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Existing Data
Manufacturers supplied EPA (Contractor BBN) with noise data at 7
meters for 194 compressor models. Table 7-5 lists the data in terms of
compressor capacity, engine type, and standard/quieted units. Also shown
in the table is the number and percent of units below a particular noise
level.
In summary, the data shows:
• Standard models of gas engine powered compressors range in noise
level from 71. 0 to 92. 0 dBA with a mean value of 82. 8 dBA.
• Silenced models of gas engine powered compressors range in noise
level from 72 to 81 dBA with a mean value of 76.1 dBA.
• Standard models of diesel engine powered compressors of less than
501 cfm capacity, range in noise level from 79. 5 to 93.4 dBA with
a mean value of 86.1 dBA.
• Silenced models of diesel engine powered compressors, of less
than 501 cfm capacity, range in noise from 70.0 to 88.0 dBA with
a mean value of 76.4 dBA.
• Standard models of diesel engine powered compressors, of greater
than 500 cfm capacity, range in noise level from 86. 8 to 101.8 dBA
with a mean value of 92, 8 dBA.
• Silenced models of diesel engine powered compressors of greater
than 500 cfm capacity, range in noise level from 73. 0 to 82. 0 dBA
with a mean value of 78. 7 dBA.
7-10
-------
Table 7-5 (a)
PERCENT AND NUMBER OF PORTABLE AIR COMPRESSORS
WITH NOISE LEVELS NOT IN EXCESS OF A PARTICULAR VALUE*
(Major Category of Portable Air Compressors by Capacity and Type of Engine)
Gasoline Engine, All Capacities**
Standard Models
dBA Level
71.0
72.0
73.0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
81.0
82.0
83.0
84.0
85.0
86.0
87.0
88.0
89.0
90.0
91.0
92.0
Percent of
Cumulative
Units Below
0.0
3.12
3. 12
9.37
9.37
12.50
12.50
18.75
18.75
21.87
28. 12
28. 12
34.37
50.00
62.50
75.00
81.25
90.26
90. 62
93.75
96.87
100.00
Number of
Units Below
0
1
1
3
3
4
4
6
6
7
9
9
11
16
20
24
26
29
29
30
31
32
Quieted Models
dBA Level
72.0
73.0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
81.0
Percent of
Cumulative
Units Below
0.0
11.54
15.38
26.92
50.00
65.38
69.23
84.62
92.31
100.00
Number of
Units Below
0
3
4
7
13
17
18
22
24
26
Mean: 82. 8 dBA***
Standard Deviation: 4. 92 dBA***
Mean: 76.1 dBA***
Standard Deviation: 2.40 dBA***
Average sound pressure level in dBA at 7m according to the recommended
measurement practice of ISO 2151-1972. Manufacturers were sometimes
imprecise in defining the noise data submitted to BBN. BBN has treated this
data as an average of noise level for a model based on testing a number of
units.
BBN did not document in its report the manufacturers whose model data is
included in the 194 data points reported.
*** The mean is a simple average of model noise data. Data is not available to
weight by relative model unit volume sold. Partial weighting schemes by
capacity and/or manufacturer were not utilized.
**
7-11
-------
Table 7-5(b)
PERCENT AND NUMBER OF PORTABLE AIR COMPRESSORS
WITH NOISE LEVELS NOT IN EXCESS OF A PARTICULAR VALUE*
(Major Category of Portable Air Compressors by Capacity and Type of Engine)
Diesel Engine, Below 501 cfm Capacity**
Standard Models
dBA Level
79.5
80.5
81.5
82.5
83.5
84.5
85.5
86.5
87.5
88.5
89. 5
90.5
91.5
92. 5
93. 5
Percent of
Cumulative
Units Below
0.0
2.22
2.22
17.78
24.44
31.11
48.89
62.22
71. 11
73.33
77.78
86.67
88.89
97.78
100.00
Number of
Units Below
0
1
1
8
11
14
22
28
32
33
35
39
40
44
45
Quieted Models
dBA Level
70.0
71.0
72.0
73.0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
81.0
82.0
83.0
84.0
85.0
86.0
87.0
88.0
Percent of
Cumulative
Units Below
0.0
11.43
11.43
14.29
17.14
22.86
57. 14
68.57
71.43
77. 14
77.14
82.86
88.57
88.57
97.14
97.14
97.14
97.14
100.00
Number of
Units Below
0
4
4
5
6
8
20
24
25
27
27
29
31
31
34
34
34
34
35
Mean: 86.1 dBA***
Standard Deviation: 3.35 dBA***
Mean: 76.4 dBA***
Standard Deviation: 4.07 dBA***
Average sound pressure level in dBA at 7m according to the recommended
measurement practice of ISO 2151-1972. Manufacturers were sometimes
imprecise in defining the noise data submitted to BBN. BBN has treated this
data as an average of noise level for a model based on testing a number of
units.
BBN did not document in its report the manufacturers whose model data, is
included in the 194 data points reported.
*** The mean is a simple average of model noise data. Data is not available to
weight by relative model unit volume sold. Partial weighting schemes by
capacity and/or manufacturer were not utilized.
**
7-12
-------
Table 7-5{c)
PERCENT AND NUMBER OF PORTABLE AIR COMPRESSORS
WITH NOISE LEVELS NOT IN EXCESS OF A PARTICULAR VALUE*
(Major Category of Portable Air Compressors by Capacity and Type of Engine)
Diesel Engine, Above 500 cftn Capacity'!
Standard Models
dBA Level
86.8
87.8
88.8
89.8
90.8
91.8
92.8
93.8
94.8
95.8
96.8
97.8
98.8
99.8
100.8
101.8
Percent of
Cumulative
Units Below
0.0
6.25
15.62
28. 12
37.50
46.87
53. 12
65.62
68.75
68.75
75.00
84.37
87.50
93.75
96.87
100.00
Number of
Units Below
0
2
5
9
12
15
17
21
22
22
24
27
28
30
31
32
Quieted Models
dBA Level
73. -0
74.0
75.0
76.0
77.0
78.0
79.0
80.0
81.0
82.0
83.0
84.0
85.0
86.0
87.0
Percent of
Cumulative
Units Below
0.0
4. 17
8.33
16.67
45.83
58.33
62.50
66.67
70.83
75.00
79. 17
79.17
87.50
91.67
100.00
.Number of
Units Below
0
1
2
4
11
14
15
16
17
18
19
19
21
22
24
Mean: 92. 8 dBA***
Standard Deviation: 4. 08
Mean: 78.7
Standard Deviation:
3. 90 dBA***
Average sound pressure level in dBA at 7m according to the recommended
measurement practice of ISO 2151-1972. Manufacturers were sometimes
imprecise in defining the noise data submitted to BBN. BBN has treated this
data as an average of noise level for a model based on testing a number of
units.
BBN did not document in its report the manufacturers whose model data is
included in the 194 data points reported.
*** The mean is a simple average of model noise data. Data is not available to
weight by relative model unit volume sold. Partial weighting schemes by
capacity and/or manufacturer were not utilized.
**
7-13
-------
REPEATABILITY OF DATA
Data acquired using the CAGI/PNEUROP method were compared with
available manufacturer's data. Figure 7-3 present a histogram of the com-
pressor in which good repeatability is shown, i. e., both mean and median
ratios are approximately zero. Further comparisons are made in Table
7-8, in which noise levels associated with four models of the same com-
pressor are presented. As shown by the data, noise levels repeat to within
1.5 dB at individual measurement positions and to within 1.0 dB on the
average.
7-14
-------
ai
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Median: 0 dB A
Mean: - 0.1 dB A
a=1.5dB A
I I
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Sound Level Difference, dB A
(Mfgr. Minus Survey)
NOTE: Silenced Models Only
Figure 7-3. Comparison of Manufacturer Supplied with Survey Data
7-15
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NOISE DIRECTIVITY
Noise levels measured during compressor operation at rated power were
analyzed to assess noise directivity around portable air compressors. Table
7-6 lists dBA levels, average dBA levels, and the maximum directivity factor
associated with the six types of compressors. The data were acquired using
the 10-point hemisphere measurement method. The data show little variance
in noise level from position to position, indicating little directivity of noise.
Figure 7-4 show a polar plot of noise at various azimuthal locations,
every 30 degrees in the horizontal plane, around a compressor. Again, little-
directivity is shown.
7-17
-------
Table 7-7
AIR COMPRESSOR NOISE DIRECTIVITY
Microphone
Location*
A
B
C
D
E
F
G
H
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Average dBA
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77
77
77
77
78
77
78
77
77
76
77.1
Maximum Directivity
Factor ** 1.23
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Sound Level, dBA
71
75
72
72
72
71
71
72
71
70
71.7
2.14
72
72
73
73
71
71
72.5
72.5
72
72.5
72.2
1.22
92
94.5
93
94.5
94.5
93
91
91.5
92
89
92.5
1.58
77.5
76.5
80
75.5
78
80.5
81
81
79
78
78.9
1.62
81
80.5
77
78.5
79
79.5
80.5
81
80.5
77
79.5
1.43
* See Figure 6-2 and 6-3
** Maximum directivity factor = antilog (
L -L
max
10
7-18
-------
330
30°
300
210
60°
120"
150"
Figure 7-4. Horizontal Directivity of Ingersoil-Rand
DXL 900S Compressor
7-19
-------
SOUND POWER CALCULATION
Because portable air compressor noise may, in part, be defined in terms
of sound power, sound power levels calculated using data acquired by the CAGI/
PNEUROP method, with and without the overhead microphone position point,
were compared with levels calculated from data acquired by more conventional
means, i. e., by microphones located at the center of surfaces of equal area on
the surface of an imaginary hemisphere about the sound source.
The results presented in Table 7-7 show that power levels calculated from
the CAGI/PNEUROP 4 and 5-point data compare well to those calculated using
the more precise 10-point hemispherical measurement method. An average
difference of only 0.6 dB was found in each case. These results occurred pri-
marily because the compressors tested were not very directive. In the extreme
case of a completely nondirective compressor, all methods would yield exactly
the same results. In fact, only one sound level measurement would be re-
quired.
7-20
-------
Table 7-8
SOUND POWER LEVEL COMPARISONS
Compressor
Atlas Copco
VSS 170
Worthington
160 QT
Worthington
750-QTEX
Ingersoll- Rand
DXLCU 1050
Inger s oil- Rand
DXL 900S
Gardner-Denver
SPQDA/2
(Full Power)
Gardner- Denver
SPQDA/2
(Idle)
PWL*
(4pt.)
(dBA)
96.4
100.9
99.9
in. 4
102.2
105.0
96.6
PWL*
(5pt.)
(dBA)
96.3
100.5
99.9
117.2
102.1
105.1
97.1
PWL*
(10 pt. )
(dBA)
96.7
102.1
100.2
117.5
103.9
104.5
97.5
PWI^O
minus
PWL,
4
0.3
1.2
0.3
0.1
1.7
-0.5
0.9
PWL1D
minus
PWLr
5
0.4
1.6
0.3
0.3
1.8
-0.6
0.4
*PWL = Sound power level
7-21
-------
LOW FREQUENCY NOISE
The A-weighting network of sound level meters attenuates low-frequency
noise; e.g., -39.4 dB, -26.2 dB, -16. IdB, and -8.6 dB at frequencies of
[18]
31.5 Hz, 63 Hz, 125 Hz and 250 Hz, respectively. As such, great differen-
ces can result between A-weighted levels and the unweighted (relatively
speaking) C-weighted levels. The significance of this is the possibility that
while a compressor's A-weighted data may be decreased, the C-weighted level
could conceivably remain the same, or could in fact increase. Though A-
weighted sound level decreases might adequately reduce health and welfare
impact. C-weighted noise control is desirable as well to preclude the escala-
tion of overall unweighted compressor noise.
Tables 7-9 and 7-10 show dBC/dBA differences for standard and silenced
portable air compressors, respectively. As shown, dBC/dBA differences up
to 28 dB are noted for silenced models. Figure 7-5 gives insight into the
cause for the greater dBC/dBA difference for the silenced models. In the
figure, it is shown that a lower dBA level for the silenced unit has been a-
chieved by a shift of peak sound levels to the low frequency range. Note that
while the A-weighted sound level of a compressor has been reduced by 6dB
(standard to silenced) the C-weighted value has been reduced by only IdB as
a result of the different weighting characteristics of the A and C networks.
In view of (1) the fact that a A-weighted noise reduction does not neces-
sarily imply an attendant C-weighted reduction and (2) the desire to control
the C-weighted level of compressor noise as well as the A-weighted value,
Figure 7-5 was prepared from the data of Tables 7-9 and 7-10 to give insight
into achievable C-weighted levels. The line in Figure 7-5 represents a best-
fit curve through the data points and indicates that a dBC minus dBA limit of
20dB would be a reasonable control limit.
7-22
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ACOUSTIC VALUE OF PORTABLE AIR COMPRESSOR DOORS
At a construction job site, portable air compressor equipment compart-
ment doors are often left open because of the operators' misguided intent of
furnishing more engine and compressor cooling. Actually, portable air com-
pressors are designed to provide adequate cooling with the access doors
closed. Since the access doors, when closed, eliminate a direct line of sight
to the engine (which is the major source of noise) an escalation of portable air
compressor noise is expected to occur when the doors are left open.
Six tests were conducted, three of the standard units and three of silenced
units, to assess the magnitude of escalation of portable air compressor noise
due to opening the access doors. Table 7-11 presents the results of the tests
of the standard units; shown is a noise increase of up to 5dB.
Table 7-11
EFFECT ON STANDARD PORTABLE AIR COMPRESSOR
NOISE OF OPENING THE EQUIPMENT COMPARTMENT
ACCESS DOORS
Manufacturer
Ingersoll-Rand
Jaeger
Jaeger
Model
DXL 1200
A
E
A-weighted Increase, dBA*
5
1.5
1.5
* Difference in level at the right side of the unit between door open and
closed position.
7-26
-------
Table 7-12 list the results for the silenced units; shown is an increase up
to 12 dBA when the access door of the Worthington 750 QTEX was left open.
Table 7-12
EFFECT ON SILENCED PORTABLE AIR COMPRESSOR NOISE
OF OPENING THE EQUIPMENT COMPARTMENT ACCESS DOOR
Manufacturer
Worthington
Atlas Cop co
Worthington
Model
160 QT
VSS170Dd
750 QTEX
A-weighted Increase, dBA
5
11
12
In view of the data of tables 7-11 and 7-12, portable air compressor equip-
ment compartment access doors must remain closed during compressor oper-
ation to preclude acoustic degradation of the portable air compressor.
PORTABLE AIR COMPRESSOR NOISE PROPAGATION
If the propagation of sound away from compressors to points more than
several hundred feet in the community is of concern, then meteorological fac-
tors (wind, temperature, humidity, and precipitation) may be significant. In
addition, obstacles and variations in ground cover may be important. For
shorter distances, the propogation may be complicated by interference pheno-
mena between the sound waves radiating directly from a source and those re-
flected from nearby surfaces, especially the ground. ' '
7-27
-------
Ground Reflections
Contributions arising from constructive/destructive interference between
direct sound waves and sound waves reflected from the ground plane at measure-
ment positions have been evaluated. Figure 7-6 shows A-weighted compressor
noise measured 7 meters away from a compressor at various heights above the
ground. While it is shown that sound level variations in some 1/3 octave bands
of up to 7 dBA from one height to another, the variation in overall sound level
is * 1 dBA from the central position.
The effects of ground reflections on the measured sound levels at the 7-
meter positions appear to be "averaged out" by the spatial distribution of the
individual noise generating components of the compressor. Thus, it is con-
cluded that at 7 meters ground reflections do not modify the measured sound
levels.
Path Discontinuities
As compressor noise propagates away from the source, propagation path
discontinuities can affect the sound waves. The six configurations in Figure 7-7
comprise those typical at construction sites. The half sapce shown in this figure
represents the area surrounding a compressor during testing per ISO-2151-1972
or when used during construction in a residential or light industrial area. Sound
propagating in a half space is subject to the interference effects discussed pre-
viously. When a compressor in a residential or light industrial area is next to a
building, the buildings usually are far enough apart to be described by the "L"
[221
space in Figure 7-7. Anderson reported that sound propagates in an "L" cross
section as it does in free space. The sound level at a point in an "L" space is
expected to be on the order of 3 dB higher than the sound level measured at the
same point in a free field over a reflecting plane, because the sound energy is con-
centrated in a smaller volume in an "L" space than in a half space. Francois and
F191
Fleury1 J measured a corresponding 2 dB increase in compressor noise in an "L"
space.
7-28
-------
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HALF SPACE
(NO CORRECTION)
BUILDING
Jj,
"L" SPACE
(ADD 2 dB)
BUILDING
BUILDING
Ji
W/////////////A
"U"SPACE
(ADD 4 dB)
JJ.
fWMmfift
VAULT
(ADDIOdB)
BUILDING
BARRIER
BARRIER
(SUBTRACT 17 dB)
BUILDING
BARRIER
(SUBTRACT 20 dB)
BARRIER AND PIT
Figure 7-7. Configurations of Locations of Compressors at Construction
Sites (Corrections are for Sound Levels at 7 Meters from the
Machine Surface When Compared to the Half-Space Levels)
7-30
-------
The "U" space in Figure 7-7 is representative of city "canyons" formed
by a street or alley and the vertical walls of nearby buildings. Appendix A of
Reference 10 discusses the propagation of sound in city canyons in more detail
and also includes the results of calculations carried out using an extension of
[23]
the theory of Weiner, et al. The theory shows that a nondirectional source
produces sound levels in a typical city canyon that are 6 dB higher 100 feet from
[19]
the source than the levels present in a half space. Francois and Fleury
measure a corresponding 4-dB increase for a "U" space of different dimensions
from the "U" space analyzed in Appendix A of Reference 6.
