ClimateMaster Engineering Sound Lab By Wes Wostal.
-
Upload
steven-cox -
Category
Documents
-
view
232 -
download
1
Transcript of ClimateMaster Engineering Sound Lab By Wes Wostal.
ClimateMaster Engineering Sound Lab
By Wes Wostal
How The New Sound Lab Evolved
• Importance of sound • Great products... No real way to design for
sound• Easy justification
Design Goals
• Must be in house• Test capability to 50 & 60 Hz• Construction of reverberant room• Construction of “ducted discharge” room• National Instruments LabVIEW• ISO 3741• NAVLAP certified• Capable of taking us into the future
In House Lab
• Outside sound testing is expensive• Outside testing offers little to no design
change opportunity
Test Capability Down to 50 & 60 Hz
• Wave length: λ = c/f
• Wave length at 60 Hz = 18.8 ft• Wave length at 125 Hz = 9.0 ft
• ClimateMaster sound lab internal dimensions: 31’L x 24’ W x 19’ T
• c (air) = 1128 ft/sec • f = frequency (Hz)
Reverberant Room Size Requirements Chamber Volume by ISO 3741
Lowest 1/3 octave bandfrequency of interest Hz
Minimum volume of thetest room m³
100 Hz 200 m³
125 Hz 150 m³
160 Hz 100 m³
200 Hz and higher 70 m³
ClimateMaster Reverberant Room Volume
400 m³
=
14136 ft³
Construction Reverberant Room
• Isolated slab• 4” thick inner steel walls• 8” thick outer sand filled concrete block wall• 1’ wide air gap• 2’ effective wall thickness• Sound attenuators for return and supply air
Construction “Ducted Discharge” Room
• 4” thick perforated steel walls • Single sound attenuator for return and supply
Air
National Instruments LabVIEW
• Great history with LabVIEW• LabVIEW for sound data measurement• LabVIEW for room conditioning• 25 tons of air side conditioning• 30 tons of water side conditioning• 10,000 CFM variable frequency drive air handler• 36” double walled duct
ISO 3741
• Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for reverberation rooms
• Specifies room requirements, source location, general rules for operating conditions, instrumentation and techniques for obtaining sound pressure levels from which sound power levels are calculated with grade 1 accuracy
NAVLAP Certified
• National Voluntary Laboratory Accreditation Program
• Administered through NIST
Capable Of Taking Us Into The Future
• ClimateMaster products quieter by design• Interior sound levels < NC20
From ClimateMaster to Customer
• Sound testing as part of development• ARI 260 and 350 standards• Product sound data• NC• ClimateMaster Sound Analyzer
ARI 260
Sound Rating of Ducted Air Moving and Conditioning Equipment
Adopted in 2000
Revised in 2001
What is ARI 260?
• Sound rating standard for ducted air moving and conditioning equipment
• Establishes a method of sound rating indoor a/c equipment
• Covers air source-ARI 240, & 340; water source-ISO 13256; fan Coil-ARI 440; central station ARI 430
• Provides for standard published data
Why ARI 260?
• Previously no valid sound rating standard for wshp’s
• Every manufacturer used different testing procedure
• Sound rating comparisons between manufacturers were impossible
Important Definitions• Sound Power: W [watt], is a fundamental
property of a sound source, the amount of acoustic energy radiated into the environment. denoted by ‘Lw’
• Sound Pressure: is the expression of the acoustic power in the environment. denoted by ‘Lp’
• Reference Sound Source: A portable, aerodynamic sound source that produces a known stable broad band sound power output.
Sound Power Vs Pressure
Definitions Continued• Comparison Method: A method of determining sound
power level of a source under test in a reverberation room by comparing the average sound pressure level of that source to the average sound pressure level of a reference sound source of know sound power level output. the difference in sound power level is equal to the difference in sound pressure level when the conditions in the room are the same for both sets of measurements.
Definitions Continued
• Frequency or Hz - Cycles per second• Frequency Spectrum - Audible range of
frequency 20 - 20000 Hz for humans• dB - Decibel unit of measure expressing a log
ratio of two quantities. 3-5dB barely perceptible. 10dB is perceived as twice as loud
Definitions Continued
• Octave Band: a band of sound covering a range of frequencies such that the highest is twice the lowest. octave band frequencies are: 63; 125; 250; 500; 1000; 2000; 4000; and 8000
• 1/3 Octave Band: A band of sound covering a range of frequencies such that the highest frequency is the cube root of two times the lowest. 1/3 octave band frequencies for the 125 Hz octave band are: 100; 125; and 160.
