radiator noise presentation - enoisecontrol · radiator noise control summary • use acoustical...

Mark E. Schaffer, P.E.

Schaffer Acoustics Inc.Pacific Palisades, CA

mark@schaffer-acoustics.com

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