radiator noise presentation - enoisecontrol · radiator noise control summary • use acoustical...
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Mark E. Schaffer, P.E.
Schaffer Acoustics Inc.Pacific Palisades, CA
Genset Radiator Noise
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Sample Municipal Code Limits
75 dBA75 dBAIndustrial
60 dBA65 dBACommercial
45 dBA55 dBAResidential
NighttimeDaytimeLand Use
Codes usually require compliance during testing,but not during emergency operation
ASHRAE TC 2.6
Skid-Mounted Radiator
ASHRAE TC 2.6
1500 KW GensetMechanical Noise
60
70
80
90
100
110
63 125 250 500 1000 2000 4000 8000
Octave Band Center Frequency in Hertz
L P @
15
met
ers
in d
B
Without Radiator, 89 dBA
With Radiator, 92 dBA
ASHRAE TC 2.6
Acoustical Louver
Length4” – 12 “
Insertion Loss3 – 10 dBA
Pressure Drop∼0.25” w.g.@ 500 FPM
ASHRAE TC 2.6
Lined Duct Transition
Length30” – 120“
Insertion Loss1 to 5 dBA
Pressure Drop0.0” w.g.
ASHRAE TC 2.6
Sound Traps
Length30” – 120“
Insertion Loss10 to 40 dBA
Pressure Drop0.05” to 0.30” w.g.
@ 500 FPM
ASHRAE TC 2.6
Typical Low Noise1.5 MW Genset Installation
118,000 CFM
GeneratorRad
10’ long, 236 ft2 face area
Intake AirSoundTraps
Disch.Air
SoundTraps
ASHRAE TC 2.6
Low Noise Genset Installationwith Remote Radiator
40,000 CFM
Generator
10’ long,80 ft2 face area
IntakeAir
SoundTraps
Disch.Air
SoundTraps
Exh.Fan
ASHRAE TC 2.6
Vertical CoreRemoteRadiator
Note narrowfan blades
ASHRAE TC 2.6
Horizontal CoreRemote Radiator
ASHRAE TC 2.6
Remote Radiator Installation
ASHRAE TC 2.6
RemoteRadiator
Air InletView
Note widefan blades
ASHRAE TC 2.6
Radiator Noise Levels
30
40
50
60
70
80
90
100
110
63 125 250 500 1000 2000 4000 8000
Octave Band Center Frequency in Hertz
L P @
15
met
ers
in d
B 84” Skid-mounted
64” Remote
81” Remote93” Remote
ASHRAE TC 2.6
Fan Noise Level vs RPM
-20
-15
-10
-5
0
100 95 90 85 80 75 70 65 60 55 50
% of Full RPM
Rel
ativ
e Le
vel i
n d
B
ASHRAE TC 2.6
Differential Costs ofRemote Radiator for 1500 KW
($25,000)($25,000)Radiator
$20,000$5000Room Ventilation
$62,000+$99,400Total
$10,000+---Radiator Piping
$32,000$94,400Sound traps
RemoteRadiator
Skid-MountedRadiator
ASHRAE TC 2.6
Remote Radiator Benefits
• Smaller ventilation opening(1/2 to 2/3 smaller)
• Fewer or shorter sound traps(1/2 to 2/3 reduction)
• More space in generator room
• Option to select quiet radiator
• Option to locate radiator for lowest noiseexposure to noise-sensitive areas
ASHRAE TC 2.6
Radiator Noise Control Summary
• Use acoustical louvers or sound traps for a skid-mounted radiator, if space is available.
• Consider remote radiator if space precludessound traps for skid-mounted radiator.
• Consider several remote radiator fan selections,weighing cost, location and size.
• Consider VFD fan motor for lower speed &lower noise during cooler nighttime ambient airconditions.
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ASHRAE TC 2.6