16
K 2 . 1
Hz
63
Lw(dB)
125
Lw(dB)
250
Lw(dB)
500
Lw(dB)
1000
Lw(dB)
2000
Lw(dB)
4000
Lw(dB)
8000
Lw(dB)
LwA
(dBA)
Supply air
8
8
4
-2
-13
-12
-23
-30
Extract air
10
10
5
-8
-15
-16
-28
-32
Radiated 1
-12
-7
-8
-19
-30
-29
-33
-32
-15
Radiated 2
-5
-6
-13
-24
-32
-29
-39
-33
-17
Explanation of diagram:
6RXQGGDWDLVVSHFLȴHGDVVRXQGSRZHUOHYHO/Z$LQWKH
capacity diagrams. (This is sound to duct.)
These values can be corrected by means of the table for
WKHGLHUHQWRFWDYHEDQGVLQRUGHUWRORRNDW/ZZLWKRXW
adaptation to A band).
The correction table for the various octaves is stated in
Lw, which means that the Lw values are after conversion
of each octave for supply air and extract air.
Radiated sound from the unit must be calculated from
the supply air diagram.
Radiated 1: K2 free hanging
Radiated 2: K2 built-in kitchen
:RUNLQJSRLQWP
KDJDLQVW3D
7.3. CORRECTION FACTOR FOR LW
Data for supply air is measured in accordance with
Ζ62bWKHȊΖQGXFWPHWKRGȋ
Radiated noise is measured in accordance with ISO
9614-2. Bruel & Kjær measuring equipment, type 2260.
>
EXAMPLE 3
Radiated sound in total from
the unit in LwA
At the bottom right of the table, a total
value for radiated sound from the unit
is stated in LwA. This is an aggregate
value.
The values for the radiated sound
IRUWKHGLHUHQWRFWDYHVKDYHEHHQ
totalled up and then corrected for
$bEDQG
This is used as follows:
The LwA value is read from the supply
air capacity diagram, in our example
60 dBA, and this is then subtracted
from the total value (this is also an
LwA value).
LwA 60 dBA - 15 dBA = 45 dBA, (which
is then stated in LwA, the sound
power level adapted to the ear’s A
band).
>
EXAMPLE 2
Radiated sound in Lw per octave
If a reading of 60 dBA at the working
point is taken from the supply air
capacity diagram (which indicates
sound to duct) in order to arrive at a
subsequent Lw value for the various
octaves, a deduction is then made
from the value for the relevant octave
for the row with radiated sound.
60 dBA - 19 (for 500Hz) = 41 dB, which
is an Lw value and indicates the
radiated sound from the unit in this
octave.
>
EXAMPLE 1
Sound to duct in the various
octaves is stated in Lw
The working point gives 60 dBA from
the capacity diagram for supply
air. I am interested in what this is
VSHFLȴFDOO\LQWKH+]UDQJH
60 dBA - 4 = 56 dB which is an Lw
value (sound power level without
adaptation to the ear’s A band)