GB/T 21231.2-2018 Acoustics Measurement of radiated air noise and induced structural vibration of small ventilation devices Part 2: Measurement of structural vibration GB/T21231.2-2018 |tt||Standard compression package decompression password: www.bzxz.net
This part is applicable to the vibration level measurement of small ventilation devices. According to the provisions of GB/T 21231.1-201x, the installation area of ​​the full-scale test box for such small ventilation devices is less than 0.48m×0.90m, and the installation area of ​​the reduced-scale 1/2 test box is less than 0.18m×0.3m. This part is applicable to various types of small ventilation devices that can be installed in a test box that meets the provisions of GB/T 21231.1-201x and has self-supporting and inlet and outlet end faces.

ICS17.140
National Standard of the People's Republic of China
GB/T21231.2—2018/ISO10302-2:2011AcousticsMeasurement of airborne noise emitted and structure-borne vibration induced by small air-moving devices-Part 2:Structure-borne vibration measurements(ISO10302-2:2011IDT)
Released on 2018-03-15
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of China
Implementation on 2018-10-01
Normative reference documents
Terms and definitions
Descriptive quantity
Measurement uncertainty
Design and performance requirements of test fixture
Operation of ventilation device
Measurement steps·
Test report
Appendix A (Informative Appendix) Recommended report data format
Appendix B (Informative Appendix)
Recommended voltage for testing variable speed ventilation device Appendix C (Informative Appendix)
Appendix D (Informative Appendix)
References
GB/T2 1231.2—2018/ISO10302-2:20118
Technical specification of structural vibration acceleration levels of ventilation devices Guide to the evaluation of measurement uncertainty
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GB/T21231.2—2018/ISO10302-2:2011GB/T21231 "Acoustic small ventilation devices - Measurement of air noise and induced structure-borne vibration" consists of the following two parts: Part 1: Measurement of air noise;
Part 2: Measurement of structure-borne vibration.
This part is the second part of GB/T21231
This part was drafted according to the rules given in GB/T1.1-2009. This part uses the translation method and is equivalent to ISO10302-2:2011 "Acoustic small ventilation devices - Measurement of air noise and structure-borne vibration emitted by part 2: Measurement of structure-borne vibration". The Chinese documents that have consistent correspondence with the international documents normatively referenced in this part are as follows: GB/T3240-1982 Common frequencies in acoustic measurements (neqISO266:1975) GB/T3241-2010 Electroacoustic octave and fractional octave filters (IEC61260:1995MOD) GB/T14412-2005 Mechanical installation of mechanical vibration and shock accelerometers (ISO5348:1998IDT) - GB/T20485.11-2006 Vibration and shock sensor calibration method Part 11: Absolute vibration calibration by laser interferometry (ISO16063-11:1999, IDT) GB/T20485.21-2007 Vibration and shock sensor calibration method Part 21: Calibration by vibration comparison method (ISO16063-21:2003.IDT).
This part is proposed by the Chinese Academy of Sciences.
This part is under the jurisdiction of the National Technical Committee for Acoustic Standardization (SAC/TC17). Drafting units of this part: Shenzhen Zhongya Electromechanical Industry Co., Ltd., Institute of Acoustics, Chinese Academy of Sciences, Shanghai Shenhua Acoustic Equipment Co., Ltd., Tongji University, Anhui Weiwei Rubber Parts Group Co., Ltd., Beijing Labor Protection Science Research Institute, Changsha Aobang Environmental Protection Industry Co., Ltd., Shanghai Jiaotong University, Zhejiang University, China Institute of Metrology, Shanghai Xinhuajing Environmental Protection Engineering Co., Ltd., Northwestern Polytechnical University, Shanghai Academy of Environmental Sciences, Dalian Mingri Environmental Engineering Co., Ltd., etc. The main drafters of this part: Fang Qingchuan, Li Xiaodong, Yang Jun, Cheng Mingkun, Lv Yadong, Mao Dongxing, Yu Wuzhou, Zhang Mingfa, Hu Wencheng, Li Xiaokuan, Mo Jianyan, Li Zhiyuan, Li Jun, Jiang Weikang, Zhai Guoqing, He Longbiao, Chen Ke'an, Wang Bing, Liu Yunfeng, Wu Daozhong, Zhou Yude, Zhu Wenying, Liu Danxiao, Xu Xin.
