【法规名称】
【法规编号】 79202 什么是编号？
【正 文】
第3页 CAP 400C NOISE CONTROL (AIR COMPRESSORS) REGULATIONS
|
[接上页] 7.2 Measurement of the sound pressure level LpA To measure the sound pressure level LpA, use shall be made of an instrument as defined in paragraph 5.2. If a sound level meter is used, 5 readings shall be taken at each measuring point. The mean value of these 5 readings shall be calculated in accordance with paragraph 11. If an integrating sound level meter is used, the integrating time shall be 15 seconds. 8. USE OF RESULTS 8.1 Calculation of root mean square values 8.1.1 Root mean square value at a measuring point The values obtained from the measurements referred to in paragraph 7.2 are root mean square values in time. 8.1.2 Root mean square value on the measuring surface The level corresponding to the root mean square value in space of the sound pressure levels for all the measuring points shall be calculated on the basis of the values established in accordance with paragraph 8.1.1. 8.2 Calculation of average extraneous noise level The average extraneous noise level over the measuring surface is obtained by applying the method described in paragraph 8.1.2 to the extraneous noise levels established at the different measuring points. 8.3 Calculation of the area S of the measuring surface The area S, expressed in m2, of the measuring surface is determined as follows- S = 2πR2The area of the measuring surface may be calculated approximately. It should be noted that an error of ±20% in this area gives a deviation of ±1 dB in the value of the term- 10 log10 S/So (surface level) 8.4 Calculation of the surface sound pressure level LpAm The surface sound pressure level is the level calculated in accordance with paragraph 8.1.2 and then corrected as described in paragraph 8.6. 8.5 Calculation of the sound power level LWA The sound power level LWA of the sound source is calculated by means of the following equation- LWA = LpAm + 10 log10 S/So Where- LWA = sound power level of the source tested, expressed in dB (see paragraph 3.4); LpAm = the surface sound pressure level, expressed in dB, as defined in paragraph 3.3; S = the area of the measuring surface in m2, calculated in accordance with paragraph 8.3;So = reference area of 1 m2. 8.6 Corrections to be made to measurements The average sound pressure level over the measurement surface, calculated in accordance with paragraph 8.1, shall be corrected, if necessary, to take account of the extraneous noise determined in accordance with paragraph 8.2. The correction K1 in dB, which shall be subtracted from the average sound pressure level over the measuring surface is given in the table below. Difference in dB between the sound pressure level calculated when the appliance is operating and the sound pressure level due to extraneous noise alone Correction K1 in dB less than 6 6 7 8 9 10 more than 10 no valid measurements 1.0 1.0 1.0 0.5 0.5 no correction To allow for tolerances, 5 dB(A) shall be deducted from the A-weighted sound power LWA determined for the appliance and the net result shall then be compared with the relevant standard. 9. DATA TO BE RECORDED A model report is provided in the Appendix. 10. DATA TO BE INCLUDED IN THE REPORT LAID DOWN IN PARAGRAPH 9 The data shall be reported in accordance with paragraph 9. The report shall state clearly that the sound power levels were obtained in accordance with the test conditions. It shall specify that these sound power levels are given in A-weighted dB, reference 10-12 W. 11. METHOD OF CALCULATING THE AVERAGE LEVEL CORRESPONDING TO THE ROOT MEAN SQUARE VALUE OF THE VARIOUS SOUND PRESSURE LEVELS The root mean square value of the various sound pressure levels resulting from a series of measurements made at different points on the measuring surface (root mean square in space) can be determined by the following formula- LpAm = LpAo + 10 log10 1/n i = n ∑ gii = 1 Where- LpA = the sound pressure level of the i-th measurement; LpAo = an auxiliary sound pressure level to simplify the calculation (for example, the smallest of the LpAi values);gi = the auxiliary variable for the i-th measurement- gi = 100.1 (LpAi-LpAo). APPENDIX MODEL REPORT TEST REPORT FOR AIR COMPRESSORS 1. Test Article Manufacturer ............................................................................................................... Model ..................................................... Serial No. .................................................. Description ............................................. Mass ......................................................... Type: Compressed air, hydraulic, electric, petrol(1) 2. The Compressor Length ............................................. m Width .............................................. m Height ............................................. m Mass ............................................... kg 3. Operating Conditions(1) 3.1 Operation of the drive motor Make and type ............................................................................................................. |
- 此法规有错误，我来纠正。请点击在此 提交错误内容或者您纠正的内容！