There is some concern that the sound levels experienced in the upper
stories of city buildings might be unusually high if the observers are located
above a compressor with pronounced vertical directivity, particularly if the
compressor sound is confined within a city canyon. However, Appendix A of
Reference 6 shows that an air compressor that radiated sound four times as
efficiently (in terms of intensity) in the vertical direction as in the horizontal
direction will expose people in city buildings to less than 4 dB higher sound
levels than an air compressor that uniformly radiates an amount of sound
energy. Thus, this assertion does not appear to be valid.
A compressor operated under a bridge or overpass can be described in
terms of the vault space in Figure 7-7. The sound levels generated in such a
space can be more than 10 dB higher than the sound levels generated in a half
space.
The barrier and pit configurations depicted in Figure 7-7 are typical of
construction sites in cities. Usually the construction of a building in a city
center begins with the erection of a tall broad fence. During the initial ground
breaking, compressors operate at ground level behind the fence. As excavation
proceeds, compressors operate within the pit dug for the basement floors. Cal-
7-31
-------
culations presented in Appendix B of Reference 24 show that pits and barriers
can reduce the noise levels experienced by outdoor ground level observers by
as much as 20 dB below the levels experienced in an unobstructed half space.
The benefits to upper story observers in buildings across the street depend on
the construction stage, on the observer's elevation, and on if there are verti-
cal reflecting surfaces in addition to those shown in the barrier configurations
in Figure 7-7.
Extrapolation of Data
The near and far field are described in terms of wave propagation. The
near field is close to the source, though how far it extends depends on the wave
length of the radiated sound. Normally, the acoustic near field extends a dis-
tance of about one quarter of a wave length. Sound pressure fluctuations with
the near field correspond to the hydrodynamic response of the fluid to the
motion of the adjacent surface. In the far field, the sound pressure fluctua-
tions are caused by the propagation of sound waves away from the source.
Typically, noise decreases 6 dB per doubling of distance away from the bound-
ary between the near and far field. Within the near field, no typical decay rate
is known. Thus, projection of far field levels from near field levels using the
6 dB doubling rule may not give accurate results. If thel meter CAGI/PNEUROP
points in the near field are used for far field noise predictions, inaccurate
estimates may result.
One way to verify that the 1 meter data are taken in the near field is to
compare 1- and 7- meter levels. A histogram of the difference in these levels
is presented in Figure 7-8 for the 26 compressors that were measured. This
figure clearly shows negligible correlation between the two sets of measure-
ments. Spherical spreading of the sound field between 1 and 7 meters would
yield about 17 dB difference between these two points. No compressor showed
7-32
-------
this large a decrease. Moreover, the differences are randomly spread from
5 to 15 dB.
The preceding results indicate that it is erroneous to use 1-meter levels
to calculate far-field noise levels and vice versa, for that matter. Further,
inaccurate sound power estimates might also result from similiar predictions.
To see if 1-meter data are useful in determining the noisiest side of the ma-
chine, the three dimensional histogram of Figure 7-6 was derived. The loud-
est side at 7 meters is plotted against the noisiest side at 1 meter in this
figure. * Again, the 1-meter data show poor correlation with the 7-meter data,
in that in half the cases the noisiest direction is incorrectly indicated. Good
correlation would place most on the measurements on the diagonal line in
Figure 7-9.
* The abscissa in Figure 7-8 use the following convention: 0 degrees is the
forward direction, with angular position measured clockwise looking down on
the compressor. (See appendix C of Reference 6).
7-33
-------
s
•s
I
7 8 9 10 11
Difference In Sound Levels, dB(A)
~ [A(7M)
12
13
14 15
Figure 7-8. Comparison of 7-M with 1-M CAG1/
PNEUROP Average Sound Levels
7-34
-------
» 5
§
1 4
"S
3
0° 90° 180°
Seven-Meter Maximum Point
270°
Figure 7-9. Histogram Comparing Maximum
Point at 7-M and 1-M Distances
7-35
-------
Section 8
AVAILABLE NOISE CONTROL TECHNOLOGY
UNITED STATES TECHNOLOGY
In 1968, a major manufacturer of portable air compressors demonstrated
significant noise reduction by the use of muffling devices and acoustic enclo-
[25, 26]
sures. Since then, numerous manufacturers in the United States and
abroad have applied various degrees of noise control technology and have re-
duced portable air compressor noise. Figures 8-1 and 8-2 show two examples
of effective noise control. In this section, the current state-of-the-art of com-
pressor noise control is discussed and noise control techniques is summarized.
Most large air compressors are diesel engine driven, screw type compres-
sors. The intermediate sizes are diesel and gasoline engine driven, screw and
rotary type compressors while the smaller types are primarily gasoline engine
driven, screw, rotary and reciprocating type compressors. For all standard
types, the major noise sources are the driving engine itself and the fan associa-
ted with the engine and compressor cooling air system. A description of the
various types of compressors is contained in References 5 and 6.
Application of acoustic insulation, effective mufflers, shock mounts, damp-
ing material, and some fan, cowling, and duct hardware modifications/improve-
ments generally describe the technology used to quiet compressors. Use of
this technology has produced the mean noise reductions listed in Table 8-1.
8-1
-------
O
H
m
-» m
3*
E
-------
100
90
80
o
is
•S 70
0)
w
60
50
Unsilenced Unit
I
Silenced Unit
< H 63 125 250 500 1000 2000 4000 8000
Octave Band Center Frequencies, Hz
NOTES: (1) CAGI/PNEUROP Position 9
Figure 8-2. Noise Control Applied to the Atlas-Copco Model VT85 Dd
8-3
-------
Table 8-1
MEAN NOISE REDUCTION BETWEEN "STANDARD", QUIETED",
AND "QUIETEST" UNITS
Standard to
quieted units
Quieted to
quietest units
Gasoline
6.7 dB
3.8 dB
Diesel
Below 500 CFM
9.7 dB
6.4 dB
Diesel
Above 500 CFM
14. 1 dB
5.2 dB
The values listed in Table 8-jf may be compared with the potential for noise
reduction discussed in Reference 3. As indicated in Reference 3, the potential
noise reduction was 5 ... and 10 dB by the use of improved intake silencers and
engine mufflers, respectively. Note that the 5 dB and 10 dB noise reductions
are not additive, because the total noise reduction is dependent upon individually
reducing the noise level of all the major sources of noise. To determine more
accurate potential noise reduction capabilities for compressors, a study was
conducted of the three quieted units:
1. A gas engine powered air compressor
2. A diesel engine powered air compressor of less than 500 CFM capacity
3. A diesel engine powered air compressor of greater than 500 CFM
capacity
The purposes of the study were to determine the major sources contributing
to compressor noise, the effectiveness of the noise control techniques used by
the manufacturers, and the evaluation of additional noise control required to
reduce each unit's noise to 65 dBA, measured at 7 meters from the unit.
Gas Powered Engine Compressor
A Worthington 160 QT was selected for analysis. Significant noise sources
8-4
-------
oJ' this unit are the compressor, the engine and its cooling fan, the exhaust and
[7]
muffler shells, and the air intake.
The engine and compressor assembly radiate noise directly, with the com-
pressor assembly somewhat attenuated by the surrounding air-oil tank. In
addition, since they are rigidly attached to the chassis and the shell of the ma-
chine, engine and compressor vibration is transmitted directly to the frame and
outer sheet metal, which also vibrate and radiate noise.
The engine cooling fan can produce considerable broadband noise as the re-
sult of design practices that would cause the fan to excessively agitate the air
surrounding the fan. In addition to generating noise, such practice would also
reduce efficiency of both the fan and the overall cooling system.
The engine exhaust and muffler arrangement produces noise because of
the direct discharge; it can also radiate noise from the large muffler shell vi-
brating with the internal pressure fluctuations. The air intake system supplies
the engine and compressor through a common air filter and silencer. The two
air induction pressures thus combine to form a separate noise source.
The noise level at 7 meters to the right side of the unit (as sold) was 76 dBA.
The contribution of the principal noise sources to this level are tabulated below
in Table 8-2.
Table 8-2
WORTHINGTON COMPRESSOR 160 QT COMPONENT NOISE LEVELS
Component
dBA
Engine and Compressor Casing
Engine Cooling Fan
Muffler Shell
Exhaust
Intake
74
69
66
62
61
8-5
-------
The individual noise sources were carefully studied to determine the meth-
odology to further reduce the unit's noise level to the 65 dBA study level. By
use of the following noise control techniques with resulting attenuation of Table
8-3, a compressor noise level of 65 dBA at 7 meters could be achieved.
Table 8-3
PORTABLE AIR COMPRESSOR NOISE REDUCTION
Source
. Engine and
compressor
casing
. Engine cooling
fan
. Muffler shell
. Exhaust
. Intake
Noise Control Technique
Vibration isolation plus increased
transmission loss through
side doors
Shroud redesign, blade twist
and reduced fan speed
Lagging with acoustic insulation
Additional muffling
Improved silencer
Noise Reduction
14 dB
11 dB
10 dB
5 dB
4 dB
Diesel Powered Compressor, less than 500 CFM
The quieted Atlas Copco Super Silensair VSS170 Dd was selected for analy-
[7]
sis. This unit produces approximately 72 dBA at 7 meters distance from the
unit. The analysis of the unit's noise signature indicates that the principal
noise sources are the engine casing, engine exhaust, engine intake, compres-
sor casing, and compressor cooling fan, each of which produce the sound levels
at 7 meters listed in Table 8-4.
8-6
-------
Table 8-4
ATLAS COPCO COMPRESSOR VSS170 Dd COMPONENT NOISE LEVELS
Component
dBA
Engine Casing
Engine Exhaust
Engine Intake
Compressor Casing
Compressor Cooling Fan
63
60
61
64
63
Mid-frequency silencing is achieved by use of an enclosure having side
walls and end doors lined with a foam type acoustic absorption material. The
enclosure has built-in ducting for the engine and compressor air intake and
cooling. Cooling air exhausted from the diesel engine and the compressor and
intercooler is ducted through another part of the enclosure prior to discharge.
These ducts are primarily effective in blocking direct, line-of-sight, internal
noise radiation from the engine and compressor to the ambient. An additional
5 to 7 dB in radiated sound could probably be obtained by employment of the
following noise reductions techniques.
1. Application of damping material to the enclosure panels; damping
will reduce panel vibration levels and improve panel transmission loss
due to the added mass.
2. Increasing the internal sound absorption by (a) treating a larger amount
of the internal surface area and (b) using a thicker absorptive material.
Note: the absorptive material should be treated to prevent degradation
due to contamination.
3. Use of a more effective vibration isolation mount to decouple the engine
and compressor from the chassis.
4. Use of a more effective diesel exhaust muffler.
By using the above noise control techniques, the attendent 7 dB overall
reduction could result in a compressor noise level of 65 dBA at 7 meters.
8-7
-------
Diesel Engine Powered Air Compressor Greater than 500 CFM Capacity
The "Blue Brute" 750-QTEX single stage, portable, rotary screw com-
[71
pressor manufactured by Worthington CEI was selected for study. The
750-QTEX is a quieted unit; it has been silenced to product 75 dBA at 7 meters.
Among diesel powered compressors delivering greater than 500 CFM, the
750-QTEX is one of the quietest. It is only 1. 5 dB noisier than the mean for the
lowest decile.
The technology by which the 750-QTEX has been quieted is also characteris-
tic of the quietest compressors in its category. It has rubber engine mounts,
nonrigid hose coupling, sealed doors, damped panels, interior sound absorption,
silenced fan louvers for cooling air intake and exhaust, 2-stage custom designed
muffler, bottom pan, and a special cooling fan. Principal sources of the noise
are listed in Table 8-5 along with their individual noise levels.
Table 8-5
WORTHINGTON COMPRESSOR 750 QTEX COMPONENT NOISE LEVELS
Component
Engine and compressor casing
Engine cooling fan
Muffler shell
Exhaust outlet
dBA
69
6205
70
67
The 750-QTEX enclosure presently provides adequate noise reduction of
engine and compressor airborne sound, except at the cooling air intake and
exhaust ducts. Additional noise reduction is possible with design improvement
ryi
of both the ducts and the material used for acoustic absorption. Analysis
-------
showed that the 750-QTEX cooling fan is lightly loaded (aerodynamically). A
noise reduction of 3 dB could be effected by fan redesign to provide greater fan
loading (aerodynamic). The muffler shell radiated noise level can be reduced
by building an enclosure around the shell, whereas, exhaust outlet noise can be
reduced by employment of a manifold type muffler. Use of the noise reduction
techniques discussed can result in achievement of a 65-dBA compressor.
EUROPEAN TECHNOLOGY
Atlas Copco and CompAir compressors use a double-wall construction,
with cooling air ducted between the walls. All the "Super Silenced" Atlas Copco
air compressors are the reciprocating type. Discussions with Atlas Copco
indicate that reciprocating air compressors are more efficient, with less heat
rejection. Atlas Copco uses air cooled engines with cooling fans built in,
which demonstrate a much better performance than the fans measured on
domestic air compressors. CompAir compressors use a sliding vane or
rotary screw type compressor with a water cooled Perkins diesel engine. The
pusher type fan is well shrouded. Proper air flow through either unit requires
door-shut type operation. The noise control technology used in Europe is
similiar to that used in the United States, but a more systematic approach is
applied to quieting air compressors. Noise control design is more from the
frame up and uses an integrated approach rather than merely adding on quieting
silencers. Foreign "super silenced" air compressors tend to have a boxy look.
The outer enclosure is double walled and serves as an air duct and silencer as
well as a barrier to engine and compressor radiated noise.
To achieve low noise levels, enclosures should be absolutely sealed under
operation in order to avoid noise leaking out through even small openings. It
has been reported that large compressors emitting less than 65 dBA under full
F271
power are already on the market.
8-9
-------
Section 9
ECONOMIC STUDY
Section 6 of the Noise Control Act of 1972 provides that the Administrator
of the Environmental Protection Agency (EPA) shall establish noise emission
standards (where feasible) on products that are found to be major sources of
noise or that are in specific product categories named in the law. This regu-
latory program is applicable to construction equipment products in both instances.
Section 6 further states that the regulation:
shall include a noise emission standard which shall set limits on noise
emissions from such product and shall be a standard which ... is
requisite to protect the public health and welfare, taking into account the
magnitude and conditions of use of such product . . . the degree of noise
reduction achievable through the application of the best available technology,
and the cost of compliance . . . Any such noise emission standards shall
be a performance standard. In addition, any regulation . . . may contain
testing procedures necessary to assure compliance with the emission
standard in such regulation, and may contain provisions respecting instruc-
tions of the manufacturer for the maintenance, use, or repair of the product.
The EPA, to adequately address the potential economic impact of noise
emission regulations upon the various affected societal units (industry, user,
suppliers), acquired data that related to pricing characteristics, dollar volume
and unit volume of the portable air compressor market. Additionally, informa-
tion was developed that related to the costs-to-quiet portable air compressors
using the technology currently being utilized and also the best available technology,
whether or not it was actually being applied. The information that was developed
and that related to the market and the costs-to-quiet formed the background for
the economic impact/analysis report the major conclusions of that report are
contained in Section 9 of this document.
The basic objective of the study was to assess the economic impact of the
adoption of alternate noise emission standards on the portable air compressor
industry. This assessment included consideration of the impact on raw material
9-1
-------
and component suppliers, distributors, manufacturers, end users, and the gen-
eral public. The industry-wide impact and the distribution of impacts on market
segments and individual companies were determined. The impact on key govern-
mental policy concerns such as employment and the balance of trade was also
assessed.
COST DATA
The following discussion presents cost data for quieting portable air com-
pressors. The data addresses the costs to quiet compressors utilizing currently
available technology as well as the best available technology. From the data the
cost and economic impact were developed.
TOTAL SALES VOLUME
All portable air compressor pricing is based on discounts from published
list prices. The manufacturers published discount schedule typically ranges
from 20 to 25%. However, discounts to distributors can vary from 15 to 45%,
depending on volume and other transaction factors.
According the the United States Department of Commerce, prices of
portable air compressors rose 24% between 1967 and 1972, or at a compound
annual rate of 4.4%. This price trend is expected to continue because of the
general increases in labor and material costs. Table 9-1 presents the average
prices of portable air compressors by power source and capacity-cfm.
Table 9-1
ESTIMATES OF PORTABLE AIR COMPRESSOR
AVERAGE LIST PRICES - ALL MODELS
Capacity-cfm and
Power Source Type
75 - 124 Gas
124 - 249 Gas
124 - 249 Gas
250 - 599 Diesel
600 - 899 Diesel
900 and over Diesel
Estimated Average List Price,
$3,982
5,741
6,791
17,509
29,376
48,918
9-2
-------
DOLLAR VOLUME
Sales of portable air compressors are sensitive to government and private
funding of construction activity. Sales of large units have historically followed
trends in the construction industry, while smaller units have followed the
general economy. Dollar value of portable air compressor shipments has
fluctuated between $58.7 million and $89.7 million during the years 1967-1972.
Portable air compressor sales are projected to reach approximately $93 million
during 1973.
Table 9-2 presents the value of total portable air compressor shipments
during 1967-1972. No adjustments have been made to account for inflation.
The data of Table 9-2 were derived from information made available by the
Compressed Air and Gas Institute and the Department of Commerce. The
derivation of these data is discussed in Reference 8.
Table 9-2
ESTIMATED DOLLAR VALUE OF ANNUAL SHIPMENTS OF
PORTABLE AIR COMPRESSSORS: 1967-1972
Year
1967
1968
1969
1970
1971
1972
Value of Shipments
$ 58, 700, 000
59,915,000
75,295,000
70,295,000
74, 131,000
89,732,000
PERCENT DISTRIBUTION BY TYPE COMPRESSOR
The portable air compressors currently manufactured are primarily powered
by gasoline or diesel engines. Three basic design types of compressors are
used in portable air compressors: rotary screw, sliding vane, and reciprocating.
