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Considerations
Q Fan Sound Data
Trane Q fans are designed to be used in
any installation where a standard airfoil
centrifugal fan can be used. The sound
level of the Q fan in the difficult to
attenuate lower frequencies is lower
than that produced by standard airfoil
centrifugal fans with the same capacity.
Sound levels in the higher octave
bands compare favorably. Therefore,
the Q fan will provide quieter sound
levels in a typical installation.
Designing the system for lower static
pressures and selecting the fan at high
efficiency will result in quieter fan
operation, as well as power savings.
The best method of acoustical design
makes use of unit sound power levels
in all eight octave bands. These sound
power levels for each Trane Q fan can
be obtained from the Trane
computerized fan selection program.
In the past, it has been an industry
practice to test air moving devices
within a reverberating room to
determine total sound power. This has
presented the problem of
distinguishing between inlet and
discharge sound power ratings, where
significant differences do exist.
Trane engineers solved this problem by
locating the fan adjacent to the
reverberating room and ducting to it.
By turning the fan around, inlet and
discharge sound power can be
measured separately and accurately.
By ducting both the inlet and outlet,
radiated shell sound power was
determined. Using this method with
the Trane reverberant room that
conforms to ASHRAE standards,
acoustical data on the Q fan is
substantially more accurate than fan
ratings made using conventional
techniques. Tests covered all sizes and
speeds over the entire performance
range of the line. A computer program
was then used to determine the precise
relationship of speed, size, point of
operation and frequency.
Plus silencer attenuation is shown in
Tables S-1 and S-2. Use the Trane fan
selection program to obtain precise
Plus attenuation with regenerated
noise included.
Trane ASA10B Sound Analyzer
Trane offers a low cost 10 octave
band sound analyzer for sound
measurements. Capable of measuring
noise from 30 to 123 db sound
pressure with flat, dbA and dbC sound
LCb weightings this rugged meter
permits comparative and absolute
sound measurements to be taken.
Ideas On How To Use The ASA10B
The ASA10B can be used on existing
jobs to measure equipment sound
levels by octave bands. Compare this
data with NC charts to determine what
frequencies need to be attenuated and
by how much. The type and cost of
noise control options is a function of
the problem
frequency and amplitude.
On acoustical retrofits, the ASA10B can
accurately compare before and after
noise levels. Real measurements
establish the benefit of the retrofit.
Trane Acoustics Program
Trane has a system level acoustics
computer program that accurately
converts fan sound power to room NC
levels. This program uses ASHRAE
approved algorithms and is the most
complete and accurate sound predictive
program in the HVAC industry. Use of
the Trane acoustics program allows all
sound paths to be checked and
attenuated to achieve the desired room
sound levels without costly
overdesigning. Contact your Trane sales
engineer for more details on this
Customer Direct Service (C.D.S.)
Network program.
Q Fan/Super Q II Plus Silencers
Trane has a unique silencer for the
Q fan. This low turbulence, high
attenuation silencer dramatically
reduces airborne noise from the Q-Fan.
A bulleted cylindrical silencer attenuates
medium and high frequency noise
generated by the Q Fan to a point where
the Q Fan can be successfully installed
in such sound sensitive applications as
ceiling plenums successfully.
Trane’s Plus silencer has a field
repositionable bullet (center body) that
can be relocated close to the Q Fan
outlet. This unique feature eliminates
low frequency turbulence and makes
the Q fan quieter than plug fans or other
axial or mixed flow fans. Pressure drop
through the Plus silencer is
approximately .1-inch sp. The Plus
silencer has been used on many
projects in the last five years to
consistently create NC 15-35 spaces.
Table A-5 — Inlet Vane Sound Data
DB Addition For Vane Position Indicated
Octave Mid- Wide 75% 50% 25%
Band Frequency Open W/Open W/Open W/Open
1 63 +4 +8 +12 +14
2 125 +8 +9 +9 +10
3 200 +7 +8 +9 +9
4 500 +4 +5 +6 +6
5 1,000 0 0 0 0
6 2,000 0 0 0 0
7 4,000 0 0 0 0
8 8,000 0 0 0 0