Daikin Noise Levels, Please Help

[gwilliamson]

Hi Chaps
Really need some help if possible. I have an installation of two 10 kw wall mounted Daikin Units in a classroom. In the book they are rated at 45Db High at 1 metre. The design consultant has just phoned me today and stated the maximum limit for any equipment in a classroom is NR30 or 39DB at 3 metres. I spoke to Daikin this afternoon to ask what the sound levels are likely to be at 3 metres and their advice was to use a sound meter after the install..Very helpful!!
Is there a definate way or calculation to work out the information i require?
Any help on this a big thankyou as have to phone the consultant tomorrow morning.
Thanks
Gareth.

[Andy]

Hi Chaps
Really need some help if possible. I have an installation of two 10 kw wall mounted Daikin Units in a classroom. In the book they are rated at 45Db High at 1 metre. The design consultant has just phoned me today and stated the maximum limit for any equipment in a classroom is NR30 or 39DB at 3 metres. I spoke to Daikin this afternoon to ask what the sound levels are likely to be at 3 metres and their advice was to use a sound meter after the install..Very helpful!!
Is there a definate way or calculation to work out the information i require?
Any help on this a big thankyou as have to phone the consultant tomorrow morning.
Thanks
Gareth.

Hi Gareth

I have a spreadsheet that was given to me by a friend in another company. If I put in 45dba at 1m it gives me 35.5dba at 3m

http://www.engineeringtoolbox.com

will give you the formula if you need it and probably a program to work it out.

hope this helps.
Kind Regards Andy

[momo]

Double distance: lose 6dB in open space therefore 39dB at 2m... however absorbtion and reflection in interiors must be taken into account:... at 3m I guess you should be ok for the required spec. A fan produces a whoosh similar to white noise, however motor noises are different and vibrations can resonate. Borrow a decent dB meter and check discreetly!

[Jez]

Remember that there are two of the units, so you will need to add 3dB. The manufacturers data will be at anechoic conditions, so real sound will invariably be higher.

[gwilliamson]

Many thanks Chaps for all your help.