Table 9-3 illustrates the distrubtion of engine and compressor type according to
engine capacity.
9-3
-------
Table 9-3
DISTRIBUTION OF ENGINE TYPES AND COMPRESSOR DESIGN TYPES
ACCORDING TO RATED ENGINE CAPACITY IN CFM AT 100 PSIG
Compressor Type
Reciprocating
Vane
Screw
All types
75-200 cfm
Gasol Ine
1C. 6?
2!>.6?
15. ^
57. 6?
Diesel
10. 3^
19.2*
12.8?
12. 3?
Gasol 1ne
and
Diesel
26. y?
41. 8X
29.2*
99.9?
201-500 cfm
Gasol 1nc
0?
10.31
2.6?
12.9?
Diesel
30. B?
33.3?
23. U
67.2?
Gasol 1 ne
and
Diesel
30.0?
13. c?
25.7?
100.1?
Above 500 cfm
Gasol Ine
0*
0*
0%
Of
Diesel
6.6?
m
76. 3?
100.1?
Gasol Ine
and
Diesel
6.8?
17X
76.3?
100.1?
UNIT VOLUME
Table 9-4 presents total unit shipments which presents a clearer picture of
the portable air compressor market than does dollar value. Dollar value is not
an accurate form of relative importance due to inflation and industry price
increases based on improved features and performance. Furthermore, dollar
sales by size category provides a distorted view of the market due to the high
purchase price of the larger units.
Table 9-4
TOTAL PORTABLE AIR COMPRESSOR UNIT SHIPMENTS, 1967-1972
Year
1967
1968
1969
1970
1971
1972
Unit Shipments
9,969
9,719
12,277
9,973
9,901
12, 154
Yearly Change (%)
-2.5
25.8
18.8
-.7
22.8
9-4
-------
Table 9-5 concentrates on 1972 portable air compressor sales and breaks
it down by power source type and capacity.
Table 9-5
PORTABLE AIR COMPRESSOR 1972 SALES BY POWER SOURCE TYPE
AND CAPACITY CATEGORY
Power Source Type
and capacity cfm
75 - 124 gasoline
125 - 250 gasoline
125 - 249 gasoline
250 - 599 diesel
600 - 899 diesel
900 and over diesel
Total
Unit Shipments
3,082
4,827
2, 101
576
1,095
473
12, 154
Total (%)
25.4
39.7
17.3
4.7
9.0
3.9
100.0
COST PER CFM
The EPA in its initial evaluation of the portable air compressor market
divided compressors into six categories based on engine type and whether or
not they were "standard" or "quieted" units. This division was done to get as
clear a picture as possible as to the price differentials.
Provided in the following table, for each category, is the mean and standard
deviation of price/cfm and sound levels at 7 meters (measured according to
ISO 2151-1972). Accordingly, Table 9-6 presents a summary of the present
state of noise emissions and price of portable air compressors.
9-5
-------
Table 9-6
PRESENT STATUS OF PORTABLE COMPRESSORS
WITH RESPECT TO NOISE EMISSIONS AND PRICE PER RATED CFM
Nur.ber of Units in
Sanplcr.
rrlce/cfri
Mean
Standard devia-
tion
SPL at 7m
Mean
Standard devia-
tion
Quietest Machines
(Lowest decile)
No. In decile
I'ean SPL at 7m
Deviation of
avei'p.Gt price in
lov.-eit decile
from rnonti price
of quieted
Gasol 1ne Driven
StanJard
3?
$39.2?
$ 1.10
82.8 dB(A)
'1.92 dB(A)
3
72.6 dB(A)
+$5.12
Quieted
26
$13.32
$ 6.10
76.1 dB(A)
2.10 dB(A)
3
72.3 dB(A)
+$5.11
Diesel Driven
Below 501 cfm
Standard
15
116.16
$ 1.57
86.1 dB(A)
3.35 dB(A)
6
82 dB(A)
+$0.13
Quieted
35
$52.11
$ 8.30
76.1 dB(A)
1.07 d3(A)
1
70 dB(A)
+$10.23
Above 500 cfm
Standard
32
$13.57
$ 3.56
92.8 dD(A)
1.03 dB(A)
1
87.5 dB(A)
+$0.31
Qait'tcd
21
$18.70
$ 3.16
78.7 dB(A)
3.90 dB(A)
2
73.5 dB(A)
+$2.50
A 10.2 dB mean difference between "standard" and "quieted" compressors is
offered at a mean price difference of $5. 05 per cfm. Of particular interest is
the fact that in the "standard" categories, the quietest machines are priced on
the average at only $2. 05 above the mean price whereas the quietest of the
"quieted" machines is on the average 9.1 dB quieter than the quietest; "standard"
machine but is priced about $5.96 above the mean price of the "quieted" machines.
NOISE LEVELS FOR STUDY
Two studies have been performed to estimate the cost to quiet portable air
compressors.
9-6
-------
In the initial study, noise levels associated with three broad categories of
portable air compressor capacities were evaluated. The levels selected for
study were based on sound level data of 194 portable air compressors repre-
senting about 55% to 65% of the all models offered for sale. The levels selected
are listed in Table 9-7 along with underlying rationale for their selection.
Table 9-7
INITIAL SOUND LEVEL LIMITS SELECTED FOR STUDY
Level One
Level Two
Level Three
Gasoline Driven
all cfm
Ratings
76 dBA
73 dBA
65 dBA
Diesel Driven
Below 501
cfm
76 dBA
70 dBA
65 dBA
Diesel Driven
Above 500
cfm
78 dBA
73 dBA
65 dBA
Notes: (1) Levels constitute a. "not to exceed" criteria
(2) Average sound pressure level in dBA at 7 m. according to
the recommended measurement practice of ISO 2151-1972
modified to include an overhead measurement.
(3) Level One corresponds to the average quieted portable air
compressor model currently on the market,
(4) Level Two corresponds to the lowest decile of the quieted
portable air compressor model currently on the market.
(5) Level Three corresponds to an analytical estimate of a
possible portable air compressor noise emission level
based on a number of assumptions.
(6) The value for Level One and Level Two are arithmetic
averages. The information required to weight the noise
levels by relative model sales is not available. Weighting
by estimates of capacity and/or manufacturer market share
was not utilized.
9-7
-------
These data were used to assess the cost and economic impact associated with
achieving the levels selected for study. The results of the study are presented
in Reference 8.
In the second study, a single sound level value for all portable air com-
pressors, independent of capacity, was selected for each level. The selected
values are listed in Table 9-8.
Table 9-8
SOUND LEVELS SELECTED FOR SUBSEQUENT STUDY OF
ALL PORTABLE AIR COMPRESSORS
Level One 76 dBA
Level Two 73 dBA
Notes: (1) Levels constitute a "not to exceed" criteria
(2) Average sound pressure level in dBA at 7 meters accord-
ing to the recommended practice of ISO 2151-1972 modified
to include an overhead measurement.
The following considerations led to the selection of the single sound level
values:
1. They would enable EPA to make a more reasoned choice as to the
levels ultimately selected for the proposed regulation in that there
would be several additional data points around which the economic im-
pact analysis could be constructed.
2. A single, uniform level for all compressors would bring the costs to
quiet compressors into approximately the same price per cfm range.
This would equalize costs and tend to mitigate any significant market
shifts from one compressor size category to another.
9-8
-------
3. It has been demonstrated that there is little difference in the noise
levels porduced by quieted compressors regardless of cfm capacity.
Thus for this reason alone, it would make little sense to apply differing
noise regulatory levels.
4. A single noise level would create less confusion or uncertainty in
enforcement at the Federal, state or local levels. The enforcement
official would have to keep only one level in mind. There would be no
necessity for extensive cross-checking of model, cfm capacity, or
production year. Additionally, it would not matter if the compressor
data plate which would also contain the permissible noise level, were
missing or obscured.
Missing from Table 9-8 is a level-three value of 65 dBA. The 65 dBA value
represents an engineering prediction for an attainable noise level, with the
assumption that analytical estimates of noise reduction will be achieved in
practice. Although estimates of the cost to quiet portable air compressors to
[5 71
65 dBA were made, ' EPA is not satisfied with the estimates. In view of the
foregoing, evaluation of the economic impact associated with quieting portable
air compressors to 65 dBA was not made. Thus, the data reported in the dis-
cussions that follow reflect the economics of quieting all compressors to either
76 or 73 dBA.
ESTIMATED COSTS-TO-QUIET PER CFM
The costs of quieting portable air compressors were estimated in terms of
list price differentials per cfm of compressor capacity (References 5 and 7 pro-
vides details on the estimating procedure employed). Table 9-9 lists the estimated
costs to quiet for the sound levels of Table 9-8.
9-9
-------
Table 9-9
ESTIMATED COST OF QUIETING PER CFM
BASED ON ANALYSIS OF LIST PRICE DIFFERENTIALS
Capacity/ Engine
Category
Gasoline Engine
Below 251 cfm (all)
Diesel Engine
Below 501 cfm
Diesel Engine
Above 500 cfm
Current Mean
To Level One
Model Type *
Standard
($/ cfm;
$ 6.11
8.40
7.30
Quiet
($/cfin)
2.45
3.19
2.50
Level One
To Level Two **
All Models
($/cfm)
6.43
5.79
1.60
These costs reflect quieting a typical average model to each level on a
"not to exceed" basis incorporating a 2 dBA manufacturing tolerance based on
the A-weighted sound level reduction required from the mean noise levels.
From the data in the table it can be noted that the costs required to reach Level
Two are significantly lower per cfm for the units above 500 cfm capacity.
This indicates an increase in the economies of scale of larger machines.
METHODS TO ASSESS TOTAL COST
The cost to quiet portable air compressors was estimated using the cost
and technology data discussed previously. Estimates were developed on the
basis of full margin and incremental margin costs, which are defined below.
* Current mean dBA values of Table 7-5(a) to 76 dBA
** 76 dBA to 73 dBA
9-10
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1. Full Margin Costs - Full margin method is based on actual increase in
direct material purchased and direct labor of fabrication and assembly
as reflected in the accounting system. It allocates the full margin of
other costs (overhead, profit, etc.) at the same rate to a quieted unit
as is currently allocated to a standard unit. This method can be
expected to overstate the actual cost change.
2. Incremental Margin Costs - The incremental margin cost reflects an
adjustment to the full margin data. Full margins include overhead
accounts that will not change with the introduction of quieting or
change less than the estimates based on application of margin dollars
at the same percentage rate as on a standard machine. The incre-
mental margin rate that has been estimated reflects inclusion of
changed costs in overhead accounts and profit margins required to
fully reflect all incremental costs and profits on increased investments
(i.e., raw material inventories) as well as direct labor and material
costs designed to leave the company in the same overall position as
with current production. This method attempts to reflect the actual
cost change incurred.
The basic findings using estimating techniques described above are as
follows:
1. Full Margin estimates are often above the list price estimates parti-
cularly without the 2 dBA tolerance considered.
2. Incremental Margin estimates are below the list price estimates for
the smaller air flow capacities and about the same as the estimates
with tolerance for the larger air flow capacities.
Neither of these estimating techniques takes into account the marketing
discounts that the industry typically gives. These discounts may range from
15 to 40% of the list price.
9-11
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A detailed discussion of the methodology used and the results obtained is
contained in Reference 8.
ECONOMIC IMPACT ANALYSIS
The economic impact analysis that follows is built upon the cost data pre-
sented in the discussion of Cost Data. The economic impact analysis study was
separated into the following six segments:
1. Volume Impact - This segment includes the analysis of chamges in
industry volume that will occur relative to a baseline forecast.
2. Resource Costs - This segment includes the cost of the resources
used to achieve noise abatement and reflects the increased costs to
purchase the noise abated equipment and the cost associated with any
performance and maintenance changes.
3. Market Impacts - This segment includes an analysis of broad changes
in industry and market conditions that might be attendant with the
adoption of the proposed noise emission standards.
4. Foreign Trade - This segment covers an assessment of the impact
on exports, imports and the balance of trade.
5. Individual Impacts - This segment considers assessment of market
impacts that fall differentially on specific companies or industry seg-
ments. The impact shakedown might include economic dislocations,
unemployment, lowered sales volume and profits, and change in market
shares.
6. Disruptive Impacts - This segment considers changes that may occur
in an orderly way within the market in response to various shut downs,
unemployment, etc., that may be caused by the regulation of portable
air compressors.
Two approaches were used to assess economic impact - obtaining direct
estimates based on field interviews and published information and making indirect
9-12
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estimates by analyzing the impacts in a supply/demand model based on economic
theory. The actual measurement of impact was made by projecting market
conditions for 1976 to 1978, both with and without noise emission standards.
Specific impacts were considered in isolation and then the interrelationships
were developed.
It should be emphasized that the following economic impact analysis is based
on estimates. The data used to base the estimated impacts were obtained from
several sources including portable air compressor manufacturers themselves.
Obviously, precise figures as to the real impact of the proposed regulations will
not be available until sometime after the effective date of the regulation.
ECONOMIC IMPACT
The portable air compressor industry/market reaction to adoption of the
noise emission levels that were suggested for study are as follows:
1. The total costs to manufacture the equipment will increase.
2. The manufacturers will pass this cost on in the form of an increase
in the distributor price (list price).
3. The distributor will pass its cost increase on in the form of an increase
in the negotiated customer price.
4. The portable air compressor end user will pass the increase in his
equipment purchase costs on to his customers as an increase in the
price of products and services provided.
5. Final changes in industry prices and volumes will reflect the changes
in portable air compressor purchase prices and operating costs.
6. Ultimately, the consumer will pay a higher price for products due to
the required increased cost to reduce noise.
If there are overall cost reductions, as opposed to cost increases, from the
adoption of noise control technology, competitive pressures will cause cost
decreases to be passed on up the economic chain to the consumer in the form of
lower prices.
9-13
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The scenario under which the economic impacts were estimated is based on
*
the technology and costs contained in References 5 and 7. It is assumed that
the technology and costs provided would be the actual future technology adopted
and costs incurred. This approach is conservative. It is possible, if not likely,
that new technology at lower costs will be developed. Thus, if the current costs
based on an assessment of on the shelf technology are reasonably accurate, they
are essentially an upper bound estimate. Noise standards can be attained at these
costs, but possibly they will be attained at less cost based on better future
technology.
Volume Impact
This discussion analyzes the impact of the noise levels suggested for study
on the volume of production of portable air compressors.
Pricing
Purchasers of portable air compressors will be presented with a price
increase associated with each noise emission level selected for study. Price
increases attributable to sound attenuation and compliance and enforcement
costs were estimated using estimated marginal cost of quieting based on list
price differentials. The list proce was selected as the basis for the economic
impact analysis because it is a conservatively constructed estimate and is based
on the broadest sample of cost and noise suppression data available. It is indi-
cative of the upper bound on the expected economic impact.
Table 9-10 presents estimates for average list price percentage increase
to bring existing models of portable air compressors into compliance with the
Level One and Level Two study noise emission levels.
9-14
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Table 9-10
ESTIMATED AVERAGE LIST PRICE PERCENTAGE INCREASE
BY NOISE LEVEL AND CATEGORY
Power Source Type
and Air Flow Capacity
Gasoline Engine, all cfm ratings
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
Level One
Standard
16. 2%
18.4
14.4
Quiet
6.1%
6.3
2.9
Level Two
33.2%
47.2
20.5
Price Elasticity. Since it is anticipated that the added costs of production
associated with quieting portable air compressors will be passed on to consumers
(buyers of air compressors), the price of air compressors is expected to in-
crease. Rising prices can be expected to result in reduced sales as demand falls
off because users will either find more efficient ways to use gasoline or diesel
engine driven air compressors in an effort to cut costs or will switch to sub-
stitute products that provide a lower cost alternative method of performing the
same work. The degree to which sales will fall depends on the ease with which
buyers can change their compressor use habits in different applications to cut
rising costs.
Contractor studies indicate that the decrease in demand due to price rises is
low until price increases exceed 20 percent of current levels (in constant dollars).
After prices rise in excess of 20 percent, demand falls off more rapidly as it be-
comes worthwhile to substitute hydraulic or electric systems for compressed
air systems.
When price rises are below 20 percent (constant dollars), current air com-
pressor users will probably refrain from widespread immediate substitution
because:
1. Portable air compressors are a convenient power source for many
9-15
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2. Users currently have a high investment in tools that operate on com-
pressed air (costing 10 to 200 percent as much as the compressor).
3. Costs of using compressors can be lowered somewhat without substitu-
tion through more renting of equipment and other practices.
Industry estimates of the price elasticity of demand (percent decrease in
demand due to percent rise in price, n = ~T/ are about 0.35 for price rises
under 20 percent, which is generally considered to be price in elastic.
Contractor studies indicate that the price elasticity of demand is higher when
the price increases are in the 20 to 50 percent range. Price increases of such
significance would be expected to have a major impact on demand for new and
used portable air compressors. Industry estimates of the price elasticity of
demand are 0.9 for compressors below 500 cfm and 0.55 for compressors above
500 cfm. The increase in price elasticity when price increases exceed 20 percent,
occurs because:
1. The price increase is sufficient to cause users to consider replacing
the whole compressed air system, including tools, with a hydraulic or
electrically powered system for some applications, especially when
lighter tools are required. This assumes that the work output of
these competing systems is comparable to that of the compressed air
system.
2. The price increase is sufficient to cause users to replace parts for as
long as possible on old compressors to avoid buying new compressors.
3. The price increase is sufficient to cause increasing use of air com-
pressors that are not regulated, including large stationary compressors,
self-propelled compressors, and power takeoff compressors for use
with engine-powered construction equipment.
