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GB/T 2888-2008: Methods of noise measurement for fans blowers compressors and roots blowers Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 2888: Historical versions
Similar standardsGB/T 2888-2008: Methods of noise measurement for fans blowers compressors and roots blowers---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT2888-2008GB ICS 23.120 J 72 National Standard of the People’s Republic of China GB/T 2888-2008 Replacing GB/T 2888-1991 Methods of noise measurement for fans blowers compressors and Roots blowers Issued on. JULY 9, 2008 Implemented on. FEBRUARY 1, 2009 Issued by. State Administration for Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of China. Table of ContentsForeword... 3 1 Scope... 5 2 Normative references... 5 3 Terms, symbols and units... 5 4 Measurement items... 8 5 Measurement condition... 8 6 Measuring instruments, equipment, rack and its requirements... 9 7 Measuring device... 9 8 Measuring procedure... 10 9 Measuring method... 10 10 Processing of measurement data... 20 11 Measurement reports... 22 Annex A... 24 Annex B... 33ForewordThis Standard is the revision to GB/T 2888-1991 Methods of noise measurement for fans blowers compressors and Roots blowers. Compared with GB/T 2888-1991, the changes of the main technical contents of this Standard are as follows. — Revise the title “Main Content and Scope of Application” to “Scope”. — Reconfirm the validity of the reference standards, and add corresponding standards. — Revise the title “Code” to “Unit” in Chapter 3. — Increase the fans sound source of free inlet and free outlet in 3.2, and combine the notes of icons and figures. — The statement “When carrying out outlet aerodynamic performance test of fans” specified in 9.2.1.1 is revised as “When carrying out performance test of free inlet and pipeline outlet of fans”, and icons for description are added. — The statement “When carrying out inlet aerodynamic performance test of fans” specified in 9.2.1.2 is revised as “When carrying out performance test of pipeline inlet and free outlet of fans”, and icons for description are added. — The statement “When carrying out inlet and outlet aerodynamic performance test of fans” specified in 9.2.1.3 is revised as “When carrying out performance test of pipeline inlet and pipeline outlet of fans”, and icons for description are added. The statement “Measure the air outlet radiation noise from the vent duct. The measuring position D is at the 45° direction from the air outlet axis. The distance from the outlet center is the standard length. The measurement position shall be selected at the area without airflow vortex”. — Add icons’ noted in 9.2.1.4, 9.2.1.5 and 9.2.2. — In 10.2.1, when the test speed n is different from rated speed n0, the sound pressure level conversion formula is modified. — In 10.2.2, when the atmospheric pressure and the temperature are significantly different with that in the standard state, the sound pressure level conversion formula is modified. — Add A-sound-level calculation formula of fans noise in 10.2.3. — Units and icons’ notes of some parameters in the previous standard are modified. Annex A and Annex B of this Standard are informative. This Standard was proposed by China Machinery Industry Federation. This Standard shall be under the jurisdiction of National Technical Committee on Fans of Standardization Administration of China Drafting organizations of this Standard. Shenyang Blower (Group) Co., Ltd., Beijing Shiji Jingye Noise Vibration Control Technology Co., Ltd., and Changsha Blower Co., Ltd. Main drafters of this Standard. Chen Zhongcai, Shao Bin, Zhu Guixiu, Jiang Yunzhu, Xiao Binshi, and Wang Dongguo. The previous standard replaced by this Standard are as follows. — GB 2888-1982, GB/T 2888-1991. Methods of noise measurement for fans blowers compressors and Roots blowers 1 Scope This Standard specifies the noise measuring methods of the A-sound-level and sound pressure level. And it also specifies the noise measuring methods of the sound power level. This Standard applies to noise measurement for fans, turbo-blowers, turbo-compressors (hereinafter referred to as fans) and Roots blowers. 2 Normative references The articles contained in the following documents have become part of this Standard when they are quoted herein. For the dated documents so quoted, all the modifications (excluding corrections) or revisions made thereafter shall not be applicable to this Standard. For the undated documents so quoted, the latest editions shall be applicable to this Standard. GB/T 1236 Industrial fans-Performance testing using standardized airways GB/T 3947 Acoustical terminology GB/T 10178 Industrial fans-performance testing in situ (GB/T 10178-2006, ISO 5802. 1997, IDT) JB/T 3165 Thermodynamic performance test for centrifugal & axial blowers and compressor 3 Terms, symbols and units 3.1 A-sound-level With A-sound-level meter or other measuring instrument that is equivalent, the noise level measured by A-weighting network is called A-sound-level, expressed as LA. The unit is Decibel, with unit symbol of dB. In order to make it clear, this Standard uses dB(A) to express A-characteristic weighting. 3.2 Sound source The sound sources generated by enclosure, inlet, outlet and other sources of the fans and Roots blowers. The specific positions of the sound sources (indicated by X) are shown in Figure 1-7. 3.3 Standard sound source Standard sound source is the sound source that has very stable output and good omni- direction within the range of the measurement frequency, and it is calibrated in anechoic chamber or reverberation chamber. 4 Measurement items Under the operating conditions specified, measure A-sound-level and the frequency-band sound pressure level of fans and Roots blowers. 5 Measurement condition 5.1 Measurement environment 5.2 Operating conditions In general, noise shall be measured under the condition of rated speed and rated flow. It can also be measured under other conditions as agreed by the user. However, the specific operating conditions shall be recorded clearly. 6 Measuring instruments, equipment, rack and its requirements Measuring instruments are sound level meter and octave frequency-band filters or the equivalent instruments. Sound level meter and octave frequency-band filters shall comply with the relevant standards. 7 Measuring device The measuring devices of fans and Roots blowers shall comply with the performance testing method of corresponding standards. When installing, it shall meet the following requirements. 8 Measuring procedure Generally, aerodynamic performance test is simultaneously conducted with noise measurement of fans and Roots blowers. Noise measurement for each operating point shall be simultaneously measured with the corresponding measured values of aerodynamic performance. When it is tested on site, it can be measured in operating condition. 9 Measuring method 9.1 Measuring steps 9.1.1 The weighting network of sound level meter shall use Gear A. 9.2 Location of measuring point 9.2.1 Location of measuring point of the fans 9.2.1.1 When carrying out performance test of free inlet and pipeline outlet of fans, measure the air inlet radiation noise. The measuring point S is located on the air inlet axis, with a distance of a standard length away from the air inlet center. It is shown in Figure 8 – Figure 14. 9.2.2 Measuring point location of enclosure sound of Roots blowers, turbo- blowers and compressors 9.3 Height of measuring point If the height of measuring points of above fans and Roots blowers is less than 1m from ground, measure at the height of 1m. The absolute distance between the measuring points and the sound sources is equal to the standard length. 10 Processing of measurement data 10.1 Recording method The measuring devices and positions shall be recorded in the measuring results. And the noise shall be known clearly that whether it is generated from the openings of the inlet and outlet of the fans or from the enclosure. For enclosure noise of the fans and the Roots blowers, the average noise level shall be calculated according to the measuring point locations C1, C2..., based on Formula (1). 10.2 Conversion formula 10.2.1 When measuring the noise from the fans inlet and outlet (see 9.2.1.1-9.2.1.3) and when the test speed n and the rated speed n0 are different, the sound pressure level Lpn0 is converted according to formula (2). 10.2.2 Under normal circumstances, the effects of temperature and atmospheric pressure on sound pressure level Lp shall not be considered. However, when the atmospheric pressure and temperature are significantly different with that in standard state, the sound pressure level Lp0 is converted according to formula (3). 10.2.3 Ratio A-sound-level calculation formula of fans noise. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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