do not significantly affect the value observed. Section 4. Instruments 4.1 Sound Level Meter. A meter meeting the requirements of the Type 1 meter described in ANSI S1.4 is to be used. 4.2 Frequency Analyzer. An octave or one-third octave band filter set meetin

29、g the requirements for Class II or III filters respectively, of ANSI S1.11 is to be used. 4.3 Calibration. During each series of measurements, an acoustical calibrator with an accuracy of 0.5 dB shall be applied to the microphone for checking the calibration of the entire measuring system at one or

30、more frequencies over the frequency range of interest. The calibrator shall be checked at the manufacturers recommended intervals or at least once every year to verify that its output has not changed. In addition, an electrical calibration of the instrumentation system over the entire frequency rang

31、e of interest shall be performed periodically as recommended by the manufacturer, but at intervals of not more than two years. Section 5. Sound Measurements and Calculation Procedures 5.1 Measurements. 5.1.1 Measurement Points. The measurement points shall be determined relative to a reference paral

32、lelepiped, which is the smallest imaginary rectangular parallelepiped that will enclose the machine (Figure 1). Minor projections from the machine are disregarded in determining the size of the reference parallelepiped. The measurement points shall be positioned on the surface of a measurement paral

33、lelepiped whose planes are one meter out from the vertical sides of the reference parallelepiped. Key Measurement Points are located at the center of each vertical plane of the measurement parallelepiped. The remaining measurement points are at one meter intervals on the measurement planes starting

34、from the key points. All measurement points are at a height of 1.5 meters from the floor. If the shortest distance between two measurement points at a corner of the measurement parallelepiped is less than one meter, the point nearest to the corner shall be eliminated. The total number of points on t

35、he measurement parallelepiped is N. ANSI/AHRI STANDARD 575-2008 3 5.1.2 Operation of Sound Level Meter. The sound level meter shall be used in the slow response position. The instrument manufacturers recommendations shall be followed in using the meter and in determining the correct microphone orien

36、tation for the flattest frequency response. 5.1.3 Data to be Taken. “A”-weighted sound pressure level measurements shall be taken at all measurement points. Octave band measurements (63 through 8000 Hz Octave Bands) shall be made at the four Key Measurement Points. A full set of measurements shall b

37、e taken with the test unit operating. A second full set of data shall be obtained with the test unit off and all other equipment in the area operating as before to establish the background sound levels. 5.1.4 Valid Measurement Points. A valid measurement point cannot be closer than one meter to a wa

38、ll or other plane surface larger than 1 square meter. A measurement shall not be recorded at any measurement point that does not meet this criterion. The number of invalid measurement points is N1. 5.1.5 Pure Tones. When pure tones are generated by the operating machine, interference patterns may af

39、fect the measured values. If the “A”-Weighted Sound Pressure Level or any Octave Band Sound Pressure Level varies 6 dB or more within an area of 0.5 meter radius of the measuring point and on the surface of the measurement parallelepiped, the highest and lowest values observed within this area shall

40、 be recorded. If variations are less than 6 dB, the value obtained at the specified measurement point shall be recorded. Figure 1. Test Unit Measurement Points ANSI/AHRI STANDARD 575-2008 4 5.2 Calculation Procedures. 5.2.1 Uncertain Measurements Due to Background Noise. Any “A“-Weighted or Octave B

41、and Sound Pressure Level taken with the test unit operating must be at least 6 dB above the corresponding level with the test unit off and other equipment operating. Any level which does not meet this criterion shall be marked uncertain by the use of an asterisk (*). The number of uncertain measurem

42、ent points is NU. 5.2.2 Pure Tones. Where the highest and lowest values were recorded for a measurement point as specified in 5.1.5, the value used in the calculations for this point shall be the highest value minus 3 dB. 5.2.3 Representative “A“-Weighted Sound Pressure Level. If half or more of the

43、 measurement points remain (that is, if N - NU- N1 N/2) after applying the limitations of 5.1.4 and 5.2.1, the Representative “A“- Weighted Sound Pressure Level (AR) shall be calculated using Equation 1. However, if less than half remain, the Representative High Limit “A”-Weighted Sound Pressure Lev

44、el shall be calculated per 5.2.5. 5.2.4 Representative Octave Band Sound Pressure Levels. If two or more key measuring points remain after applying the limitations of 5.1.4 and 5.2.1, the Representative Octave Band Sound Pressure Levels (OBR) shall be calculated using Equation 1. However, if less th

45、an two remain the Representative High Limit Octave Band Sound Pressure Level shall be calculated per 5.2.6. 5.2.5 Representative High Limit “A“-Weighted Sound Pressure Levels. If half or more of the measurement points can be obtained by adding the uncertain to the valid measurement points (that is,

46、if N - N1 N/2), then a Representative High Limit “A“-Weighted Sound Pressure Level (AH) can be calculated using Equation 1 below with NU= O. If this criteria cannot be met, neither a Representative “A”-Weighted Sound Pressure Level nor Representative High Limit “A“- Weighted Sound Pressure Level can

47、 be obtained. 5.2.6 Representative High Limit Octave Band Sound Pressure Level. If two or more Key Measurement Points can be obtained by adding the uncertain points to the valid measurement points a representative high limit Octave Band Sound Pressure Level Octave Band Sound Pressure Level (OBH) can

48、 be calculated using Equation 1. If this criteria cannot be met, neither Representative Octave Band Sound Pressure Level nor Representative High Limit Octave Band Sound Pressure Levels can be obtained. 5.2.7 Sound Pressure Level Averaging Equation. L = 10log10in/ 10Li = 110- 10log10n 1 Where: L = Re

49、presentative or high limit sound pressure level logarithmic average rounded off to the nearest 0.5 dB) Li = Sound Pressure Level at the measured points n = Number of points to be averaged = (N - NU- N1) Section 6. Machinery Sound Specifications and Data Presentation 6.1 Sound Level Specifications. Information required for specifying machinery sound levels should include the following: a. Machine description. b. Desired Representative “A”-Weighted Sound Pressure Level (AR). c. If desired, optional Representative Octave Band Sound Pressure L