9-16
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When prices increase more than 50 percent, the rate of substitution can be
expected to decline and the demand should stabilize because there are a number
of applications in which the portable air compressor performs a function that is
difficult to perform with an alternative power source. However, at such high
prices, it can be expected that less expensive alternatives would be developed
over time to replace the portable air compressor in more and more situations,
unless alternatives subsequently become more expensive due to Federal regulations.
Within the levels under consideration for the proposed standards, Level
One corresponds to the 0 to 20 percent price increase analysis, and Level Two
corresponds to the 20 to 50 percent price increase analysis.
Estimates of required lead times for an orderly adoption of technology
necessary to meet Federal standards vary for each of the levels included in the
proposed standards. BBN estimated a lead time of six months for compliance
for Level One, while the compressor industry estimated 12 to 24 months. For
the purpose of this economic impact analysis, it is assumed that the regulation
will take effect on January 1, 1976. The estimated reduction in sales is shown
in Table 9-11 based on previous elasticity estimates.
Table 9-11
LEVEL ONE - ESTIMATED FIRST YEAR
UNIT REDUCTION FROM BASELINE FORECAST-1976
Power Source and Capacity
Gasoline Engine (all)
Diesel Engine, below 500 cfm
Diesel Engine, above 500 cfm
TOTAL
Unit Reduction
358
148
121
T27
Percent
Reduction (%)
4,5
5.0
4.9
~CT
9-17
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BBN estimated a lead time of 18 months for compliance with Level Two,
while the industry estimated much longer periods. For the purpose of this
analysis, it was assumed that the Level Two regulation would take effect January
1, 1978. The reduction in sal.es is shown in Table 9-12 based on previous
elasticity estimates.
Table 9-12
LEVEL TWO -ESTIMATED FIRST YEAR
UNIT REDUCTION FROM BASELINE FORECAST-1978
Power Source and Capacity
Gasoline Engine (all)
Diesel Engine, below 500 cfm
Diesel Engine, above 500 cfm
TOTAL
Unit Reduction
2, 100
742
244
3, 086
Percent
Reduction (%)
25.6
23.2
9.3
~2~2TO~
These calculations are based on prices of quieted units currently on the
market. To the degree that prices are less than current ones due to production
changeover making the quiet models the standard models, actual reductions in
sales will be less than the estimates in the tables.
Resource Costs
This discussion presents a summary of the resources that will be used to
meet the noise standard at each level. The resource costs are estimated in
three ways.
1. The annual increase in capital cost required by end user industries in
the first year of enforcement.
2. The annual increased annual total costs of the end user industries in
the first year of enforcement.
3. The annual increased total costs of operation for a 100 percent quieted
population of portable air compressors.
9-18
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Resource Cost Factors
The estimates of first-year capital costs for end user industries are
based on the increased purchase price paid and volume of purchases esti-
mated. The pricing is at the list price level. This measure represents
the additional capital that must be financed by end user industries due to
the enforcement of the noise standard.
The resource cost factors included in the estimate of the total annual
increased cost for end users are:
• depreciation
• capital costs
• transportation costs
• operating costs
• maintenance costs
These factors are discussed in greater depth in the Economic/Impact study
(Reference 8).
The analysis has developed both upper bound and a lower bound resource
cost estimate to bracket the range of costs incurred from quieting portable air
compressors at each level.
Level One. Table 9-13 presents the estimated end user capital cost increases
for enforcing a Level One Noise Standard in 1976.
Table 9-13
TOTAL ESTIMATED FIRST YEAR INCREASED CAPITAL COSTS
FOR END USER INDUSTRIES-LEVEL ONE-1976
Portable Air Compressor
Power Source Type and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
TOTAL
Increased Capital Costs *
Lower Bound
$ 4,839
3,579
11,397
$19,815
Upper Bound
$ 5,113
3,809
12,092
$21,014
Note: * Capital costs equal the adjusted forecast volume (lower bound)
and baseline forecast (upper bound) multiplied by the increased
capital cost per unit.
9-19
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Table 9-14 presents estimated total annual cost increased for end user
industries after the adoption of a Level One standard in 1976.
Table 9-14
TOTAL ESTIMATED FIRST YEAR INCREASED
ANNUAL COSTS (IN THOUSANDS)
FOR END USER INDUSTRIES-LEVEL ONE-1976
Portable Air Compressor
Power Source Type and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
TOTAL
Increased Annual Costs
Lower Bound
968
716
2,280
$3, 964
Upper Bound
1,022
762
2,418
$4, 202
Note: (1) Annual total costs include depreciation, capital costs, trans-
portation cost, operating costs, and maintenance costs.
costs.
(2) Ten year, straight line depreciation of 10% per year is used.
(3) A return on investment or capital cost rate of 10% of the
capital investment is used.
(4) There are no increased transportation costs associated with
Level One.
(5) The analysis indicates that there will be only negligible in-
creases in operating costs.
(6) Maintenance costs associated with Level One are projected
to be negligible.
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From the data in the table it can be seen that the total estimated increased
annual costs for the first year of enforcement are estimated to be in the range
of $3. 9 to $4. 2 million.
Level Two. Increased end user capital cost estimates in the first year of
enforcement after adoption of a Level Two noise standard in 1978 is presented
in Table 9-15.
Table 9-15
TOTAL ESTIMATED FIRST YEAR INCREASED CAPITAL COSTS
(IN THOUSANDS) FOR END USER INDUS TRIES-LEVEL TWO-1978
Portable Air Compressor
Power Source Type and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
TOTAL
Increased Capital Costs *
Lower Bound
8,378
5,489
13,997
$27, 864
Upper Bound
11,749
7,454
15,718
$34,921
Note: * Capital costs equal the adjusted forecast volume (lower
bound) and the baseline forecast (upper bound) multiplied
by the increased capital cost per unit.
Estimated total annual cost increases in the first year of enforcement after
adoption of Level Two noise standard in 1978 are presented in the following
table (Table 9-16).
9-21
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Table 9-16
TOTAL ESTIMATED FIRST YEAR INCREASED ANNUAL COSTS
FOR END USER INDUSTRIES-LEV EL TWO-19 78
Portable Air Compressor
Power Source Type and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
TOTAL
Increased Annual Costs
Lower Bound
1,723
1,127
2,943
$5, 793
Upper Bound
2, 416
1, 538
3, 304
$7, 258
Notes: (1) Annual total costs include depreciation, capital costs, trans-
portation costs, operating costs, and maintenance costs.
(2) Ten year, straight line depreciation of 10% per year is used.
(3) A return on investment or capital cost rate of 10 percent
of the capital investment is used.
(4) An explanation of the method used to calculate the increased
transportation costs associated with Level Two appears in
Reference 8.
(5) The analysis indicate that there will be only negligible
increases in operating costs.
(6) Maintenance cost increased associated with Level Two are
projected to be minor.
From the data in the table it can be seen that the total estimated increased
annual costs for the first year of enforcement are estimated to be in the range
of $5.8 to $7.2 million.
100 Percent Quieted Population. Based on an extrapolation of the 1976 to
1978 portable air compressor population baseline, estimates were made using
a 2.2 percent annual growth rate to determine the estimated population of
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portable air compressors in 1990. It is estimated that using the 2.2 percent
annual growth rate figure that the population would be 140, 000 by 1990.
It has further been calculated that a Level One noise standard may result
in reducing the estimated 1990 portable air compressor population by about
5 percent. On this basis, it can be concluded that the Level One total 1990
population will be approximately 133, 000 units. A Level Two noise standard
may result in reducing the estimated 1990 population by 27.7 percent. Based
on that reduction, the Level Two total 1990 population would be approximately
101,000 units.
Table 9-17 summarizes the increased annual operating cost of a 100-percent
quieted portable air compressor in 1990.
Table 9-17
TOTAL ESTIMATED ANNUAL INCREASES IN COST (IN THOUSANDS)
FOR END USER INDUSTRIES BY LEVEL - 1990
Noise Standard
Level One
Level Two
Increased Annual Cost
Lower Bound
34.6
46.7
Upper Bound
36.6
61.3
Of significance, it should be noted that:
1. Estimated Level One annual increased costs range closely from $34. 6
to $36.6 million. Level Two cost estimates range more widely from
$46. 7 to $61. 3 million.
2. As the required noise emission level is reduced, the cost of quieting
increases. Although the total number of units at Level Two is less
than at Level One, estimated Level Two costs are increased over Level
One by over 59 percent for the upper bound estimate and slightly over
74 percent ofr the lower bound estimate.
9-23
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Summary
The analysis of the cost of the resources required to quiet portable
air compressors indicates that:
1. The capital costs associated with sound attenuation are significant.
Total portable air compressor sales were approximately $90 million
in 1972. First year capital costs are projected to be approximately
$19. 8 to $21 million for Level One and $27. 8 to $34. 9 million for
Level Two.
2. Total operational costs for a 100% quieted population will also be
significant. These operational costs are projected to be $34. 6 to
$36.6 million annually for Level One and $46. 7 to $61. 3 million
annually for Level Two.
Market Impact
The impact of promulgating noise emission levels for portable air com-
pressors on the market and industry as a whole was discussed in greater detail
in Section 4 of this project report. However, this discussion treats in a summary
form those impacts on the market that can be expected from the adoption of noise
control technology. Included in this summary are the impacts on upstream
component suppliers, downstream distributors, and end users.
Suppliers
General supplies to portable air compressor manufacturers will riot
be adversely affected by the adoption of noise control technology primarily
because most suppliers to the industry derive only a small portion of their
business from manufacturers of portable air compressors. The portable air
compressor industry, due to its relatively small size when compared to its
component suppliers, will not have an appreciable effect on them without regard
to the level established for the emission regulation. The component suppliers
to the industry are: (1) engine manufacturers, (2) muffler manufacturers,
(3) fan manufacturers, and (4) enclosure and vibration isolator manufacturers.
9-24
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Distribution
At Level One, channels of distribution and portable air compressor
operations are not expected to materially change due to the noise emis-
sion standards.
Level Two will not cause channels of distribution to change. However, it
will have a greater impact on distributor operations. Many distributors will
add other air source lines and competitive systems to their present product
lines. The portable air compressor sales mix will change in the lower capacity
models reflecting a shift toward more gasoline engine models.
End Users
It has been estimated that the increased costs to be incurred by portable
air compressor owners at Level One will be less than 0.1 percent of total
operating costs of end user industries. Therefore, little, if any, changes in
portable air compressor end user industries are expected at Level One.
Capital and operational cost increases at Level Two are significant. Some
end users having a requirement to work on or move material will purchase
alternative compressed air sources or competitive systems. Others will
switch to rentals as a method to fulfill their compressed air requirements.
There will be a tendency to extend portable air compressor life through pre-
ventive maintenance programs.
Manufacturers
This discussion presents additional impacts that are anticipated from the
adoption of noise standards on portable air compressor manufacturing
operations.
Level One. The analysis undertaken shows that there will be no need for
increased factory floor space. There will be minor investments required for
production equipment. It is not felt that employment will be significantly affected
because of (1) a slight reduction in employment due to decreased sales volume
and (2) the need to hire additional personnel to incorporate modifications in the
portable air compressors required by the Level One regulations.
9-25
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Level Two. The analysis of the impact of Level Two upon the manufacturers
is not as clear as would be desired due to the uncertainty that the manufacturers
themselves expressed as to what engineering, production, and employment
changes would be necessary to ensure that the recommended modification (con-
tained in Section 8) produces the level of quieting desired.
However, estimates have been made as to the requirements for increased
factory floor space within range from 10 to 50 percent. Increases in production
timewlll also be necessary. These estimates range from 15 to 35 percent.
The estimated 27. 7% decline in unit volume will have a definite impact on
the market. However, because manufacturers do not know the extent of the
engineering modifications that Level Two will necessitate, a quantitative analysis
of either employment increases or decreases cannot be made. However, a
general employment forecast can be made as follows:
1. Firms having plants primarily engaged in portable air compressor
production may be faced with sizable layoffs due to reduced unit
volume. An order of magnitude estimate of the extent of the employ-
ment decrease is ten to twenty-five percent.
2. Firms with plants in which portable air compressors represent a
moderate portion of total production may be able to transfer some
porduction workers to other functions, and only moderate employment
decline is anticipated. Some of these plants will be benefited by
increased sales of other air systems or hydraulic systems. An order
of magnitude estimate of the extent of employment decrease is five
percent to ten percent.
3. Firms with plants in which portable air compressor represent only a
small portion of total employment may be able to transfer all affected
production workers to other functions and no decline in employment is
anticipated.
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Foreign Trade
This discussion covers the impact of the adoption of noise standards on
export and import patterns for portable air compressors. Noise regulations do
not apply to export products but do apply to products imported for use in the
United States.
Exports
Domestic portable air compressor manufacturers will be able to export
quieted and unquieted products to foreign countries, depending on the competi-
tive requirements of the foreign market with respect to the noise regulations.
To the extent that some foreign markets require quiet compressors, domestic
manufacturers will be in an improved competitive position since they will have
made progress in the application of noise technology to their products under
the impetus of noise regulation.
Study inputs from portable air compressor manufacturers indicated that
no changes in export patterns were expected due to noise regulations.
Imports
Imports currently account for five to ten percent of total domestic portable
air compressor unit consumption. Imported portable air compressor prices
are generally competitive or lower than domestic manufacturer prices. However,
imports have not significantly penetrated the United State portable air compressor
market because of lack of effective distribution networks, poor product quality,
in some instances, poor service and parts delivery, and intensive competition
by domestic producers.
At Level One, quieted imported portable air compressors are not expected
to make significant inroads into the domestic market. The costs associated
with quieting, plus the import costs would be more than the costs incurred by
domestic producers to meet Level One.
At Level Two, significant inroads into the domestic market could be made
by foreign firms. The extent of their market penetration will depend upon the
lead time given to meet the Level Two noise standard and price increase required.
9-27
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Some foreign firms currently produce some models that have noise emission
levels at or below Level Two standards. It appears that if adequate lead time is
not allowed for domestic producers to engineer and manufacture portable air
compressors on a production basis, these foreign manufacturers may be pre-
sented a good opportunity to gain an effective distribution system in the United
States. If this occurs, and their products sell at a price less than the Level
Two domestic product, then their combined order of magnitude market penetra-
tion could range anywhere from 15 to 40 percent.
Estimates of what constitutes an adequate lead time vary, depending on
the source, from two to six years. Estimates of what constitutes a significant
price differential vary from 1 to 40 percent.
If adequate lead time is allowed and domestic manufacturers remain price
competitive at Level Two, no shifts in the domestic/import market share are
expected.
Balance of Trade
Based on the factors reviewed:
1. No material impact on the balance of trade is anticipated from setting
Level One.
2. No material impact on the balance of trade is anticipated from setting
Level Two if an adequate lead time is given and domestic producers
remain cost competitive.
3. A moderate impact on the balance of trade is anticipated from setting
Level Two if adequate lead time is not provided and domestic producers
cannot remain price competitive.
Individual Impacts
This discussion addresses differential impacts that may develop affecting
a single firm or set of firms.
9-28
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Small Portable Air Compressor Manufacturers
Small manufacturers may not have sufficient manpower and funds to allocate
to the larger and more costly development programs that will be required. How-
ever, at Level One, costs and quieting technology are not expected to create a
problem to which small manufacturers cannot adjust with adequate lead time.
At Level Two some of the smaller firms in weaker financial positions may
be forced out of the portable air compressor market. It has been estimated that
50 percent of the firms with under $5 million of sales, currently operating at
losses, or employing less than 100 persons in their portable air compressor
operations are likely to withdraw from the market. These firms collectively
account for less than ten percent of dollar sales. The exit of half of these
companies from the market would not cause a dramatic redistribution of market
share. However, it would cause a loss of jobs at the local level in this industry.
Firms Experienced in Noise Technology
Those firms having attained a degree of noise technology and currently having
quieted products on the market are much better prepared to meet the noise emission
levels suggested for study. This will give firms experienced in quieting technology
an advantage in the market for a limited period.
Distruptive Impacts
This discussion assesses the potential for disruptive economic impacts
due to the establishment of noise standards per se. It concerns real-world
impacts as opposed to impacts that are a change in a forecasted future. With
adequate lead time and appropriate planning, business management is able to
adjust its plans to reflect changing conditions and to avoid adverse impacts on
its operations. Through adjustments in planning future over-capacity, unemploy-
ment, and other adverse conditions are avoided.
Assessment
The adoption of the noise emission levels suggested for study will have the
following probable effects.
!• Level One - 1976. No disruptive impacts are indicated at this level.
Cost changes are from ten to twenty percent. However, volume changes
9-29
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are minor from baseline conditions. The portable air compressor
industry would be expected to continue its normal growth pattern with
a Level One noise standard. No unemployment would be anticipated.
2. Level Two - 1977. Adoption of a Level Two standard will result in
estimated higher costs reflected in substantial price increases (33.2
percent, 47.2 percent, and 20. 5 percent for gasoline, diesel below
501 cfm and diesel above 500 cfm units, respectively). It has been
estimated that this may result in an overall 27.7 percent decrease in
domestic portable air compressor demand. Portable air compressor
production shifts may occur in the small capacities to more gasoline
engine compressors. A shift may occur to alternative air sources
and competitive systems. Under Level Two, the growth pattern of
the portable air compressor industry may be curtailed. Some
unemployment can be anticipated. A January 1, 1978 enforcement
date for Level Two is considered inadequate lead time by many manu-
facturers. If this estimate is correct, enforcement of the Level Two
time frame is likely to permit foreign manufacturers to establish
distribution systems and significantly increase their penetration of
the domestic market.
Given the size of the portable air compressor industry, no significant
economic disruption will be caused the national or regional economy from these
changes. Some small unemployment (measured in tens) may occur in specific
communities.
SUMMAHY
In this section, the economic impact has been assessed based on technical
and cost estimates provided by EPA through its contract with BBN. A brief
summary of the results is presented as follows:
9-30
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1. Estimated compressor list prices may increase as shown below in
Table 9-18.
