How to test industrial equipment for noise levels?

[motorambler]

I have taken various readings at 7m and 11m of a particular genset but don't know if I should be using the A scale or C scale or something else. Is there a standard or "proper" way to measure the noise emitted from industrial machinery?

Lets say you have a Radio Shack noise level meter and want to measure the noise generated by a piece of equipment -- a diesel generator set in this case. If the ambient surrounding noise (i.e., the generator set is not running) is 58dB, and then is measured at 69dB when the generator is running, does that mean that the generator's noise level is 69dB, or is there a formula to use to factor the 58dB ambient noise? Would the genset still read 69dB if the ambient noise was 65dB instead of 58dB?

Any tips/thoughts on how to properly test our equipment would be greatly appreciated. No, we do not have access to a special enclosed facility to do this testing -- we'll have to make do with the open yard at our facility.

 

[IRstuff]

Perhaps you should do some research first:

http://en.wikipedia.org/wiki/Decibel

TTFN
faq731-376

 

[sunnysky]

From my test experience, I have always relied on calibrated equipment from Brüel & Kjær using calibrated distances vs loss for corrections.