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1 Scope
GB/T21231.2—2018/ISO10302-2:2011 Acoustics Measurement of radiated air noise and induced structural vibration of small ventilation devices
Part 2: Measurement of structural vibration
This part of GB/T21231 is applicable to the vibration level measurement of small ventilation devices. According to the provisions of GB/T21231.1-2018, for such small ventilation devices, the installation area of ​​the full-scale test box is less than 0.48m×0.90m, and the installation area of ​​the reduced-scale 1/2 test box is less than 0.18 mX0.3m.
This part is applicable to various types of small ventilation devices that can be installed in a test box that complies with the provisions of GB/T21231.1-2018 and has a self-supporting and outlet end face.
The procedures specified in this part detail the methods for measuring the vibration levels caused by the common structures of small ventilation devices used for information and communication equipment. The methods specified in this part can be used to determine the vibration levels of a single small ventilation device. If the vibration levels are measured from a number of small ventilation devices in a series, these data can be used to determine the statistical values ​​of the vibration levels of the series of products. 2 Normative references
The following documents are indispensable for the application of this document. For any dated referenced document, only the dated version applies to this document. For any undated referenced document, the latest version (including all amendments) applies to this document. GB/T21231.1-2018 Acoustics Measurement of radiated airborne noise and induced structural vibration of small ventilation devices Part 1: Measurement of airborne noise (ISO10302-1:2011, IDT) ISO266 Acoustics—Preferred frequencies ISO5348 Mechanical vibration and shock—Mechanical mounting of accelerometers
ISO16063-11 Methods for the calibration of vibration and shock transducers Part 11: Primary vibration calibration by laser interferometry
ISO16063-21 Methods for calibration of vibration and shock transducers Part 21: Vibration calibration by comparison to a reference sensor Reference transducer)IEC61260 Electroacoustics—Octave-band and fractional octave-band filters
ISO/IECGuide98-3 Uncertainty in measurement-Part 3: Guide to the expression of uncertainty in measurement (GUM: 1995)3 Terms and definitions
GB/T21231.1-2018 and the following terms and definitions apply to this document. 1
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GB/T21231.2—2018/ISO10302-2:20113.1
Vibration acceleration level vibratoryaccelerationlevelLa
The logarithm to the base 10 of the ratio of the square of the acceleration to the square of the reference acceleration, in decibels (dB). La=10lgl
Where:
a. —reference acceleration, in meters per second squared (m/s\), a. =1um/s2. Note 1: The frequency band width must be indicated; for example, all frequency bands or 1/3 octave bands within the frequency range of interest. Note 2: Some standards may use other reference acceleration values. Note 3: In this section, "vibration acceleration level" is often referred to as "acceleration level". 3.2
Test frequency range frequency rangeof interest includes the 1/3 octave band specified in ISO266 within the frequency range of 25Hz to 5kHz. 3.3
Information technology and telecommunications equipment Information processing equipment and its components for use in homes, offices, computer sites, communication stations or similar environments. [See ISO 7779:2010 [3], 3.1.3] NOTE This standard is intended to support designers of information technology and telecommunications equipment. 4 Descriptive quantities
(1)
The primary description of the vibration level caused by a small ventilation device is the energy average of the unweighted total vibration acceleration level at the measurement point within the test frequency range (see 3.2). This frequency range includes most of the frequencies of airborne noise radiated by small ventilation devices in GB/T 21231.1-2018, and also adds a low-frequency range of 1/3 octave bands with a center frequency of 25 Hz to 80 Hz. The description is based on unweighted 1/3 octave band acceleration levels. Although the test apparatus and procedures of this standard can also be used in conjunction with a narrowband frequency analyzer for more detailed studies, a narrowband analyzer is not required here. NOTE Accelerations can be measured conveniently because non-invasive lightweight accelerometers are widely available and simple to operate. The unweighted total acceleration level was chosen because it is simple to measure and correlates well with the A-weighted structure-borne noise level radiated from the structure (see references [7] and [11]). The A-weighted structure-borne noise level generated by structural vibration is determined by: a) converting the acceleration to velocity; b) correcting for the radiation efficiency of the structure; and c) performing an A-weighting. To a first order approximation, the three results of these calculations as functions of frequency cancel each other out, except for the constant. This allows the unweighted total acceleration level to be considered as a simple measure of the A-weighted structure-borne noise caused by the fan. 5 Measurement uncertainty
The uncertainty of the measurement results shall be estimated in accordance with the requirements of this standard, preferably in accordance with ISO/IEC Guide 98-3. In the record, the expanded uncertainty and the corresponding coverage factor shall be given in accordance with ISO/IEC Guide 98-3. Annex D gives guidance on the determination of the expanded uncertainty.