Table 9-18
SUMMARY OF ESTIMATED LIST PRICE INCREASES
Power Source Type and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
Average Price Increase
List Price Increase (%)
Level One
16.2
18.4
14.4
16.3
Level Two
33.2
47.2
20.5
33.6
The price increases will be passed on to end users.
2. Unit volume may be affected as indicated in Table 9-19.
Table 9-19
SUMMARY OF ESTIMATED FIRST YEAR UNIT REDUCTION
FROM BASELINE FORECAST
Power Source Type
and Capacity
Gasoline Engine, all cfm capacities
Diesel Engine, below 501 cfm
Diesel Engine, above 500 cfm
TOTAL
Unit Reduction
Level One (19V6)
358
148
121
6~2T
Level Two (1978)
2,100
742
244
3, 086
3.
Level One may result in an overall 4. 5 percent decline in unit volume.
Level Two may result in as much as an overall 25.0 percent decline in
unit volume.
The estimated cost of noise abatement for portable air compressors is
presented below in Table 9-20.
9-31
-------
Table 9-20
SUMMARY OF THE ESTIMATED RESOURCE COSTS (IN MILLIONS)
ASSOCIATED WITH NOISE ABATEMENT
Noise Standard
First Year of Enforcement
Capital Costs
Annual Costs
100% Quieted
Population
Level One - 1976
Lower Bound Estimates
Upper Bound Estimates
Level Two - 1978
Lower Bound Estimates
Upper Bound Estimates
$ 19.8
21.0
27.8
34.9
$3.9
4.2
5.8
7.2
$ 34.6
36.6
46.7
61.3
4. There will be little effect on upstream component suppliers. Distri-
butors and end users will be affected in that alternative air sources
and competitive systems will become a more important factor in working
on or moving material.
5. There will be no effect on factory operations at Level One. Level Two
may require more floor space and assembly time and possibly some
production line changes.
6. No unemployment is expected to occur due to Level One. Moderate
unemployment in isolated localities may occur is Level Two is adopted.
7. No changes in export patterns will occur because of noise regulations.
Import patterns are not expected to change due to Level One. Imports
may significantly penetrate the domestic market with a Level Two if
adequate lead times are not established and domestic manufacturers
cannot product a unit that is price-competitive with imported units.
8. If Level Two is adopted, some small manufacturers with weak
financial positions are likely to withdraw from the portable air com-
pressor market.
9-32
-------
9. There is a potential for disruptive impacts from adoption of a Level
Two noise standard. However, no significant impact will be transmitted
to the national or a regional economy.
9-33
-------
Section 10
EVALUATION OF PORTABLE AIR COMPRESSOR NOISE ON PUBLIC
HEALTH AND WELFARE OF THE U. S. POPULATION
Pursuant to the Noise Control Act of 1972, EPA has selected and published
noise measures believed to be most useful for describing environmental noise
and its effect on people, independent of the sources(s) of noise. In addition, in-
formation has also been published on the noise levels "requisite to protect the
health and welfare with an adequate margin of safety". The phrase "public health
and welfare" includes personal comfort and well being, as well as the absence
of clinical symptoms (e. g., hearing loss). Using information published in
References 1 and 2, an analysis has been conducted to assess the effects of the
proposed air compressor regulation on the public health and welfare of the
United States population.
The approach taken for the analysis was to first evaluate the effects of the
proposed air compressor regulation alone and then in combination with other
possible regulations for other pieces of construction equipment, since air com-
pressors are often operated with other equipment.
The methodology presented in Appendix B has been applied to the specific
case of construction noise to evaluate the potential effect of the portable air com-
pressor proposed noise on the public health and welfare. The basis of the
[21
analysis has been the model presented in EPA Report No. NTID 300.1. J
The analysis that follows considers construction associated with residential
and nonresidential buildings, city streets and public works that normally occur
in places where the population density is high. Heavy construction, such as high-
ways and civil works, has been omitted from the study since the bulk of this
activity generally occurs in thinly populated areas where the potential noise
effects on people are minor. In the framework of the analysis, construction is
viewed as a process that can be categorized according to the type of construc-
tion and the separate and distinct activity phases that occur.
10-1
-------
The basic unit of construction activity is the construction site. A construction
site exists in both time and space. Four different types of construction sites were
evaluated in the analysis:
1. Domestic housing and residential
2. Office Buildings, hotels, hospitals, schools, government buildings, in-
cluding highrise
3. Industrial, parking garage, religious monuments, amusement and
recreation, stores, service stations, but no highrise
4. Public works, municipal streets and sewers.
Construction activity is carried out in several discrete steps, each of which
has its own mix of equipment and attendant noise output. The phases of con-
struction studied were those of Reference 2. The data presented in Reference
2 have been adopted for the present analysis, since they provide all the necessary
Input for deriving the variation in noise output with time. Basically, the process
involved in deriving the noise history at each site consists of identifying the
equipment found at each site in each construction activity phase in terms of:
• The number of equipment types typically present at the site in a given
phase
• The length of duty cycle of each type of equipment.
• The average noise level of each equipment type during the construction
activity operation.
The original information given in Reference 2 has been reviewed and re-
vised to include data that has since become available. The revisions appear in
Table 10-1 a, b, c and d.
The usage factors presented in Table 10-1 were combined with the typical
number of hours, H, the equipment operated for a particular task to yield a
value of L for the site as measured 50 feet from the site during an average
10-2
-------
Table 10-l(a)
USAGE FACTORS OF EQUIPMENT IN DOMESTIC HOUSING CONSTRUCTION*
Equipment**
Construction Phase
tf
Air Compressor
Backhoe
Concrete Mixer
Concrete Pump
Concrete Vibrator
Crane, Derrick
Crane, Mobile
Dozer
Generator
Grader
Jack Hammer
Loader
Paver
Pile Driver
Pneumatic Tool
Pump
Rock Drill
Roller
Saw
Scraper
Shovel
Truck
[81]
[85]
[85]
[82]
[76]
[88]
[83]
[87]
[78]
[85]
[88]
[79]
[89]
[101]
[85]
[76]
[98]
[74]
[78]
[88]
[82]
[88]
S
CD
O
-
.02
-
-
-
_
-
.10
.4
.05
-
.2
-
-
-
-
-
-
-
.05
-
.04
T .
£
o
H
. 1
.2
-
-
-
-
-
. 1
-
-
-
. 1
-
-
-
. 1
.005
-
-
-
. 2
.1
TT\£*-r* CM
1
O
PM
_
-
.4
-
-
-
-
-
-
-
-
-
-
-
.04
.2
-
-
.04
-
-
+ o rh
a
*[j>
o
W
-
-
08
bO
.3
,3
m
a
CM
.25
.02
.16
rj
J-J 0)
O +*
ff 4J
faJD o ^
H cd ^
b ® 8*
D ?H R
73 O P*
— . **"* -? a cS
68.7
69.6
76.4
. 10
.1
.04
.04
-
.02
.01
.04
.025
.04
-
-
.04
.04(2)
. 01
-
.04
69.6
71.9
64.6
64.8
60.8
65.2
65.8
72.3
63.0
65.6
52.8
68.3
66.8
65.6
70.3
Hrs. at site
per site during work periods = 81. 6 dBA
eq (50')
24 24 40 80 40^= 208 hrs.
= 26 days
Total number of sites =514, 500 (Table X of reference 2)
* Numbers in parentheses represent average number of items in use, if
that number if greater than one. Blanks indicate zero or very rare
usage.
**Numbers in brackets [ ] represent average noise levels [dBAj at 50 ft.
10-3
-------
Table 10-l(b)
USAGE FACTORS OF EQUIPMENT IN NON RESIDENTIAL CONSTRUCTION*
($190K-4000K)
Equipment**
Construction Phase
[81]
[85]
[85]
[82]
[76]
[88]
[83]
[87]
[78]
[85]
[88]
[79]
[89]
[101]
[85]
[76]
[98]
[74]
[78]
[88]
[82]
[88]
12,500
bD
.a
rrt
$
r—t
U
-
.04
-
-
-
-
-
.16
.4(2)
.08
-
. 16
-
-
-
-
-
-
-
. 55
-
.16(2)
L
eq(50';
80
(Tables
g
rt
o
H
1.0(2)
. 16
-
-
-
-
-
.4
1.0(2)
-
. 1
.4
-
-
-
1.0(2)
.04
-
-
-
.4
.4
1
j j
1
g
\J
1.0(2)
.4
.4
.08
. 2
-
-
-
-
-
. 04
-
-
. 1
.04
1.0(2)
-
-
.04(3)
-
-
-
1
->->
o
0
w
1.0(2)
-
.4
.4
. 2
.16
.16(2)
-
-
-
.04
-
-
-
. 16(2)
.4
-
-
1.0(3)
-
-
-
•r-t
1
'3
•i— I
.4(2)
.04
.16
.08
.04
.04
.04(2)
.16
_
.02
.04
. 16
.1
_
.04(2)
-
.005
. 1
-
-
-
.16
per site during work periods =
320
X and
320
480
B-l of reference
160 £ =
2)
Ei
^
i :s
•^ o ^*
i| I
ST fn 0)
G) n*» i^.
,j 8, &
83.4
76.4
79.1
74.3
66.9
75.9
73.9
77.9
75.2
63.5
75.2
69.9
69.7
84.8
76.2
76.4
78.0
54.7
78.4
73.1
71.8
79.2
90. 9 dBA
1360 hrs.
170 days
Air Compressor
Backhoe
Concrete Mixer
Concrete Pump
Concrete Vibrator
Crane, Derrick
Crane, Mobile
Dozer
Generator
Grader
Jack Hammer
Loader
Paver
Pile Driver
Pneumatic Tool
Pump
Rock Drill
Roller
Saw
Scraper
Shovel
Truck
Hrs. at site
Total number of sites
* Numbers in parentheses represent average number of items if number
is greater than one. Blanks indicate zero or very rare usage.
** Numbers in brackets [ ] represent average noise levels [dBA] at 50 ft.
10-4
-------
Table 10-l(c)
USAGE FACTORS OF EQUIPMENT IN INDUSTRIAL CONSTRUCTION*
($30K-820K, no high-rise)
Equipment**
Construction Phase
Air Compressor
Backhoe
Concrete Mixer-
Concrete Pump
Concrete Vibrator
Crane, Derrick
Crane, Mobile
Dozer
Generator
Grader
Jack Hammer
Loader
Paver
Pile Driver
Pneumatic Tool
Pump
Rock Drill
Roller
Saw
Scraper
Shovel
Truck
Hrs. at site
Total Number of sites
JH
O
a
[81]
[85]
[85]
[82]
[76]
[88]
[83]
[87]
[78]
[85]
[88]
[79]
[89]
[101]
[85]
[76]
[98]
[74]
[78]
[88]
[82]
[88]
»
•1-4
%
JS
o
_
.04
-
-
-
-
-
.2
.4
.05
-
. 16
-
-
-
-
-
-
-
. 14
-
. 16(2)
L
'i«
K-
«
o
H
1.0
.16
-
-
-
-
-
.4
.4
-
. 1
.4
-
-
-
.4
.02
-
-
-
.4
.26(2)
per
3
*T"(
3
o
PM
.4
.4
.4
.05
.2
-
-
-
-
-
.04
-
-
.04
.04
1.0(2)
-
-
.04(2)
-
-
-
o
•r-l
O
w
.4
-
. 16
. 16
. 1
.04
.08
-
-
-
.04
-
-
-
.1(3)
.4
-
-
.1(2)
-
-
-
site during work
•1-4
,£3
03
3
fc
.4
.04
.16
.08
.04
.02
.04
.04
-
.02
.04
.04
.12
-
.04
-
.003
. 1
-
.08
.06
.16
periods
~ » S
- 03 S3
O rrt O
52- o
O* "fj
1-3 O- O
78.2
76.4
77.3
70.9
65.4
70.2
68.2
77.5
68.7
62.3
75.2
69.4
70.5
80.8
76.0
53.1
75.1
54.7
67.5
70.5
72. 1
78.5
= 87.8dBA
eq (50')
80
320
320 480 160 £ = 1360 hrs
170 days
50, 000 (Tables X and B-l of Reference 2)
* Numbers in parentheses represent average number of items in use, if that
number is greater than one. Blanks indicate zero or very rare usage.
** Numbers in brackets [ ] represent average noise levels [dBA] at 50 ft.
10-5
-------
Table 10-l(d)
USAGU FACTORS OF EQUIPMENT IN PUBLIC WORKS CONSTRUCTION*
(Municipal Streets and Sewers)
Equip mi-'it* :<
Air Compressor
Backhoe
Concrete Mixer
Concrete Pump
Concrete Vibrator
Crane, Derrick
Crane, Mobile
Dozer
Generator
Grader
Jack Hammer
Loader
Paver
Pile Driver
Pneumatic Tool
Pump
Rock Drill
Roller
Saw
Scraper
Shovel
Truck
bD
•1-1
0)
r-H
O
[81] 1.0
[85] .04
[85] -
[82] -
[76] -
[88] -
[83] -
[87] .3
[78] 1.0
[85] .08
[88] .5
[79] .3
[89] -
[101] -
[85] -
[76] -
[98] -
[74] -
[78] -
[88]
[82]
[88]
08
04
16(2)
Construction Phase
§
1
aS
o
W
1.0
.4
. 1
.4
.4
.5
.4
a
o
g
Pn
.4
es
o
a>
.4
. 16(2) .4(2)
04
,2
,4
.2
0.1
.04(2)
.4(2) 1.0(2)
.02
.01
.04(2)
. 2
.4 .04
.16 .4(2)
04
16
4
2
04
1
4(2)
5
04
08
2(2)
eq(50')
12
per site during work periods =
12 24 24 12 2 =
bD
1
;a
£
.4(2)
.16
. 16(2)
"~
-
. 16
.4
.08
.1(2)
. 16
-
.04
-
-
.5
-
.08
.04
. 16(2)
riods =
* s
t; 53
o **
III
•r1 On
M
-a £ a
*" r/) £*{
"a*
t-5 cL 0
79.0
74.4
80.7
73.8
69.7
79.6
74.9
74.1
80.7
71.6
81.4
72.6
75.7
82.6
67.4
63.4
78.2
71. 1
84.6
91. 1 dBA
Hrs. at site:
Total number of sites - 336, 600 (Table XIII of Reference 2)
84 hours
10 1/2 days
^Numbers in parentheses represent average number of items in use, if that
number is greater than one. Blanks indicate zero or very rare usage.
**Numbers in brackets [ ] represent average noise levels [dBA] at 50 ft.
10-6
-------
work period. For the purpose of this analysis, a construction site is viewed as
a complex source in which equipment is centered at 50 feet from an observer.
This consideration provides a model with which to establish a base set of data.
The L obtained using the model was converted to an L, for a 24-hour
eq dn
day and then converted to an annual L by adding 10 log (H/(8 x 365)). Thus,
each construction site was viewed as a complex noise source with a fixed annual
value of L, . The analysis was repeated for each type of site.
an
The human impact of construction noise was brought into the analysis by
use of the data presented in Reference 2 with regard to the number of construction
sites of various types in a number of geographical regions, as well as the density
of people in these geographical regions. The number of sites per year was
taken from Table 10 of Reference 2, and the population density data was taken
from Table 9 of the same reference. For the office building category, the
transfer of people from the suburbs to the central city during the average work-
ing day was considered by adjusting the population data, consistent with the
model presented in Reference 2, which is summarized in Table XI of the Refer-
ence. This adjustment was necessary to account for the fact that most construc-
tion in cities occurs during the working day. Thus, population estimates were
obtained for 20 different cases corresponding to the four construction types
(residential buildings, non-residentials, municipal streets and public works)
and five categories of regions:
1. Large high-density central city
2. Large low-density central city
3. Other Standard Metropolitan Statistical Areas central cities
4. Urban fringe
5. Metropolitan areas outside the urban fringe.
Two models were used for the propagation of site noise into the community.
In residential areas and other lightly built up areas, noise was assumed to be
10-7
-------
attenuated at the rate of 6 dB per doubling of distance. Accordingly, around
each site there exists a series of annul! each of which represent successive 3 dB
areas of greater attenuation. A mean noise level L, (Annual L, ) was associated
dn dn
with each annulus as well as the area in square miles. The latter figure when
multiplied by the population density typical of the region yielded the number of
people, P, on the average, living within that annulus. It was assumed that on
the average, only half of these people were affected by the noise because it is
reasoned that only half of the rooms in structure in proximity to the site face
the site. This assumption appears reasonable but must be recognized as some-
what arbitrary.
In the case of office building category, a different model was considered.
For this situation, it was assumed that noise confined in a builtup area is at-
tenuated by only 3 dB per doubling of distance due to the canyon effect for the
first 400 feet and then attenuated by 6 dB beyond the 400 feet, since at that point
noise is free to decrease by classical spherical divergence. Further, it was
assumed that only 25% of the people in each annulus were affected by the con-
struction noise since in most office buildings not all the rooms have outside ex-
posure. This assumption appears reasonable, but it is somewhat arbitrary.
In the computation of the fractional impact (FI) associated with each annulus
around the construction site for office buildings and for industrial sites, com-
putations were performed relative to an exterior L, of 65 dB rather than the
dn
55 dB assumed for residential areas and public work areas. The rationale for
this assumption was that in office buildings adjoining construction sites,, windows
are normally closed rather than open, which increases the noise reduction be-
tween outside and inside from 15 dB to 25 dB (Reference 30). Thus, the additional
10 dB.
