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62 TRG-TRC007-EN
notes
period four
Equipment Sound Rating
Depending on the type of equipment, sound ratings for HVAC equipment are
typically given as sound-power levels by octave band or as a single dBA rating.
Outdoor equipment, such as an air-cooled chiller or condensing unit, may be
rated in terms of A-weighted sound-pressure level (dBA) at a specific distance
from the equipment. This generally assumes a free-field environment and may
be useful for comparing equipment from various manufacturers. Nevertheless,
the sound-pressure level by octave band should still be available from the
manufacturer for use in an acoustical analysis.
As mentioned, air-handling equipment is typically rated in terms of sound-
power level per octave band. Typically, this data is given for the octave bands
from 63 Hz through 8,000 Hz. The availability of accurate, tested sound data for
HVAC equipment is vitally important to any acoustical analysis.
Sound Power by Octave Band
octave
band
1
2
3
4
5
6
7
8
octave
band
1
2
3
4
5
6
7
8
center
frequency (Hz)
63
125
250
500
1,000
2,000
4,000
8,000
center
frequency (Hz)
63
125
250
500
1,000
2,000
4,000
8,000
equipment
sound power
(dB ref 10
-12
W)
103
104
100
101
98
93
88
85
equipment
sound power
(dB ref 10
-12
W)
103
104
100
101
98
93
88
85
Figure 67