If measurements are made in a laboratory according to this standard, the existing knowledge is not sufficient for the full application of ISO/IEC Guide 98-3. Therefore, it is recommended to use the reproducibility standard deviation given in Table 1 in the test report temporarily. Multiply the value by the coverage factor 2 to obtain an estimate of the expanded uncertainty with a confidence probability of 95%.
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GB/T21231.2—2018/ISO10302-2:2011 Table 1 Estimated values ​​of the reproducibility standard deviation of the vibration acceleration level of ventilation equipment determined according to GB/T21231 1/3 octave band center frequency
80~160
200~5000
20~5000
Reproducibility standard deviation. RO
Full frequency band
Repeatability standard deviation.
NOTE 1: These estimates were obtained in multiple laboratories using three half-scale or full-scale test chambers for five types of small ventilation devices (three tubular axial fans and two forward curved blade centrifugal fans) with capacities ranging from 0.0016 m/s to 0.137 m/s, using five different operators in two laboratories following the guidelines of ISO 5725 [2] (see references [7]-[11]). NOTE 2: The reproducibility standard deviation reflects the cumulative effect of the various measurement uncertainty components, including laboratory differences, but excluding differences in acceleration levels between samples. For laboratories using the same samples and the same measurement conditions, the repeatability standard deviation is less than the reproducibility standard deviation. NOTE 3: These values ​​apply to small ventilation devices that are intact and in stable operation under the test conditions specified in this standard. 6 Design and performance requirements of test fixtures
6.1 General design requirements
6.1.1 Overview
The design of the test box shall comply with the requirements of GB/T21231.1-2018, but the mounting plate specified in GB/T21231.1-2018 shall be replaced with the damping plate specified in 6.2 of this part.
6.1.2 Flow rate
The flow rate of the fan installed in the test box under the test conditions shall not be Greater than the calculated value of formula (2): qv.max
Where:
6.1.3 Static pressure
The maximum volume flow of the scaled test box, in cubic meters per second (m2/s); the maximum volume flow of the full-scale test box, in cubic meters per second (m/s), qv.0=1m2/s;..(2)
The nominal air volume of the full-scale test box defined in GB/T21231.1-2018. The unit is cubic meters (m*), V. =1.3m
The nominal air volume of the scaled test box, in cubic meters per second (m2/s). The static pressure of the ventilation device in which the test box is running should not exceed 750Pa. 6.1.4 Air/pressure distribution
All relevant geometric dimensions (such as the location and size of the mounting plate or outlet) shall be consistent with the full-scale test box specified in GB/T21231.1-20183
GB/T21231.2-2018/ISO10302-2:2011.