From knowledge of the various fractional impacts and number of people as-
sociated with each annulus, the equivalent population impacted at 100% for each
annulus was obtained and then summed to obtain the total impact (P ). *
eq
10-8
-------
From knowledge of the various fractional impacts and number of people
associated with each annulus, the equivalent population impacted of 100% for
each annulus was obtained and then summed to obtain the total impact (P ). *
Computations were performed for several conditions, with a baseline
condition established using the noise levels of all construction site equipment
listed in Table 10-1. Also computed were conditions in which portable air
compressors were reduced to levels of 76 dBA, 73 dBA, 70 dBA, and 65 dBA
at seven meters from the compressor housing. Since new truck noise regula-
tions currently being formulated will, in time, cause lower truck noise levels
at the construction site, the effect of the combined reduction of portable air
compressors and new truck noise were additionally evaluated. The effect of
reducing portable air compressor and new truck noise levels are summarized
in terms of L, and P in Table 10-2. The effects of the change on the
dn eq
United States population are summarized in terms of P in Table 10-3.
eq
Figures 10-1 and 10-2 have been prepared from the data of Table 10-3 to
better show the impact of reducing new portable air compressor and new truck
noise levels.
Figure 10-1 shows that for portable air compressors, noise reduction at
the construction site, only, a sizable (approximately 11%) impact reduction is
achieved for portable air compressor noise reduction to 76 dBA at 7 meters,
while little (approximately 1% additional relief is obtained for further noise
reduction to 65 dBA at 7 meters.
*P is numerically equal to the equivalent number of people which have a
frac'fconal impact equal to unity (100% impacted). See Appendix B for further
details.
10-9
-------
bO
0
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10-10
-------
Table 10-3
THE EFFECT OF CHANGE ON THE UNITED STATES POPULATION
DUE TO THE PROPOSED PORTABLE AIR COMPRESSOR
AND NEW TRUCK NOISE LEVELS
Baseline date, 1974
Only Air Compressors Reduced
a) 72 dBA @ 50'
b) 69 dBA@ 50'
c) 66 dBA @ 50'
d) 61 dBA@ 50'
date, 1977: Trucks reduced 83 dBA
a) Air Comp @ 72 dBA @ 50'
b) Air Comp @ 69 dBA @ 50'
date, 1983: Trucks reduced 75 dBA
a) Air Comp @ present levels
b) Air Comp @ 72 dBA
@ 69 dBA
@ 66 dBA
@ 61 dBA
Baseline date, 1983
Trucks at 75 dBA @ 50'
a) Air Comp @ 72 dBA
@ 69 dBA
@ 66 dBA
@ 61 dBA
P
eq
1,042,000
927,484
919,635
915,670
912,936
730,423
721,408
696,790
569,554
562,501
558,903
556,033
696, 790
569,554
562,501
558,903
556,033
Percent
Reduction
0
10.99
11.74
12.12
12.39
29.90
30.76
33.13
45. 34
46.02
46.36
46.64
0
18.26
19. 27
19.78
20.20
10-11
-------
90
85
80
8
u
I
o
-------
In view of the results of Figure 10-1, Table 10-4 shows that construction
site noise impact relief, after portable air compressors are reduced to 76 dBA
at 7 meters, is obtained as the result of new truck noise reductions. Specifically,
shown by the data is:
1. When truck noise at the construction site is reduced to 83 dBA, the
percent impact reduction of construction site noise increases to
approximately 30%. This represents an approximate 19% additional
(over the compressor reduction alone case) impact relief.
2. When truck noise at the construction site is reduced to 75 dBA, the
percent impact reduction of construction site noise increases to
approximately 45%. This represents an approximate 34% additional
(over the compressor reduction alone case) impact relief.
The results of the public health and welfare study showed that portable air
compressor noise reduction to an average of 76 dBA at 7 meters produces a
significant and desirable impact relief. Table 10-4 has been prepared to show
the contribution of portable air compressor noise to total construction site
noise for portable air compressor reduced to 76 dBA (from a current average
level of 88 dBA at 7 meters). Also shown in the table, for comparison, is the
contribution to construction site by current compressor noise levels. Shown
by the data of Table 10-5 is that when portable air compressors are reduced to
76 dBA, the percent contribution to the construction site is reduced approximately
one percent, down from 17.8 percent in the worst present case. This decreases
the importance of portable air compressor as a source of acoustic energy,
from the 2nd noisiest source after trucks at present to the 16th noisiest piece
of equipment comprising the hardware mix at a typical construction site.
10-13
-------
Table 10-4
EFFECT ON THE UNITED STATES PUBLIC DUE TO
PORTABLE AIR COMPRESSOR AND TRUCK NOISE
REDUCTIONS TO VARIOUS LEVELS OVER TIME
Noise Level dB A
Portable Air
Compressor
88
76
76
76
Trucks
88
88
83
75
Percent -Impact Reduction
Of Construction Site
Noise
0
11
30
45
10-14
-------
Table 10-5
CONTRIBUTION OF PORTABLE AIR COMPRESSSOR NOISE
TO CONSTRUCTION SITE NOISE
Site
Residential
Public Works
Industrial
Non -Residential
Percent of Site Noise
Compressor
Noise
at 88 dBA*
5.0
6.1
10.7
17.8
Compressor
Noise
at 76 dBA**
1.0
1.0
1.0
1.0
Rank at Site
Compressor
Noise
at 88 dBA*
7th
7th
3rd
2nd
Compressor
Noise
at 76 dBA**
16th
16th
17th
17th
* Current average level at 7 meters of all compressors.
** Proposed average level at 7 meters.
10-15
-------
Section 11
ENFORCEMENT
Enforcement of new product noise emission standards applicable to new
portable air compressors may be accomplished through:
• Certification or production verification testing of compressor config-
urations.
• Assembly line testing using continuous testing (sample testing or 100%
testing).
• Selective enforcement auditing of production compressors and in-use
compliance programs.
The predominant portion of any certification or production verification
testing and assembly line compressor testing can be carried out by the manu-
facturer and audited or confirmed by EPA personnel as necessary.
Any test used for certification or production verification testing and any
test used for assembly line testing of production compressors should be the
same test or else should be correlative so that compliance may be accurately
determined. A measurement methodology that can be used both for certification
or production verification testing and any assembly line testing is a modified
version of the CAGI/PNEUROP test code.
CERTIFICATION
Certification is the testing of selected prototype products by a manufacturer
or by EPA to determine whether the products conform to a standard. Certifica-
tion serves the purpose of verifying that a manufacturer has the technology in
hand and, when required, it may be used to verify that the applied technology
will last for some period of use.
Certification may involve the testing of every configuration of a manufac-
turer's production to verify whether each conforms, or configurations may be
11-1
-------
grouped into categories having similar emission characteristics and so that
only selected configurations are tested. The configurations tested are then
considered representative of the other untested configurations in a category.
The concept of certification has associated with it the issue of approval
certificates by EPA after a manufacturer has demonstrated conformity through
testing.
Because certification normally deals with a few prototype models, it
does not give any indication of the conformance to standards of the manufacturer's
product. The ability of a manufacturer to apply the technology to a prototype
model does not necessarily mean that actual production line models will also
conform. Verification that production models conform can only be made by
actual testing of production models.
PRODUCT VERIFICATION
Production verification is the testing of selected pilot line (first production
models) by a manufacturer or by EPA to verify whether a manufacturer has
the technology in hand and is capable of applying the technology in a manufac-
turing process. The tested pilot line models (or first production models) must
conform with the standard prior to any distribution of that model into commerce.
Production verification does not involve any formal EPA approval or
issuance of certificates subsequent to manufacturer testing, nor is any extensive
testing required of EPA. Any regulations would require that prior to distribu-
tion into commerce of any manufacturer configuration, as defined within the
regulations, the configuration must undergo production verification. A com-
pressor model would be considered to have been production-verified after the
manufacturer has shown, based on the application of the noise measurement
tests, that a configuration or configurations of that model conform to the
standard. Production verification testing of all configurations produced by a
manufacturer may not be required when a manufacturer can establish that the
11-2
-------
noise levels of some configurations within a model are consistently higher than
others or are always representative of other configurations. In such a case, the
higher emitter would be the only configuration requiring verification. Manufac-
turers must reverify whenever they implement engineering changes to their
prorhirts after initial verification that are likely to adversely affect noise
emissions. Additionally, further testing on some continuing or other periodic
basis or production line products will still be necessary to assure, with some
confidence, that all products being manufactured conform to the standards
prior to being distributed into commerce.
Production verification provides EPA with confidence that production
models will conform to the standards and limits the possibility that nonconform-
ing compressors will be distributed in commerce because initial testing is
performed on pilot line or first production, models. Because the possibility
still exists that subsequent models may not conform, assembly line compressor
testing should be made a part of any enforcement strategy, to determine whether
production compressors continue to actually conform to the standard.
ASSEMBLY LINE TESTING
Assembly line testing of a production compressor is a process by which
compressors, as they are completed on the assembly line, are tested to deter-
mine whether they conform to applicable standards. This determination as to
whether production compressors comply with the standard can be made by the
use of either continuous 100% testing of newly assembly compressors or by
testing of representative samples of newly produced compressors and drawing
inferences with regard to the conformity with the standard of other newly
assembled compressors. In the case of the production of nominally identical
compressor configurations exhibiting the same or similar noise emission char-
acteristics through the application of the same or similar noise attenuation tech-
nology, the use of sample testing is a realistic way of determining compliance
by other untested compressors produced by a manufacturer.
11-3
-------
Continuous, 100-Percent Testing
In the absence of a short inexpensive test, 100-percent testing can be
costly and time consuming and in most cases unnecessary in the absence of
some justification to the contrary since sample testing can yield the desired
result. At this time, 100-percent testing is not proposed as a primary enforce-
ment tool: however, 100-percent testing may be required should a manufacturer
be discovered to be producing compressors in violation of the regulation.
Sample Testing
Sample testing involves the testing of a percentage of compressors on some
continuous basis, the auditing of production line compressors on some random
basis, or for specific cause. An auditing strategy would enable EPA to deter-
mine if production compressors meet any promulgated emission standards and
would provide a deterrent to the distribution in commerce of nonconforming
products. An auditing strategy involves the random testing of a representative
number of production compressors. Because the number of compressors tested
under an auditing strategy is nominal, the cost and effort associated with
implementation of such a strategy for a conforming manufacturer is only a
fraction of the cost of a program involving continuous testing because fewer
compressors are involved.
Any sampling strategy adopted by EPA would not attempt to impose a quality
control or quality assurance scheme upon a manufacturer but would merely
audit the conformity of his products and would provide a deterrent to the dis-
tribution in commerce of non-conforming products.
ENFORCEMENT ACTION
The prohibitions in the Act would be violated when:
• The manufacturer fails to properly certify or verify the conformance
of production compressors.
11-4
-------
• Where it is determined on the basis of assembly line testing or other
information that nonconforming production compressors are knowingly
being distributed into commerce.
• When the manufacturer fails to comply with an Administrator's order
specifying appropriate relief when nonconformity is determined.
REMEDIES
In addition to the criminal penalties associated with violations of the pro-
hibitions of the Act, which include fines and imprisonment, the Administrator
has the option of issuing an order specifying such relief as he determines
necessary to protect the public health and welfare. Such an order could include
the requirement that a manufacturer recall products distributed into commerce
not in conformity with the regulations and that a manufacturer effect any remedies
whether or not the manufacturer had knowledge of the nonconformity. Such
recall orders would be issued in situations in which assembly line testing
demonstrated that compressors of a particular configuration has been distributed
into commerce not in conformity with the applicable emission standards.
LABELING
Any enforcement strategies should be accompanied by the requirement for
labeling of products being distributed into commerce. The label will provide
notice to a buyer and user that the product is sold in conformity with applicable
regulations, that the compressor possesses noise attenuation devices, and that
such items should not be removed or rendered inoperative. The label should
also indicate the associated liability for such removal or rendering inoperative.
IN-USE COMPLIANCE
If the goal of protecting the public health and welfare is to be fully achieved,
the noise levels of compressors must not degrade above the standards prescribed
for assembly line compressors. The standards should therefore extend over
11-5
-------
the life of the products, as authorized by the Act. Several compliance strategies
can be used to ensure the maintenance of standards. The manufacturer is
required (by Section 6 (d)(l)) to warrant for the life of the compressor that it
conformed to standards at the time of initial sale. Recall is an appropriate
remedy (under Section ll(d)(l)) to require the manufacturer to remedy a class
of compressors that fails to conform while in actual use, despite proper main-
tenance and operation. The tampering with noise emission control devices and
elements of design is prohibited by Section 19(a)(2). Finally, the manufacturer
can be required (by Section 6(c)(l)) to provide instructions to purchasers
specifying the maintenance, use, and repair to keep the compressor within
standards.
11-6
-------
Section 12
ENVIRONMENTAL EFFECTS OF PROPOSED REGULATIONS ON
PORTABLE AIR COMPRESSORS
IMPACT RELATED TO ACOUSTICAL ENVIRONMENT
The proposed regulations will immediately stop the noise emitted by portable
air compressors from increasing and will limit their output to a level that will
reduce the number of people impacted by construction site noise by 114,000
(approximately). When reviewed in concert with new truck noise regulations,
the number of people relieved of impact will be 474, 000 (approximately). These
regulations are a first step in a comprehensive noise abatement effect aimed
at reducing the total environmental noise to which the population is subjected.
The composite impact of all Federal noise emission regulations will be aimed
at a level of environmental noise consistent with protecting human health and
welfare.
Studies have been conducted to estimate the reduction in noise levels and the
number of people who will benefit as a result of noise.
IMPACT RELATED TO LAND
Portable air compressor regulations will have no adverse effects relative
to land.
IMPACT RELATED TO WATER
Portable air compressor regulations will have no adverse effects on water
quality or supply.
IMPACT RELATED TO AIR
These regulations, when promulgated, will have only a slight impact on
air quality.
One of the engineering methods that will be utilized to quiet portable air
compressors is the installation of a more efficient muffler to reduce noise
12-1
-------
emissions. This will cause an increase in the back pressure and will reduce the
efficiency of the power source from 1 to 9%. Sources differ concerning the
increase in back pressure and resulting increased fuel consumption. Additionally,
technology studies have been done that indicating that with the appropriate
reengineering of portable air compressors to enable them to comply with the
noise emission regulations, fuel economy and efficiency will improve rather
than deteriorate.
There also exists a possibility of market shifts from gasoline-powered to
dies el-powered portable air compressors, which depends to a large extent upon
the elasticity factors discussed in Section 9. If these shifts occur in favor of
diesel-powered compressors, total air emissions will be substantially reduced.
There also exists the possibility of a reduction of total unit volume after
promulgation of the regulation. This may amount to as much as 27% of the
total unit volume projected depending upon the regulatory level chosen. If this
reduction occurs, then there will be a corresponding decrease in pollutants
emitted.
At this time, based on the interrelationship of: (1) potential increase in
fuel consumption, (2) elasticity of the market, and (3) potential total unit volume
reduction, the possibility of the portable air compressors having an adverse
effect on air quality is negligible.
12-2
-------
REFERENCES
1. "Information on Levels of Environmental Noise Requisite to Protect Public
Health and Welfare with an Adequate Margin of Safety, " Environmental
Protection Agency, 550/9-74-004, March 1974.
2. "Noise from Construction Equipment and Operations, Building Equipment
and Home Appliances, " Environmental Protection Agency NTID 300.1,
December 1971.
3. "Report to the President and Congress on Noise," 92d Congress, 2d Session,
92-63, February 1972.
4. Patterson, W.N., et al, "Specialty Construction Trucks: Noise and Cost
of Abatement," Bolt Beranek and Newman, Report No. 2566a, September
1973.
5. Freeze, T.W., et_al, "Portable Air Compressor: The Costs, Benefits
and Penalties of Reducing Their Noise, " EPA Contract No. 68-01-1539,
Bolt Beranek and Newman, Report No. 2566c, March 1, 1974.
6. Patterson, W. N., et al, "Portable Air Compressor Noise," Bolt Beranek
and Newman, Report No. 2795a, March 29, 1974.
7. Patterson, W. N., et al, "Portable Air Compressor Noise: Diagnosis and
Control," Bolt Beranek and Newman, Report No. 2795b, March 29, 1974.
8. Kearney, A. T., "A Study to Determine the Economic Impact of Noise
Emission Standards in the Construction Equipment Industry: Portable Air
Compressor Report."
9. Steele, S. and the Noise Information Program, "A Study of Local and State
Laws for the Noise of Construction Equipment," EPA Contract No. 68-01-
2229, Informatics, Inc., Rockville, Maryland, May 1, 1974.
10. The Noise Information Program, "Foreign Regulations for Construction
Equipment: A Status Report," EPA Contract No. 68-01-1894, Informatics,
Inc., Rockville, Maryland, March 25, 1974.
11. Holmer, C. I., "Measurement Methodology and Supporting Documentation
for Portable Air Compressors," National Bureau of Standards, Washington,
D. C., May 1974.
12. "Identification of Products as Major Sources of Noise," Federal Register,
Vol. 39, No. 121, June 2, 1974.
R-l
-------
13. "Standards on Noise Measurement, Rating Schemes, and Definitions: A
Compilation, " National Bureau of Standards, Washington, D. C., Publica-
tion 386, November 1973.
14. "Exterior Sound Level Measurement Procedure for Powered Mobile Con-
struction Equipment, " Proposed SAE Recommended Practice x588.
15. "Construction Site Sound Level Measurements," Proposed SAE Recommended
Practice.
16. "CAGI-PNEUROP Test code for the Measurement of Sound from Pneumatic
Equipment," ANSI S5.1-1972, 1969.
17. Peterson, A.P.G. and Gross, Jr., E. E., Handbook of Noise Measurement,
General Radio Co., 1972.
18. Griffiths, Lt. Col., J. D., "The Design of a Low Cost Sound Level Meter, "
USAFA TR-74-6, EPA 550/9-74-008, April 1974.
19. Francois, P., and Fleury, M., "Noise Measurement on Mobile Compress-
ors for Construction Sites, " Cour, de la Norm., No. 220-VII-VIII: 467-474
(in French), 1971.
