MAX. ALLOW. SOUND PRESS. LEVEL REQD (6.1.14)
MAX. SOUND POWER LEVEL REQ’D (6.1.14)
6.1.14 If specified, the vendor shall provide both maximum sound pressure and sound power level data per octave band for the equipment. Control of the sound pressure level (SPL) of all equipment furnished shall be a joint effort of the purchaser and the vendor who has unit responsibility. The equipment furnished by the vendor shall conform to the maximum allowable sound pressure level specified. ISO 3740[7], ISO 3744[8] and ISO 3746[9] may be consulted for guidance. {API 610}
If specified, sound level tests shall be performed as agreed between the Purchaser and the Vendor. {API 610}
NOTE: ISO 3740, ISO 3744, and ISO 3746 may be consulted for guidance. {API 610}
- For the pump skid, or any individual component, operating at full load, in a free field over a reflecting plane, the sound pressure level measured at any point on a surface 1 meter from the surface of the reference box shall not exceed 85 dBA. No positive tolerance will be allowed. {Total}
- If a noise test is specified, ISO 3744 will be used as a basis for sound pressure measurement. {Total}
ISO 3744: Determination of sound power levels of noise sources using sound pressure.
- A parallelepiped measurement surface (ISO 3744 paragraph 7.2.4) shall be used for pump skids, The dimensions l1, and l2 shall be the length and width of the pump skid and l3 shall be the height from the underside of the skid to the top of the highest element of the pump train excluding cabling, piping and auxiliaries such as the barrier/buffer fluid reservoir. Background (K1) and environmental corrections (K2) may be applied. {Total}
- Sound pressure measurements will be taken at each of the microphone positions indicated in ISO 3744 Annexe C as a minimum. The sound pressure measurement at each point will include twenty four 1/3rd octave band measurements (50 to 10,000 Hz) for calculation of the A weighted sound pressure level at that point and the detection of any narrow band noise. {Total}
- Pumps and auxiliary components emitting narrow band noise are to be identified in the proposal and options to eliminate this noise will be presented. Initial detection of narrow band noise will be a subjective determination by the witness during test. If such a subjective detection is made, for the purpose of this specification, narrow band noise shall be considered present if any of the 1/3rd octave band sound pressure levels (dB) exceeds that of both of the 1/3rd octave bands on each side of by 5 dB. Equipment found to emit narrow band noise during the test will not be accepted. {Total}
- The sound power will be calculated per paragraph 8.2.5 for information and compared to that predicted. As far as possible, standard motors with low noise levels shall be used. {Total}
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As far as possible, standard motors with low noise levels shall be used. {Total}
- If noise study report of the plant is available apply indicated value for each equipment (as general rule noise level below 85 db (A) at 1m from the baseplate is acceptable. {TBE Sazeh}
- Maximum sound pressure level at any point 1m from the equipment shall be limited to 85 dBA. {Kermanshah Spec.}
- Sound level tests shall be performed in accordance with IPS-G-SF-900. {Bid Boland Spec.}
3.12 Sound level
Is the A-weighted overall sound-pressure level. {IPS-G-SF-900}
3.13 Sound power
Sound power usually measured in watt, is the amount of energy per unit of time that radiates from a
source. {IPS-G-SF-900}
3.14 Sound power level (Lw)
Sound power level is defined as 10 log (w/w) in Decibels (Db) where W is the sound power in watts and W0 is the reference sound power is equal of 10-12 watt. {IPS-G-SF-900}
The relation of sound power level is as following:
Lw=10 log w/w0
The sound power level cannot be directly measured with an instrument .it is obtained on the basis of the sound pressure level using the following formula :
Lw=Lp+10 Log10 S+ A
Where LP sound pressure level for all spectrum in dB.
S in the surface area of the imaginary envelope on which Lp is measured in m2.
A is noise attenuation due t air absorption ,ground absorption etc. it expressed in dB and for small distance is usually negligible. {IPS-G-SF-900}
3.15 Sound pressure level (LP)
Sound pressure level (LP) is defined as 20 log(p/p) in Db where p is the measured sound pressure in N/m2 and P0 is the reference sound pressure of 2×10-5 N/m2
The relation LP is expressed as :
LP= 20 log (p/p10)
The relation between Lp and Lw for a given octave band is written as follows, according to equation:
LP=Lw-10 Log S- A {IPS-G-SF-900}
Comments:
- For the pump skid, or any individual component, operating at full load, in a free field over a reflecting plane, the sound pressure level measured at any point on a surface 1 meter from the surface of the reference box shall not exceed 85 dBA. No positive tolerance will be allowed. {Total}
- Maximum sound pressure level at any point 1m from the equipment shall be limited to 85 dBA. {Kermanshah Spec.}