What is Sound
• A disturbance that propagates in an elastic medium (air)
• Created by a transference of mechanical energy to the medium
• Generally associated with the auditory sensation created by the disturbance in the medium
What is Noise?
• Unwanted Sound: A waste byproduct of mechanical, electrical, and fluid processes
• Noise consists of energy at frequencies that are representative of the mechanical processes that create the sound
Frequency Spectrum
Vibration
Fan, Comp and Pump Noise
Terminal Boxes
Transformer and Ballasts
Recip and Centrif Chillers
Damper Noise
Diffuser Noise
16 32 63 125 250 500 1k 2k 4k 8k 16k
Octave Band Center Frequency
Throb Rumble Roar Whistle Hiss
Typical Sound Pressure LevelsSound Source
Sound Pressure Level
Subjective Reaction
Military jet takeoff at 100 ft 140 Extreme danger
Artillery fire at 10 ft 130Passenger jet takeoff at 100 ft 120 Threshold of pain
Loud rock concert 110 Threshold of comfort
Subway Station platform 100Unmuffled large diesel engine 90 Very loud
Computer printer room 80Freight train at 100 ft 70Conversational speech at 3 ft 60Window air conditioner 50 Moderate
Quiet residential area 40Whispered conversation 30Buzzing insect at 3 ft 20Threshold of hearing 10 Faint
Threshold of youthful hearing 0 Threshold of hearing
Why is Measuring Sound So Difficult?• Measuring sound is more difficult than pressure or
temperature• Requires detailed analysis of distinct frequencies• Human ears sense sound from 20Hz-20KHz• ClimateMaster Sound Analyzer accommodates a
wide range 50Hz-11KHz• More than 10,000 data points to analyze per test
• We have the solution!!
Product Sound Data
• Product Sound Test Method– Set room conditions– Run ambient / background test– Run RSS (reference sound source)– Run test unit
Product Sound Data
• Sound Data Collected– Sound pressure of ambient – Sound pressure of RSS– Sound pressure (Lp) of unit
Product Sound Data
• 1/3 octave sound power calculations
– Sound power: Lw = Lp + (Lwp - Lpr)• Lp = Sound pressure of unit• Lwp = Sound power of the RSS• Lpr = Sound pressure of the RSS
Product Sound Data
• 1/1 octave sound power calculations• Example 100Hz, 125Hz, and 160Hz
– Lwo = 10log10[Σ10(Lw(n)/10)]• Lwo = 125Hz octave band sound power• Lw(n) = sound power of each 1/3 octave
• Lwo = 1/1 octave sound power = published data
A & C Weighted Sound Power Level
• A Weighted Sound Power Level– Range of 700 - 4000 Hz– Noise in occupational environment– Best with sources of similar range
• C Weighted Sound Power Level– Range of 50 - 5kHz– Wide range noise in occupational environment– Best with sources of wide range like music etc.