6.2 Damping panels
The technical specification of the damping panel is that the mechanical admittance level measured at the center of the panel with a size of 1m2, free suspension support at the two corners and no fan mounting holes is -45dB (reference value: 1m/Ns) in the frequency range of 25Hz to 5000Hz. The mechanical admittance level should be measured in accordance with ANSI/ASAS2.32[17. The tolerances for the mechanical admittance level in the frequency range 25 Hz to 100 Hz are ±8 dB, ±4 dB for 100 Hz to 200 Hz and ±2 dB for 200 Hz to 5000 Hz. These tolerances ensure that the panel has sufficient damping to prevent the structure from being excited. 6.3 Mounting area
This standard covers the measurement of vibration levels for small ventilation units with a maximum mounting area of ​​0.48 m x 0.90 m for full-scale test chambers. For all sizes of test chambers, the distance from the edge of the maximum mounting base of the ventilation unit to the edge of the damping plate is constant: 0.06 m from the top and bottom edges and 0.15 m from the side edges (for a 1/2 scale test chamber, the maximum mounting area is 0.18 m x 0.30 m). 7 Mounting
Orientation of ventilation units
The air outlet of the ventilation unit should be mounted on the damping plate as far as possible; if other mounting methods are used, they should be stated in the report. 7.2 Installation of ventilation devices
The ventilation device shall be installed on the damping plate that meets the requirements of 6.2. Unless a special mounting connection device is evaluated, the ventilation device shall be connected to the damping plate with through screws. Refer to the ventilation device manufacturer's instructions. The screws shall be tightened to the torque specified by the manufacturer. In the absence of relevant manufacturer's instructions, it is recommended to use M3.5 (UNC6-32) bolts and tighten them to a torque of 0.35N·m. In the case of a ventilation device housing with multiple mounting holes in a row, only the holes directly opposite or closest to the damping plate can be used. 7.3 Damper Plate Openings
The inlet and outlet openings of the test chamber for the ventilation device shall be specified by the manufacturer. In the absence of manufacturer's instructions, the openings shall be at least as large as the inlet and outlet openings of the ventilation device and shall be smooth and free of burrs. The ventilation device shall be mounted directly on the damping plate without any seals or gaskets. 8 Operation of the Ventilation Device www.bzxz.net
8.1 Input Power
8.1.1 AC Ventilation Devices
Unless otherwise specified, the ventilation device shall operate within the rated power linear frequency range, with the following variations within 1%: a) the rated voltage of the ventilation device (if stated); or b) the average voltage within the specified range.
For a power supply with more than two phases, the phase-to-phase voltage shall not vary by more than 1% of the rated voltage. The voltage conditions used shall be recorded 8.1.2 DC ventilation devices
The ventilation device shall be operated within the following voltage range of ±1%: a) rated nominal voltage;
rated maximum voltage;
rated minimum voltage.
GB/T21231.2—2018/ISO10302-2:2011If the fan is operated at variable speed, it is recommended but not mandatory to use the voltage values ​​given in Appendix B. In this case, the voltage conditions should be recorded. 8.2 Operating conditions
Unless otherwise specified, the ventilation device shall be tested at three operating points for each voltage and frequency required in 8.1. The corresponding operating points are as follows:
a) adjustable outlet (slide plate) fully open; b) 80% of the maximum volume flow rate:
c) 20% of the maximum volume flow rate.
Additional tests may be run at other operating points, including the maximum full static efficiency point, in order to establish the relationship between the vibration acceleration level and the volume flow rate. Some ventilation devices (such as small tubular axial fans) may be unstable when running close to the maximum full static efficiency point. The test should not be carried out at the unstable point of operation. The operating conditions should be determined according to 7.2 of GB/T21231.1-2018. 9 Instruments
Test chamber pressure measurement
The static pressure test of ventilation devices should be consistent with GB/T21231.1-2018 9.2
Accelerometer and accelerometer system