20. Oncley, P. B., "Correction Procedure for Outdoor Noise Measurement,"
Inter-Noise 72 Proceedings, Washington, D. C., 1972.
21. Bettis, R. A., and Sexton, M. Z., "The Effect of Test Site Topography in
Vehicle Noise Measurement, " presented at the 85th Meeting of the
Acoustical Society or America, Boston, Mass., 1973.
22. Anderson, G. S., Miller, R. L., and Schwartz, R. M., "1972 Noise Levels
and Noise Models for Urban Truck Traffic: West Side Highway Project,"
Bolt Beranek and Newman Report No. 2519A, 1973.
23. Wiener, F. M., Malme, C. I., and Gogos, C.M., "Sound Propagation in
Urban Areas, " Journal of the Acoustical Society of America, 37: 739-747,
1965.
24. Kurze, U. J., and Anderson G.S., "Sound Attenuation by Barriers, " App.
A CPUS t., 4: 35-53, 1971.
25. Kessler, F. M., "Portable Compressor Noise Reduction-Final Report, "
Ingersall Rand Research, Inc., TND-362, August 1968.
26. Hinck, D. C. and McGahan, W. A., "Sound Reduction of Large Portable Air
Compressors," Ingersall Rand Research Inc.
27. Heinrich Flottman, K. G., letter to Informatics, Februarys, 1974.
R-2
-------
28. "Public Health and Welfare Criteria for Noise, " Environmental Protection
Agency Report 550/9-73-002, July 1973.
29. "Standard for the Calculation of the Articulation Index, " ANSI S3. 5-1969.
30. "House Noise - Reduction Measurements for Use in Studies of Aircraft
Flyover Noise," Society of Automotive Engineers, Inc., AIR 1081,
October 1971.
31. "Construction Noise Survey, " Bureau of Noise Control, New York Depart-
ment of Environmental Conservation, April 1974.
R-3
-------
Appendix A
DOCKET ANALYSIS
-------
LIST OF TABLES
TABLE TITLE PAGE
A-l Summary Index of Docket Responses A-2/3/4
A-2 CAGI Suggested Classification of Compressors A-5
A-3 Noise Levels of P. K. Lindsay Compressors A-7
Sound Level Readings in dBA
A-4 Range of Noise Levels of Compressors A-8
A-5 Portable Air Compressor Noise Levels, dBA A-10
A-6 Estimated Average Costs A-ll
A-7 International and Municipal Permissible Sound A-15
Levels and Compressors
-------
Appendix A
DOCKET ANALYSIS
On February 27, 1974, an Advance Notice of Proposed Rule Making (ANPRM)
inviting public participation in the development of a regulation for new portable
air compressors, which EPA might establish under Section 6 of the Noise Control
Act, was published in the Federal Register. There were ten submissions to the
ANPRM docket, four of which required no response as the commenter either mis-
interpreted the purpose of the ANPRM, requested an extension of time to submit
comments, or provided no information. The remaining entries, with the excep-
tion of that submitted by Richard H. Gimer (the Washington Counsel for the Com-
pressed Air and Gas Institute, whose members manufacture approximately 85%
of the air compressors sold in the United States), are not specifically addressed
to the 23 areas of information solicited in the ANPRM.
Insofar as possible, an effort has been made in analyzing the docket to dis-
tinguish between information and issues contained in the responses. The attached
docket analysis is organized as follows:
1. Summary Index - (citing specific references to the docket entry in the
Information and Issues Section)
2. Information Section (pages 1-19)
3. Issues Section (pages 20 - 36)
Docket entries are available for public inspection at the Office of Noise
Abatement and Control, Environmental Protection Agency, 1921 Jefferson
Davis Highway, Arlington, Virginia 20460.
INFORMATION CONTAINED IN DOCKET
Composition of Industry and Conditions of Product Use
Manufacturer Data (ANPRM #15)
P.K. Lindsey stated that while not one of the larger U.S. manufacturers,
A-l
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the Company's 1973 sales exceeded $2 million. The Company manufactures air-
cooled compressors of their own design and performs the machining and fabrica-
tion of the compressors, chassis, air tanks and housing in their own plant.
Gimer stated that members of the Compressed Air and Gas Institute's
Portable Compressor Air Section manufacture approximately 85% of the compres-
sors sold in the United States. The twelve members of this national trade asso-
ciation representing portable air compressor manufacturers are Atlas Copco,
Inc.; Chicago Pneumatic Tool Co.; Davey Compressor Co.; Gardner-Denver
Co. (Quincy Division); Gordon Smith & Co., Inc.; Ingersoll-Rand Co.; the
Jaeger Machine Co.; Joy Manufacturing Co.; Le Hoi Division—Dresser Industries,
Inc.; Quincy Compressor Division, Colt Industries Operating Corp.; Schramm,
Inc.; and Worthington-CEI, Inc.
Recommended Methods for Classifying Portable Air Compressors
(ANPRM #13)
Gimer commented that portable air compressors have historically been
classified by power source (diesel or gas) and by output measured in cfm.
Typical catagories are noted in Table A-2.
Table A-2
CAGI SUGGESTED CLASSIFICATION OF COMPRESSORS
Gas Powered Machine (2)
75-124 CFM
125-250 CFM
Diesel Powered Machines (4)
125-249 CFM 600-899 CFM
250-599 CFM 900 and over CFM
Number and Type of^Portable Air Compressors In-Service and Sold
(ANPRM #9)
Gimer submitted the following data compiled by the U. S. Department of
Commerce, CAGI and EPA contractors:
A-5
-------
• For the seven-year period 1966-1972, approximately 72,000 portable
air compressors were shipped (approximately 51, 000 were gasoline
engine powered, the remainder were diesel powered).
• Total sales during each of seven years ranged between 9,600 and
12,300 units.
• Approximate annual dollar value of shipments: 1970—61. 5 million;
1971—64.2 million; 1972—78.1 million.
The City of New York commented that it is estimated in New York City alone
there are approximately 5,000 air compressors available for use.
Portable Air Compressor Typical Duty Cycles (ANPRM #12)
Gimer pointed out that a high percentage of portable compressors are used
for less than one day in any particular location and submitted following estimates
on duty cycles:
• On the average, portable air compressors can be expected to work a
normal cycle of 60 to 75% on full load requirement and 20 to 40% on a
no-load requirement;
• Smaller portable units (up to 501 CFM) normally accumulate an average
of 1, 000 operating hours per year and larger units (over 500 CFM)
1, 000 to 1, 500 operating hours per year.
Types of Activities in Which Portable Air Compressors are Used,, Number
Used at One Time and Contribution to Total Noise of These Activities
(ANPRM #16 and #17)
Gimer commented that, in most instances, portable air compressors are
used to power other devices that in turn perform a particular work application.
Depending upon the size of the unit, the task to be accomplished, and the nature
of the job site, anywhere from one to twelve portable air compressors might be
utilized in a single location at one time. If a job situation required three or
more portable air compressors, they would probably be widely dispersed.
A-6
-------
Gimer further stated that, in most cases, the equipment powered by the
compressor or the nature of the work itself being performed with that equipment
is noisier than the compressor itself. This point was also alluded to by World
Construction and Ingersoll-Rand.
Current Noise Levels, Abatement Techniques and Their Effects
Current Noise Levels of In-Use and Newly Manufactured Foreign and
Domestic Portable Air Compressors (ANPRM #1)
P. K. Lindsay submitted the following chart (Table A-3) of noise levels
produced by current production units of their eight compressor models.
__ Table A-3
NOISE LEVELS OF P. K. LINDSAY COMPRESSORS
SOUND LEVEL READINGS IN dBA
COMPRESSOR
MODEL
15-HU
25 -HU
T-40HA
55-H
80-H
125-H
150-A
175-D
1 meter
89
98
95
94
96
98
99
100
5 feet
87
88
93
92
93
95
96
97
7 meter
75
77
81
79
81
82
84
85
50 feet
68
71
75
t 73
75
76
78
79
Tests were taken on current production units with standard engine mufflers.
A-7
-------
These readings are in decibels on the "A" weighting network scale and are
the arithmetic average of four readings at the compass point for each distance
from the compressor unit. Compressors are operating at full load (100 psig)
and the air is discharged to atmosphere beyond the test area.
Gimer submitted the following table (Table A-4) showing a range of noise
emissions on currently available domestic and foreign produced portable air
compressors for standard machines and silenced machines.
Table A-4
RANGE OF NOISE LEVELS OF COMPRESSORS (supplied by CAGI)
Standard Machines
82-250 CFM
92
80
. 5 dBA to 105 dB A at 1 meter
. 5 dBA to 92 dBA at 7 meters
251-1200 CFM
97
82
. 1 dBA to 112 dBA at
dBA to 103 dBA at 7
1 meter
meters
Silenced Machines
82-250 CFM
82
70
dBA to 104 dBA at 1 meter
dBA to 88 dBA at 7 meters
251-1200 CFM
82
70
dBA to 104. 5 dBA at 1 meter
dBA to 93 dBA at 7 meters
This data was collected on a confidential basis by the Compressed Air and
Gas Institute over the past two years using the CAGI-PNEUROP test cost
codified as a national consensus standard and an international standard in
ANSI S. 1-1971 and ISO 2151, respectively. Gimer placed two qualifications on
the analysis of this data.
1. The noise emission data reflects side emission measurements only,
and the precise impact on the dBA rating of any given compressor of
factoring in a measurement of upward radiating noise (under considera-
A-8
-------
tion by the appropriate ISO committees) cannot be known. Gimer
pointed out that tests which have been made using various proposed
methods for measuring upward radiated noise indicate that the
addition of a top-level measurement will change the dBA rating for
most compressors currently available; and
2. The data does not reflect the ability of the entire industry to meet
any particular emission level. Based upon information available to
CAGI the dBA rating of the quietest compressor available on the
market is several decibels below that which the industry as a whole
is currently capable of producing.
Currently Available Noise Abatement Technology (ANPRM #2)
Gimer commented that the major sources of noise from portable air com-
pressors are the areas of engine exhaust, cooling fan, air intakes, and mis-
cellaneous mechanical structure noises arising from the workings of the engine
and compressor air-end, withe the engine itself being the primary noise
source. Current noise-abatement technology focuses on enclosing and muffling
these engine/compressor operating components. This is currently best
accomplished by the application of large and often, expensive mufflers to the
engine exhaust; complete enclosure of all working mechanisms with acoustically-
lined air-tight housings; and attenuation of the cooling system fan-noise through
acoustically treated airduct systems. The acoustical attenuation materials
used to line the housing and cooling airducts are usually fiberglass or plastic-
based foam materials. The basic silencing technology utilized by foreign and
domestic manufacturers is the same.
The City of New York stated that air compressors are presently available as
shelf items that can provide reductions in noise levels by as much as 80% of cost
over conventional units of approximately 9%.
A-9
-------
Additional Noise Reduction Technology and Associated Costs (ANPRM /M
and #5)
Gimer stated that foreign and domestic individual compressor manufacturers
are currently utilizing all of the known technology to reduce noise emission levels
of their equipment. These efforts do not lead to uniform results due to the
firm's differing capabilities. Silencing a compressor adds to its cost and thus
to the manufacturer's ability to sell the end product. Gimer commented that
these costs can be expected to rise significantly as the noise emission level to
be achieved is reduced which he asserted will be shown through data being
collected under contract to EPA.
Pointing out that the sound emissions are a recognized competitive aspect
in the manufacture, promotion and sale of portable air compressors today,
Gimer stated that in the opinion of CAGI, market forces are: (1) causing a
high degree of individual firm utilization of currently available silencing
technology; and (2) encouraging intensive research efforts aimed at further
noise reduction.
Ingersoll-Rand took issue with the findings and statements contained in
EPS'a draft contractor reports. The Company submitted the following tables
reflecting noise level of portable air compressors and cost to achieve the
noise levels in lieu of those submitted by Bolt Beranek & Newman.
Table A-5
PORTABLE AIR COMPRESSOR NOISE LEVELS, dBA*
(provided by Ingersoll-Rand)
Level
Limit
Gasoline
Driven
75-249 CFM
Level 1 (3)
Level 2(4)
Level 3 (5)
81 dBA
75 dBA
68 dBA
Diesel
Driven
125-249 CFM
83 dBA
76 dBA
70 dBA
Diesel
Driven
250-599 CFM
86 dBA
73 dBA
73 dBA
Diesel
Driven
600-899 CFM
88 dBA
78 dBA
70 dBA
Diesel
Driven
Above 900 CFM
88 dBA
81 dBA
70 dBA
Notes: * (1) Levels constitute a "not to exceed" criteria
(2) Maximum sound pressure level in dBA at 7 meters according
to the recommended measurement practice of ISO 2151-1972.
A-10
-------
(3) Level 1 is associated with the average quieted air compres-
sors on the market today,, It would correspond to using ade-
quate enclosures, sound insulation and mufflers.
(4) Level 2 is associated with the best quieted machine on the
market. It would correspond to extensive enclosures, sound
insulation, sealing, cooling air silencing ducts and vibration
isolators.
(5) Level 3 is associated with the best demonstrated technology.
It would correspond to Level 2 plus more insulation, sealing
and possibly double walled enclosures.
Table A-6
ESTIMATED AVERAGE COSTS
(provided by Inge r soil-Rand)
I .e vel
Limit
Gasoline
Driven
75-249 CFM
Level 1 (2)
Level 2 (3)
Level 3 (4)
$2.59
$5.20
$26.00
Diesel
Driven
125-249 CFM
$2.59
$5.20
$26.00
Diesel
Driven
250-599 CFM
$3.14
$10.76
$10.76
Diesel
Driven
600-899 CFM
$1.80
$9.00
$13. 50
Diesel
Driven
Above 900 CFM
$1.60
$8.36
$12. 25
Notes: (1) Costs are estimated in additional dollars per CFM at manu-
facturers retail list price level.
(2) The costs cited in Level 1 represent the average increased
costs over standard unit to meet the dBA levels as specified
in Table I.
(3) The costs cited in Level 2 represent the average increased
costs over standard unit to meet the dBA levels as specified
in Table I.
(4) The costs cited in Level 3 represent the average increased
costs over standard unit to meet the dBA levels as specified
in Table I.
Ingersoll-Rand submitted no data to substantiate their altered figures. The
Company's additional comments on the draft A. T. Kearney and BBN reports are
addressed under II. General Issues.
Estimates of Time Required to Place State of the Air Technology into
Production (ANPRM #6)
Gimer stated that in the general experience of portable air compressor
A-ll
-------
industry members, a minimum of three years for market introduction of equip-
ment involving redesign is required; a minimum of five years for market intro-
duction of technology involving entirely new design. He qualified this statement
by:
• Variation among firms would occur depending on firms' financial and
technical position and the technology currently available to that firm
• The noise emission standard that must be met has yet to be specified.
Gimer warned that any suggestion that the industry is capable of meeting
requirements significantly below the current best available technology within
shorter time intervals (18 months was cited) would be regarded by the industry
as inaccurate and misleading and must be clearly substantiated.
Problems Resulting from Existing Noise Reduction Techniques
(ANPRM #11)
Both P.K. Lindsay and Gimer contended that quieting the compressor as a
unit was limited to a great extent by the noise emissions of the engine powering
the compressor. P. K. Lindsay enclosed catalog sheets citing specifications
for their various compressor models which incidentally made no reference to the
models' noise characteristics. All of the compressors manufactured by P.K.
Lindsay are powered by Teledyne Wisconson Engines with the exception of the
smallest, which is powered by a 9. 2 hp Briggs and Stratton Engine, and the
largest, which is powered by an 81 hp Ford Diesel Engine. P. K. Lindsay
pointed out that the operating noise levels of these engines alone approach
85 dBA at seven meters.
Docket inputs dealing with the availability of quieter engines from major
manufacturers of industrial engines, the relationship between compressor
silencing and engine noise emissions, and EPS's regulation of engine-powered
equipment prior to regulation of the engine itself are discussed under General
Issues in this Appendix.
A-12
-------
Effects of Portable Air Compressor Noise Reduction
(ANPRM #10 and #19)
Gimer commented that noise reduction of portable air compressors would
affect the following performance factors:
Size and Weight of Units. Generally, the manufacturer seeks to maintain
the performance parameters for each compressor when the standard unit in each
size catagory is silenced. As a consequence, the resulting machine is invariably
larger and heavier than the standard model with the same capabilities. The
silenced compressor is more difficult to tow than its standard counterpart. Due
to the physical size increase, in some instances the unit requires a larger
vehicle for towing than would be true of the standard unit of the same output
capability. Because it is not uncommon to transport compressors several units
at a time, increased size has also frequently meant that additional trucks or
flat beds are required to transport the same number of units.
Operating Conditions. It is estimated that anywhere from 5 to 15 degrees
Fahrenheit lower maximum ambient temperature must be available for sale
operation of a silenced unit.
Maintenance Costs. Maintenance costs on silent units will be higher due to
the lack of quick accessibility to some components, and the cost to replace seals.
Fuel Consumption. Data collected recently by CAGI on a confidential basis
i
indicates that for gas-powered units an average increase of 5% and up to 9% in
fuel consumption in shifting from a standard to a silenced model. For diesel-
powered equipment, the average increase is 3% with a maximum of 5%.
Gimer pointed out that while data collected by the Institute was not compre-
hensive enough to accurately project on a nation-wide basis the total impact of
silencing on fuel consumption, their studies clearly indicate that transition
from current standard models to silenced machines will have a definite fuel con-
sumption penalty. Gimer commented that any EPA regulation requiring silencing
beyond the noise emission levels associated with the silenced counterparts
A-13
-------
(ranging from 82 to 104 dBA at one meter) of current standard models, would
have an even more serious impact on total fuel consumption.
Component Storage. A shortage in both steel and platic components,
required in greater quantities in silenced units, can also be expected.