1/1 Octave Hz A-Weight Adder
63 -26.2
125 -16.1
250 -8.6
500 -3.2
1000 0
2000 1.2
4000 1.0
8000 -1.1
ARI 260 Test Setup Options
• Ducted discharge• Ducted inlet• Free inlet and casing radiated• Casing radiated• Free inlet
Ducted Discharge
Ducted Inlet
Free Inlet & Casing Radiated
Casing Radiated
Free Inlet
GRH/V 030 ARI 260 Free Inlet & Case Radiated Data
OCTAVE BAND FREQUENCY, Hz
MODE 125 250 500 1000 2000 4000 8000FAN ONLY: LOW SPEED 70 62 58 56 53 50 40
FAN ONLY: HIGH SPEED 75 65 59 59 56 54 46COOLING: LOW SPEED 72 63 58 56 54 49 41COOLING: HIGH SPEED 73 65 59 58 56 53 46HEATING: LOW SPEED 74 64 59 56 54 49 42HEATING: HIGH SPEED 76 67 60 59 56 53 47
GRH/V 030 ARI 260 Ducted Discharge Data
OCTAVE BAND FREQUENCY, Hz
MODE 125 250 500 1000 2000 4000 8000
FAN ONLY: LOW SPEED 77 65 68 64 62 62 57
FAN ONLY: HIGH SPEED 72 68 69 69 66 65 61
COOLING: LOW SPEED 82 65 68 65 63 63 57
COOLING: HIGH SPEED 80 66 68 66 64 63 58
HEATING: LOW SPEED 84 67 69 65 63 62 58
HEATING: HIGH SPEED 83 67 69 67 64 63 59
NC (Noise Criterion Curves)
• Provide a coloration curve of response that represents the ear’s sensitivity to sound
• Curve range is 63 - 8000 Hz and on an octave band sound pressure scale
• Often used in building design• Source sound pressure level measured at
each octave band must be below the specified NC curve to meet NC rating
Typical NC
Curves
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
63 125 250 500 1000 2000 4000 8000
OCTAVE BAND FREQUENCY, Hz
PW
L,
OC
TAV
E S
OU
ND
PO
WE
R B
AN
D S
OU
ND
LE
VE
L,
dB
re
10
-12
W
att
s
NC 70
NC 60
NC 50
NC 40
NC 30
NC 20
Unit NC Rating
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
63 125 250 500 1000 2000 4000 8000
OCTAVE BAND FREQUENCY, Hz
PW
L,
OC
TAV
E S
OU
ND
PO
WE
R B
AN
D S
OU
ND
LE
VE
L,
dB
re
10
-12
W
att
s
NC 70
NC 60
NC 50
NC 40
NC 30
NC 20
NC50
ClimateMaster Sound Analyzer
Inputs Req
STEP 1 Determine Room VolumeLength 15 ft
Width 15 ft
Height 10 ft
Room Vol 2250 ft3
STEP 2 Determine distance of the occupant from the ceilingD 6 ft
STEP 3 Determine Room/Ceiling Attenuation (CAT)
63 125 250 500 1000 2000 4000
CAT (dB) 13 16 15 17 17 18 19
STEP 4 Determine Octave band sound power from Climatemaster data Model
Test type
125 250 500 1000 2000 4000SPL (dB) 63 59 57 59 55 45
STEP 4 Calculate Sound Pressure
125 250 500 1000 2000 4000
SPL (dB) 41.17 37.26 32.36 33.46 27.55 15.65
STEP 5 Verify NC acceptable Levels
Octave Band Frequency, Hz
GRH006
Octave Band Frequency, Hz
Choose Ceiling Type
Octave Band Frequency, Hz
NC CURVE
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
63 125 250 500 1000 2000 4000 8000
OCTAVE BAND FREQUENCY, Hz
PW
L, O
CT
AV
E S
OU
ND
PO
WE
R B
AN
D S
OU
ND
LE
VE
L, d
B r
e 1
0-1
2 W
att
s
SP
L, O
CT
AV
E B
AN
D S
OU
ND
PR
ES
SU
RE
lE
VE
L, d
B r
e .0002 M
ICR
OB
AR
NC 15 NC 20 NC 25 NC 30 NC 35
NC 40 NC 45 NC 50 NC 55 NC 60
NC 65 NC 70 Simulated
NC 70
NC-60
NC 50
NC 40
NC30
NC 20
Glass Fiber 0.1 lb/ ft2 Density 5/8 in Thick
Ducted Discharge
NC 15 NC 25 NC 35 NC 45 NC 55 NC 65 NC 75+
Very Quiet Moderate Very Noisy Extremely Noisy
-ve values may be assumed as 0
Important Notes
• 63 Hz is difficult to test• 125 Hz is most problematic octave
About Comparison
• Must be ‘apples to apples’-Look for ARI 260 conformance
• Look for weighting ‘A’ versus ‘C’• No ARI 260... No comparison
Things to Remember• Sound power is pure source energy• Sound pressure is source with room affects• Sound power can be used to predict sound
pressure in a specified room• ARI 260 and 350 are THE ONLY sound
rating standards• Comparisons valid using ARI 260 only• Use the ClimateMaster Sound Analyzer
Thank You