The vibration generated by the structure should be measured by accelerometer and suitable signal conditioning equipment (accelerometer system). When installed in accordance with ISO5348 and calibrated using one or more methods specified in ISO16063-11 or ISO16063-21 (as applicable), the accelerometer system, including the influence of all signal conditioning equipment and connecting cables, should have a flat frequency response of 1.0 dB in the frequency range of 20Hz6300Hz. The accelerometer should preferably be a unidirectional accelerometer, usually a piezoelectric accelerometer. As part of the accelerometer system in direct contact with the structure, the mass of the sensor shall not exceed 3 grams. Care shall be taken to ensure that the measurement environment conditions, such as strong electric or magnetic fields, temperature or temperature transients, and the mounting method do not adversely affect the acceleration stage system during the measurement. Alternative sensors are permitted, but the performance is at least equivalent to that of piezoelectric accelerometers. NOTE 1 The mass of the accelerometer should be selected to be of a size suitable for ventilation. The accelerometer cable should be selected to minimize extraneous signals due to triboelectric effects, noise and other environmental sensitivities. NOTE 2 The frequency response of the accelerometer system at high frequencies depends on the quality of the mounting. For typical field installations, the use of beeswax is permitted. The manufacturer should specify a beeswax mounting resonant frequency of at least 25 kHz or a useful frequency range of at least 8 kHz (with a frequency response fluctuation limit of not more than 10%). 9.3 Signal Conditioner
The accelerometer system in 9.2 shall include suitable signal conditioning equipment. Typically, these equipment may include one or more of the following: charge amplifier, voltage amplifier, power supply, high-pass or low-pass filter. 9.4 Analyzer
The analyzer shall be capable of measuring the RMS acceleration level in 1/3 octave bands within the test frequency range. When combined with the accelerometer system, the complete system including the analyzer shall have a frequency response of no more than ±2.0 dB within the test frequency range. The 1/3 octave band filter shall comply with the requirements of Class 1 in IEC61260. The center frequency of the 1/3 octave band shall preferably be the frequency specified in ISO266. 9.5 Calibration
The calibration of the accelerometer, the vibration calibrator used for routine calibration, and all instruments in the system is recommended to be calibrated annually and at least once every two years. The acceleration and vibration calibrator shall be calibrated in accordance with the procedures specified in ISO16063-11 or ISO16063-21 (as applicable) and shall be traceable to national metrological standards. Other instruments should be calibrated according to the manufacturer's instructions. 10 Measurement procedures
10.1 Preparation
The procedures are as follows:
Record the name, model, serial number, dimensions, nameplate data, date code, and complete description of the ventilation device to be testeda) Obtain the aerodynamic performance curve of the ventilation device according to GB/T 21231.1-2018;c) Measure the ambient temperature, relative humidity, and atmospheric pressure;d) Zero the test chamber manometer;
Calibrate the accelerometer and measuring instruments according to 9.5; Measure the background acceleration level according to 10.4.2; Determine the average value according to 10.4.1.
The operating test of ventilation equipment
procedures are as follows:
Install the ventilation equipment on the test chamber in accordance with clause 7;a)
Preheat until the temperature at the fan outlet is stable, usually 15 min; adjust the voltage in accordance with 8.1;
Adjust the slider in accordance with 8.2 to obtain the desired operating point;d)
Measure the acceleration level at each accelerometer point for the time period specified in 10.9;f)
Record the data in accordance with clause 11:
Repeat steps c) to f) for the required additional operating points. 10.3 Calibration operation
The calibration check shall be carried out at the beginning and end of each series of measurements and at least once a day, and the results shall be kept as part of the test report. The series of instruments calibrated at this time shall be the same as those used for the vibration acceleration level measurement of the ventilation equipment, and the sensors shall be adjusted in accordance with the manufacturer's instructions.
The accelerometers shall be calibrated by a vibration calibrator or similar device in accordance with the manufacturer's instructions. This calibration only needs to be performed at one frequency within the test frequency range, preferably with an amplitude greater than or equal to the measured value of the ventilation device to be tested. The signal amplitude generated by the accelerometer placed in the vibration calibrator position should be read on the instrument or analyzer used for ventilation device measurement. The output amplitude can be adjusted by gain switch, potentiometer or data acquisition software so that the final readout data meets the manufacturer's specification of 0.5 dB deviation in the vibration calibrator amplitude. 10.4 Measurement
10.4.1 Running measurement and data averaging
For each operating point specified in 8.2, the acceleration level is measured in a 1/3 octave band under the duration conditions specified in 10.9. The measurement includes each accelerometer measurement point specified in 10.8 and each voltage condition specified in 8.1. The measurement results should be rounded to 0.1 dB.
