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Posted By stretton1977
This is my first post, I have often browsed on this forum and have now come across a tricky question that has gone way over my head, just wonder if anybody on here is a buff when it comes to noise?.
Basically, I am doing a study on a proposed sewage treatment plant and I need to work out the total sound power level of this plant.
Obviously I have all the relevant details on all the individual plant machinery and equipment that this plant will produce, however I cant seem to put it all into this tiny space!.
I really just thought I would test the water first to see if anybody could give me a bit of advice, I could send any further information needed by email if needed?.
Thanks for any help or advice in advance
Regards
Gary
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Posted By Andrew Kelleher
Gary
I have recently arranged for a occupational noise assessment with an organisation called EEF. If you require details of the service that they offer, please email me at apk124@live.co.uk.
Andy
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Posted By Phil Rose
I am not sure if your query is about occupational or environmental exposure. If the latter I suggest a chat with an EHO at the local council may help. Either way I would suggest that whatever the reason for trying to assess the overall level prior to installation, any figure that you are likely to arrive at is going to be 'indicative' only.
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Posted By D. Hilton
Gary
If you want to send more information, I may be able to point you in the right direction
regards
Darren
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Posted By stretton1977
Cheers Darren,
If you could send me your email to me that would make it easier to send you the information.
My address is gary.stretton@yahoo,com
Cheers
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Posted By D. Hilton
Hi Garry,
You will need to calculate the sound pressure level at your own point of interest from each noise source i.e a point on the boundary.
Equipment positioned at or near the ground the SPL will be calculated as unidirectional hemispherical propagated sound,whereas the SPL above ground or at a height will be calculated as unidirectional spherical propagated sound.
unidirectional spherical propogated sound:
SPL = SWL - 20 Log r - 11
SPL = Sound Presure Level dB
R= distance in metres of recieving point from the source
SWL Sound Power Level dB
unidirectional hemispherical propogated sound:
SPL = SWL - 20 Log r - 8
SPL = Sound Presure Level dB
R= distance in metres of recieving point from the source
SWL Sound Power Level dB
i.e.
A fan located at a rooftop has a SWL of 90 dB, the sound Pressure Level at 20 metres would be
90-20 Log (20)- 11 = 53 dB
If the same equipment was located at the ground level
the SPL would be calculated as
90-20 Log(20) - 8 = 56 dB
Assume you have calculated the SPL for three items of equipment
SPL 1 = 55 dB
SPL 2 = 70 dB
SPL 3 = 77 dB
The total Sound Pressure Level is calculated as
10 Log (10^55/10)+ (10^70/10) + (10^77/10)
= 78 dB
Regards
Darren
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Posted By D. Hilton
in answer to a number of emails the following may provide further explanation
regards
(SPL) ( 55 dB ) ( 70dB) (77 dB)
(SPL)/10 (5.5 ) (7 ) ( 7.7)
10(SPL)/10(3162778) (10000000) (50118723)
S 10(SPL)/10(3162778 + 10000000 + 50118723) = 60434951
Log 10S 10(SPL)/10(Log 10 60434951 = 7.781288)
10 Log 10S 10(SPL)/10 (77.81) or (78 dB)
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Posted By Paul Leadbetter
I think it has lost something in the translation!
Paul
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Posted By D. Hilton
Unfortunately you cant put tables or cut and paste into the response box,
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