Introduction Of Noise Measurement Methods For Leather Machinery

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< p > 1.. This standard specifies that the test environment is free sound field above a reflecting plane.

The sound pressure level is measured on the measurement surface of an artificial envelope source.

The noise power level of leather making machinery (including < a href= "http://www.91se91.com" > tanning machinery < /a > leather machinery and a href= "http://www.91se91.com/news/" > leather shoes machinery < /a > hereinafter referred to as leather machinery) is determined by the engineering method of calculating the sound power level.

The data obtained are used to evaluate or compare the acoustic properties of leather machinery products.

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< p > 2. this standard is applicable to all kinds of broadband or narrow-band noise of radiation steady state, namely, a href= "http://www.91se91.com/news/index_c.asp" > leather machinery < /a >.

It is not suitable for leather machinery with linear dimension (long, wide or high) exceeding 15m of radiation impulse noise and leather machinery.

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< p > 3. the standard is compiled according to the principle of engineering method in GB/T 3767 "determination of sound power level of noise source in engineering and quasi Engineering".

The ISO 3744 "Acoustics -- the measurement of the sound power level of the voice source -- is applied to the engineering condition of the free field condition on a reflecting plane".

The terms, quantities and symbols used in the standard comply with the relevant national standards such as GB/T 3947 "acoustic terms" and "GB 3l02.7" quantity and unit of acoustics.

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< p > two, the amount of determination and uncertainty of measurement < /p >

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< p > 1., the amount needed to be measured is < /p >.

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The measurement of sound power level, other power level and directivity index of < p > A sound power level or band is not satin.

Choose according to your needs.

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< p > 2. uncertainty of measurement < /p >

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< p > leather machinery with uniform spectral density in the frequency range of 1000 to 100 ~ 10000Hz.

The standard deviation of A power level is not 2dB.

The standard deviation of measuring the frequency power of the octave band and the 1/3 frequency doubling band is not greater than that of Table 1.

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< p > Main: (1) the standard deviation reflects the cumulative effect of uncertainty caused by various factors, including the change of sound power level due to the change of leather machinery installation and operation conditions in each test.

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When p is measured outdoors, the standard deviation of the power level of the frequency doubling band with a center frequency of 63Hz is 5dB.

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< p > three, test environment requirement < /p >

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< p > 1. the test environment suitable for this standard should be a large reflecting room (usually concrete or asphalt floor), a large room above the free sound field (such as assembly workshop) or outdoor square.

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< p > 2.. No reflectors and sound absorbing objects (including personnel) can be measured on the surface.

There should be no reflectors outside the surface.

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< p > 3. when the actual test environment deviates from the ideal free field conditions, the appendix A method should be used to determine the environmental correction value K2, and the waxing and correction of the measurement results will be made. The environmental correction value K2 (or A/S value) must meet K2<2.2dB (or A/S>6).

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< p > note: definition and determination of A/S in Appendix A A2.

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< p > 4. when the sound pressure level of operation is less than 6dB, the measurement is invalid.

When the difference between the sound pressure level and the background noise pressure level is less than or equal to 10dB, correction should be made.

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< p > 5.. When the temperature of the test environment deviates from the standard environmental condition (temperature t=20 Po=100kPa, Po=100kPa), the correction value is equal to or greater than that of the standard.

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< p > (6) in outdoor tests, customs should be <6m/s (equivalent to class 4 wind) and use wind shield.

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