NOTE 1: This standard also applies to test techniques using non-contact methods, such as laser vibrometers. For each voltage and static pressure state, the unweighted total acceleration level L at each accelerometer measuring point is calculated from the 1/3 octave band acceleration level using formula (3):0dB flat frequency response. Accelerometers should be unidirectional, usually piezoelectric. As part of the accelerometer system in direct contact with the structure, the mass of the sensor should not exceed 3 grams. Care should be taken to ensure that the measurement environment conditions, such as strong electric or magnetic fields, temperature or temperature transients, and the installation method do not have an adverse effect on the acceleration level system during the measurement. Alternative sensors are allowed, but the performance is at least the same as that of piezoelectric accelerometers. Note 1: The mass of the accelerometer should be selected to be of a size suitable for ventilation. The accelerometer cable should be selected to minimize the generation of irrelevant signals due to triboelectric effects, noise and other environmental sensitivities. Note 2: The frequency response of the accelerometer system at high frequencies depends on the quality of the installation. For typical field installations, the use of beeswax is allowed. The manufacturer should specify that the beeswax installation resonant frequency is at least 25kHz or the useful frequency range is at least 8kHz (the limit of frequency response fluctuation does not exceed 10%). 9.3 Signal Conditioner
The accelerometer system in 9.2 should include appropriate signal conditioning equipment. Typically, these equipment may include one or more of the following: charge amplifier, voltage amplifier, power supply, high-pass or low-pass filter. 9.4 Analyzer
The analyzer should be able to measure the root mean square acceleration level in the test frequency range using 1/3 octave bands. When combined with the accelerometer system, the complete system including the analyzer should have a frequency response of no more than ±2.0dB in the test frequency range. The 1/3 octave band filter should comply with the requirements of Class 1 in IEC61260. The center frequency of the 1/3 octave band should preferably be the frequency specified in ISO266. 9.5 Calibration
Calibration of the accelerometer, the vibration calibrator used for routine calibration, and all instruments in the system are recommended to be calibrated once a year, or at least once every two years. Acceleration and vibration calibrators shall be calibrated in accordance with the procedures specified in ISO 16063-11 or ISO 16063-21 (as applicable) and shall be traceable to national metrological standards. Other instruments should be calibrated according to the manufacturer's instructions. 10 Measurement procedures
10.1 Preparation
The procedures are as follows:
Record the name, model, serial number, dimensions, nameplate data, date code, and complete description of the ventilation device to be testeda) Obtain the aerodynamic performance curve of the ventilation device according to GB/T 21231.1-2018;c) Measure the ambient temperature, relative humidity, and atmospheric pressure;d) Zero the test chamber manometer;
Calibrate the accelerometer and measuring instruments according to 9.5; Measure the background acceleration level according to 10.4.2; Determine the average value according to 10.4.1.
The operating test of ventilation equipment
procedures are as follows:
Install the ventilation equipment on the test chamber in accordance with clause 7;a)
Preheat until the temperature at the fan outlet is stable, usually 15 min; adjust the voltage in accordance with 8.1;
Adjust the slider in accordance with 8.2 to obtain the desired operating point;d)
Measure the acceleration level at each accelerometer point for the time period specified in 10.9;f)
Record the data in accordance with clause 11:
Repeat steps c) to f) for the required additional operating points. 10.3 Calibration operation
The calibration check shall be carried out at the beginning and end of each series of measurements and at least once a day, and the results shall be kept as part of the test report. The series of instruments calibrated at this time shall be the same as those used for the vibration acceleration level measurement of the ventilation equipment, and the sensors shall be adjusted in accordance with the manufacturer's instructions.
The accelerometers shall be calibrated by a vibration calibrator or similar device in accordance with the manufacturer's instructions. This calibration only needs to be performed at one frequency within the test frequency range, preferably with an amplitude greater than or equal to the measured value of the ventilation device to be tested. The signal amplitude generated by the accelerometer placed in the vibration calibrator position should be read on the instrument or analyzer used for ventilation device measurement. The output amplitude can be adjusted by gain switch, potentiometer or data acquisition software so that the final readout data meets the manufacturer's specification of 0.5 dB deviation in the vibration calibrator amplitude. 10.4 Measurement
10.4.1 Running measurement and data averaging
For each operating point specified in 8.2, the acceleration level is measured in a 1/3 octave band under the duration conditions specified in 10.9. The measurement includes each accelerometer measurement point specified in 10.8 and each voltage condition specified in 8.1. The measurement results should be rounded to 0.1 dB.
NOTE 1: This standard also applies to test techniques using non-contact methods, such as laser vibrometers. For each voltage and static pressure state, the unweighted total acceleration level L at each accelerometer measurement point is calculated from the 1/3 octave band acceleration level using formula (3):0dB flat frequency response. Accelerometers should be unidirectional, usually piezoelectric. As part of the accelerometer system in direct contact with the structure, the mass of the sensor should not exceed 3 grams. Care should be taken to ensure that the measurement environment conditions, such as strong electric or magnetic fields, temperature or temperature transients, and the installation method do not have an adverse effect on the acceleration level system during the measurement. Alternative sensors are allowed, but the performance is at least the same as that of piezoelectric accelerometers. Note 1: The mass of the accelerometer should be selected to be of a size suitable for ventilation. The accelerometer cable should be selected to minimize the generation of irrelevant signals due to triboelectric effects, noise and other environmental sensitivities. Note 2: The frequency response of the accelerometer system at high frequencies depends on the quality of the installation. For typical field installations, the use of beeswax is allowed. The manufacturer should specify that the beeswax installation resonant frequency is at least 25kHz or the useful frequency range is at least 8kHz (the limit of frequency response fluctuation does not exceed 10%). 9.3 Signal Conditioner
The accelerometer system in 9.2 should include appropriate signal conditioning equipment. Typically, these equipment may include one or more of the following: charge amplifier, voltage amplifier, power supply, high-pass or low-pass filter. 9.4 Analyzer
The analyzer should be able to measure the root mean square acceleration level in the test frequency range using 1/3 octave bands. When combined with the accelerometer system, the complete system including the analyzer should have a frequency response of no more than ±2.0dB in the test frequency range. The 1/3 octave band filter should comply with the requirements of Class 1 in IEC61260. The center frequency of the 1/3 octave band should preferably be the frequency specified in ISO266. 9.5 Calibration
Calibration of the accelerometer, the vibration calibrator used for routine calibration, and all instruments in the system are recommended to be calibrated once a year, or at least once every two years. Acceleration and vibration calibrators shall be calibrated in accordance with the procedures specified in ISO 16063-11 or ISO 16063-21 (as applicable) and shall be traceable to national metrological standards. Other instruments should be calibrated according to the manufacturer's instructions. 10 Measurement procedures
10.1 Preparation
The procedures are as follows:
Record the name, model, serial number, dimensions, nameplate data, date code, and complete description of the ventilation device to be testeda) Obtain the aerodynamic performance curve of the ventilation device according to GB/T 21231.1-2018;c) Measure the ambient temperature, relative humidity, and atmospheric pressure;d) Zero the test chamber manometer;
Calibrate the accelerometer and measuring instruments according to 9.5; Measure the background acceleration level according to 10.4.2; Determine the average value according to 10.4.1.
The operating test of ventilation devices
procedures are as follows:
Install the ventilation device on the test chamber in accordance with clause 7;a)
Preheat until the temperature at the fan outlet is stable, usually 15 min; adjust the voltage in accordance with 8.1;
Adjust the slider in accordance with 8.2 to obtain the desired operating point;d)
Measure the acceleration level at each accelerometer point for the time period specified in 10.9;f)
Record the data in accordance with clause 11:
Repeat steps c) to f) for the required additional operating points. 10.3 Calibration operation
The calibration check shall be carried out at the beginning and end of each series of measurements and at least once a day, and the results shall be kept as part of the test report. The series of instruments calibrated at this time shall be the same as those used for the vibration acceleration level measurement of the ventilation device, and the sensors shall be adjusted in accordance with the manufacturer's instructions.
The accelerometers shall be calibrated by a vibration calibrator or similar device in accordance with the manufacturer's instructions. This calibration only needs to be performed at one frequency within the test frequency range, preferably with an amplitude greater than or equal to the measured value of the ventilation device to be tested. The signal amplitude generated by the accelerometer placed in the vibration calibrator position should be read on the instrument or analyzer used for ventilation device measurement. The output amplitude can be adjusted by gain switch, potentiometer or data acquisition software so that the final readout data meets the manufacturer's specification of 0.5 dB deviation in the vibration calibrator amplitude. 10.4 Measurement
10.4.1 Running measurement and data averaging
Measure the acceleration level in a 1/3 octave band for each operating point specified in 8.2 under the duration conditions specified in 10.9. The measurement includes each accelerometer measurement point specified in 10.8 and each voltage condition specified in 8.1. The measurement results should be rounded to 0.1 dB.
NOTE 1: This standard also applies to test techniques using non-contact methods, such as laser vibrometers. For each voltage and static pressure state, the unweighted total acceleration level L at each accelerometer measuring point is calculated from the 1/3 octave band acceleration level using formula (3):1dB.
Note 1: This standard also applies to non-contact test techniques, such as laser vibrometers. For each voltage and static pressure state, the unweighted total acceleration level L of each accelerometer measuring point is calculated from the 1/3 octave band acceleration level using formula (3):1dB.
Note 1: This standard also applies to non-contact test techniques, such as laser vibrometers. For each voltage and static pressure state, the unweighted total acceleration level L of each accelerometer measuring point is calculated from the 1/3 octave band acceleration level using formula (3):
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