Current Regulations and Their Effects
Information on Existing and Planned Noise Regulations
(ANPRM #18)
The City of New York submitted a copy of its Noise Control Code (effective
September 1, 1972) Section 1403.3-5.11 of which regulates both the sale and
operation of air compressors. Air compressor is defined as a "device which
draws in air or gas, compresses its, and delivers it at a high pressure. " The
specific provisions of Section 1403.3-5.11 are as follows:
The Administrator of the New York City Environmental Protection Agency is
to promulgate regulations for measurement procedures which must be substan-
tially in compliance with similar ones promulgated by generally recognized pro-
fessional standard-setting organizations (including the Compressed Air and Gas
Institute).
The Code also provides discretionary authority to the Administrator for the
testing, inspection and registration of devices (Article II) and established hours
of operation for construction activities with variance provisions (Article HI,
Section 1403.3-4.11).
Gimer commented that in a very recent request for bids by New York City
for equipment to be delivered after June 1974, no compressor manufacturers
were able to respond as the step standard effective June 30, 1974 is 75 dBA at
one meter.
World Construction submitted the following chart citing various international
and municipal sound levels for compressors.
A-14
-------
Table A-7
INTERNATIONAL AND MUNICIPAL
PERMISSIBLE SOUND LEVELS FOR COMPRESSORS
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NEW YORK
§
The State of New York is developing a construction noise regulation which
is anticipated to be a performance standard setting decibel limits at a fixed
distance from a construction site based on the nature of the neighboring property.
Since noise limits will be established without regard to the exact type of con-
struction device generating the sound (and, therefore, will not be preempted by
EPA product regulations under Section 6 of the Noise Control Act), the State of
New York views this as an appropriate technique for control of construction
noise at the State level.
Impact on Industry of Existing Regulations (ANPRM #7)
World Construction submitted two editorials stating that conflicting National
and International noise standards with varying compliance schedules have
created confusion for both portable air compressor manufacturers and users,
and arguing that inconsistent environmental requirements replaces tariff barriers
with technical barriers.
A-15
-------
Gimer commence! that existing international regulations on compressor
noise emissions have not had a significant impact on the domestic compressor
industry, since, with limited exceptions, portable air compressors manufactured
in the U.S. are not sold for export. Gimer stated that the industry is concerned
with the proliferation of local government regulatory schemes that establish
stringent noise emission standards for compressors which cannot be met or
which unreasonably increase the costs of new machines (e.g., New York City).
Gimer contended that such regulations encourage prolonged use of existing units
which will result in a population of compressors with a higher overall noise
contribution than could be expected if reasonable uniform standards were adopted.
This point was also made by Ingersoll-Rand.
Compliance Methodology
Product Test Methodology for Compliance and Size of Product Sample
(ANPRM #20 and #21)
Gimer stated that CAGI strongly recommends that the methodology specified
for noise measurement in any Federal mandatory standard for portable air
compressors be that contained in ISO 2151. Gimer's arguments for the retention
of this measurement methodology byEPA are addressed under General Issues in
this appendix.
Gimer advocated that the full range of tests specified in any test code that
EPA adopts should not be performed on each and every unit manufactured, but
rather an appropriate sampling plan that could vary with the type of unit, the
quantity manufactured and the tolerances permitted by the standard.
IF EPA adopts the ISO 2151 basic test methodology, Gimer commented
that the costs of imploying this test would vary with the firm as the industry is
dispersed throughout the U.S., and therefore, seasons when outdoor testing can
be performed would differ. If compliance testing is required at frequenct
intervals, then some firms would have to construct covered facilities or hire
their own testing staff and purchase equipment to replace their present outside
consultant.
A-16
-------
Feasibility of Categorizing Product Models or Configurations According to
Their Noise Emission Characteristics (ANPRM #22)
Gimer recommended that the current means of classification of compressors
by power source and CFM output should be retained. Gimer commented that as
noise emission levels and, therefore, cost of compliance vary with each unit and
power source type, a regulatory scheme involving several different noise levels
might be warranted although confusing. Gimer stated that the industry's position
would be dependent on the noise emission standard EPA adopts.
Feasibility of Establishing a Useful Life (ANPRM #23)
The City of New York states that air compressors have an average life of
ten years. Gimer estimated that it was approximately eight years, though some
compressors have been in use for as much as 20 to 30 years. Gimer stressed
the need for proper and regular maintenance to preserve compressor noise
emission performance and pointed out that the quality of field maintenance varies
widely with the end-users, compressor applications, and operating environment.
Gimer commented that many end-users are not overly concerned with the main-
tenance of sheet metal and enclosure materials nor closing compressor doors.
High quality maintenance will be increasingly important with silenced compressors
as tight enclosure integrity is essential. Gimer cautioned that the responsibility
for normal care and maintenance of EPA regulated products should not be shifted
from the user to the manufacturer nor should the manufacturer be penalized
initially, in the adoption of noise emission standards, for poor maintenance
practices in the field.
GENERAL ISSUES RAISED IN THE DOCKET
Selection of Portable Air Compressors for Regulation
Three docket inputs, (Gimer, P. K. Lindsay and World Construction) ques-
tioned the validity of EPA regulating portable air compressors at this time.
Objections were raised that (1) portable air compressors had not been identified
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as a major source of noise in accordance with Section 5(b) of the Noise Control
Act and (2) EPA was apparently singling out portable air compressors for
regulation prior to alternative product candidates having noise contributions
that might be significantly higher.
Identification of Portable Air Compressors as a Major Source of Noise
Gimer contended that the regulatory approach apparently being utilized by
EPA (as of March 29, 1974), that of publishing simultaneously the Section 5(b)
initial identification document and Section 6 proposed regulations for the
identified products, while permissable under the Act was ill-advised for the
following reasons:
• Such a procedure leaves affected industries and the public in the dark
as to what criteria are being used by EPA to develop proposed
standards and all but deprives target industries of any opportunity to
show that a particular product or group of products should not be
subjected to mandatory emission limits; and
• Such as approach "appears to circumvent the intent of Congress that
EPA be required to develop a list of priorities, and to subject that
list to public scrutiny" with the advantages of focusing on Agency
priorities and helping to avoid arbitrariness in regulatory action.
With respect to portable air compressors, Gimer charged that:
• A vested interest in the regulation of compressors, through the expendi-
ture of funds and manhours prior to formal identification under Section
5(b), has been created.
• There is every evidence that EPA has in fact made a determination
that portable air compressors are "major noise sources" on an art hoc
basis.
• It appears that EPA contractors "have neither been requirited nor have
they accepted the responsibilities for defining the relationship between
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proposed emission limits and genuine safety considerations on the part
of workers or the general public".
Gimer's critique of EPA's regulatory approach is based on his interpretation
of EPA's activities at the time of his docket submittal (March 29, 1974). On
June 19, 1974, the identification of medium and heavy duty trucks and portable
air compressors as major sources of noise in accordance with Section 5(b) of
the Noise Control Act was published in the Federal Register. This initial
identification document delineated the approach used by EPA to identify major
sources of noise and fulfills Gimer's recommendation that EPA's regulatory
priorities and their derivation be available for public scrutiny before publication
of proposed noise emission standards under Section 6.
The EPA has continually stressed the importance of affording interested
parties an opportunity to participate in all stages of the rule-making process.
Gimer's statement that the approach apparently being adopted by EPA "all but
deprives target industries of any opportunity to show that a particular product
or group of products should not be subjected to mandatory emission limits" is
belied by his own response to the ANPRM. The issues and information con-
tained in this docket were considered by EPA prior to publication of the formal
identification of portable air compressors as a major source of noise.
The following considerations should be taken into account in assessing >
Gimer's three criticisms of EPA's approach to regulating portable air com-
pressors:
1. Tn fulfilling its responsibility to identify those products or classes of
products which are major sources of noise, EPA contracted for the
preparation of economic and technology studies on a variety of product
sources. As in the case of portable air compressors, the background
data compiled may be utilized in future regulatory activities. Neither
the existence of such product data nor the resource expenditures incurred
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in obtaining this information create a vested regulatory interest; rather
they reflect EPA's efforts to initiate its regulatory activities from as
broad a data base as possible.
2. Both the identification report and Section 2 of this document explain
the basis for EPA's determination that portable air compressors are a
major source of noise. In the absence of a universally accepted method
to determine which noise sources pose the most serious threat to
public health and welfare, EPA has made an effort to take into account
the many factors affecting public health and welfare in the identification
process. As was stated in the initial identification report, "ultimately,
however, the identification of major noise sources must be partly sub-
jective". It does not follow from this as Gimer suggests that "EPA
has in fact made a determination that portable air compressors are
'major noise sources' on an ad hoc basis. . . ".
3. It has never been the intention to shift EPA's responsibility to define
the health and welfare basis of regulatory activities to contractors
whose function is rather to compile and analyze economic and technological
data and submit expert reports to EPA for consideration. The two
documents "Public Health and Welfare Criteria" and "Information on
Levels of Environmental Noise Requisite to Protect Public Health and
Welfare with an Adequate Margin of Safety " comprise the definitive
information used in emission standards. An evaluation of the public
health and welfare basis for the regulation of portable air compressors
is contained in Section 10 of this document.
Advocated Candidates for Prior Regulation
Three docket inputs, those of World Construction, P. K. Lindsay and Gimer
questioned the regulation of portable air compressors before the establishment
of noise emission standards for other products or components.
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One of the editorials submitted by World Construction cited industry objections
to compressors being singled out for regulation by countries and municipalities
when "the compressor-powered tool may be the greatest offender".
P. K. Lindsay has assumed that EPA would establish maximum noise limits
for construction equipment as a class rather than regulate specific items of
equipment. P. K. Lindsay maintained that compressor noise reduction is
dependent on the availability of quieter engines, and under EPA's separate
item approach, an engine used on a compressor which would not meet EPA noise
emission standards could continue to be sold for use on other unregulated
construction equipment.
Gimer advocated thatnoise emission standards be established for internal
combustion engines arguing as follows:
• With many products utilizing internal combustion engines, the noise
contribution of the engine itself exceeds that of the other components
of the equipment involved as is frequently the case with portable air
compressors. The noise emissions from the engine set a practical
limit to the amount of quieting which can be obtained on a compressor
by various insulating means or redesign approaches.
• Compressor manufacturers generally purchase internal combustion
engines from engine manufacturers rather than fabricate the engines
themselves. Representing but a small segment of the total consumption
of engines, compressor manufacturers are powerless to dictate the
noise emission levels of engines. Any attempt to do so would force
engine manufacturers to divert their production to other end uses.
Other industries, whose products emit noise largely traceable to internal
combustion engines and who may be the target of future EPA noise
emission standards, also have little market control over engine noise
emissions.
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• Section 6(a)(l)(c)(iii) of the Noise Control Act clearly contemplates that
engines, not just engine powered machines and equipment are to be
priority targets of EPA regulatory attention. The noise contribution
of internal combustion engines may be the major source of noise for
each of the other categories specified in Section 6(a)(l). However,
EPA has shifted the focus of attention from the engine to the engine
powered device itself - a determination in conflict with the Noise
Control Act unless the Administrator finds the regulation of engines
themselves is not feasible.
Given the constraints of scarce resources and the desire to assess in depth
the health and welfare, cost and technology factors that have a bearing on the
feasibility of noise emission controls, EPA has initiated its implementation of
Section 6 of the Noise Control Act with the proposed regulation of two products
which have been identified as major sources of noise. Other products or classes
of products identified as major noise sources and falling into one of the four
categories specified in Section 6(a)(c) will be regulated in the future if in the
Administrators' judgment noise emission standards are feasible for such pro-
ducts. There is no validity to Gimer's assertion that EPA has chosen to ignore
the contribution of engines or motors as sources of noise or that the statutory
category "Motor or Engine" has been transformed to "Internal Combustion Engine
Devices". It does not follow that as internal combustion engines are not one of
the two products for which noise emission standards will be prescribed initially,
they are therefore precluded from future regulation. EPA has in the past and
continues to collect and analyze cost and technology data on a variety of new
products as part of the identification process of major noise sources.
As is delineated in Section 2 of this document, EPA gave first priority to
sources that contribute to community noise exposure in its identification of
portable air compressors as a major source of noise. Although, as P. K. Lindsay
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and Gimer state, engines are predominant contributors to air compressor noise,
quieting technology is available as is shown in Section 8 and has been used by
various manufacturers to significantly reduce the noise emission levels of their
products. For EPA to have promulgated regulations incorporating noise emission
standards for construction equipment as a class, as P. K. Lindsay advocates,
might have placed an unacceptable economic burden on the construction industry.
EPA's Eegulatory Approach
Several Docket inputs advocated specific regulatory orientations and suggested
provisions to be incorporated into a regulation for portable air compressors
which are presented below.
EPA Should Place Primary Emphasis on Safety Factors
Gimer stated that EPA regulations incorporating noise emission standards
must have a safety related basis and cited the statutory language of Sections
5(a)(2), 6(b) and 6(c)(l) of the Noise Control Act as evidence of the Congressional
intent that noise emission standards be based upon genuine safety considerations.
Gimer charged that "notwithstanding these explicit directives in the Act, the
approach apparently being adopted (at least by the firm hired by EPA to recom-
mend a noise emission limit) is that the standard to which portable compressors
should perform is dictated by the level of noise emission attainable by the
'application of the best available technology'." Gimer contended that such an
approach would violate the clear mandate of the Noise Control Act and would be
unfair to the industry by shifting the burden of proof of a regulation's safety
basis from EPA to the industry. Gimer argued that EPA should consider not
only available technology, but the presence or absence of a safety consideration
as well as both industry and consumer economic impact prior to publication of
a proposed regulation.
EPA is well aware that its statutory authority to establish noise emission
standards for porducts distributed in commerce is founded on the Congressional
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statement of policy contained in Section 2(b) of the Noise Control Act - that of
promoting "an environment for all Americans free from noise that jeopardizes
their health and welfare11. In his legal interpretation of the mandates of the Noise
i«
Control Act, Gimer seems to have shifted the statutory emphasis on public health
and welfare, counting as it does populations in the aggregate, to safety consider-
ations. Contrary to Gimer's assertion, the Noise Control Act is very explicit
in the factors which must be addressed by EPA prior to proposing or promulgating
regulations under Section 6. As stated in Section 6(c)(l) any regulation must
include a noise emission standard "which in the Administrator's judgment, based
on criteria published under Section 5, is requisite to protect the public health
and welfare, taking into account the magnitude and conditions of use of such
products (alone or in combination with other noise sources), the degree of noise
reduction achievable through the application of the best available technology, and
the cost of compliance". There is no validity to Gimer's contention that the best
available technology will be the sole determinant of the noise emission standards
for portable air compressors which EPA will propose. As reflected in this
project report, EPA has carefully weighed public health and welfare implication,
product use, cost of compliance, best available technology and various other
factors in its regulatory process.
Regulation Data Base
Gimer and Ingersoll-Rand questioned the availability and validity of informa-
tion contained in EPA contractor reports.
Gimer pointed out that while the Compressed Air and Gas Institute could not
collect and synthesize data in response to every question raised in the ANPRM
for anti-trust reasons, the Institute had encouraged its members to supply EPA
and its contractors with sensitive cost and pricing data. He stated that this
procedure leaves both industry and the government in a difficult position in dealing
with the conclusions reached when the raw data fed into the decision making pro-
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cess is not available. The Institute is deferring any judgment on the accuracy or
appropriateness of data compiled or contractor recommendations until the final
reports are available for public review.
Ingersoll-Rand contested various aspects of both the draft Bolt, Beranek
& Newman Report and the A. T. Kearney Report. Ingersoll-Rand maintained that
the Level Three noise level indicated in the draft BBN Report are completely
unrealistic as they could be extremely difficult to achieve, very expensive and
virtually impossible to check in the market place due to the tremendous
influence of ambient noises. Ingersoll-Rand submitted tables in lieu of those
contained in the BBM Report which are presented under the information section
of this analysis. Ingersoll-Rand also contested specific statements contained
in the draft A. T. Kearney Report and questioned its conclusions which were
based on levels of noise emission and standards of cost with which Ingersoll-
Rand basically disagreed.
EPA appreciates the cooperation of the Institute, its members and other
compressor manufacturers in supplying product information to EPA and its
contractors. In accordance with EPA's policy of affording interested parties
an opportunity to participate in rule-making, the data available to EPA including
the final contractor reports will be open for public inspection and comments
on these reports will be welcomed.
Ingersoll-Rands' comments on the draft contractor reports have been
considered by EPA. However, as these reports were preliminary findings and
as little data was provided by Ingersoll-Rand to substantiate their figures, it is
felt to be more appropriate to address the points Ingersoll-Rand may choose to
raise on the final report used in the rule-making process.
Measurement Methodology
Gimer strongly advocated that the measurement methodology specified in
any EPA regulation for portable air compressors be that contained in the CAGI-
A-25
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PNEUROP test code which has been codified as a national consensus standard and
an international standard in ANSI S5.1-1971 and ISO 2151 respectively. Gimer
pointed out that the code reflects the considered judgment of the world's leading
acousticians and interested government officials in addition to that of U.S. and
European compressor manufacturers. Gimer argued that if EPA were to ignore
existing internationally recognized standards, the result would be to discourage
the massive voluntary effort that has been made to develop these standards and to
dry up this source of standard-making activity. In addition, Gimer contended
that changes to this methodology with which the domestic industry is accustomed,
would add to the cost of testing as many manufacturers would be forced to test
with both the EPA and ISO 2151 methodologies.
Gimer stated that a proposal for measuring compressor noise emission
has been drafted and was being circulated for comment to the appropriate ISO
committees and members. This proposal would require measurement of upward
radiated noise in addition to the side measurements currently required by ISO
2151 and would add guidelines for determining sound power as contrasted with
the sound pressure measurements currently required. Gimer cautioned that the
precise impact on the dBA rating of any given compressor of factoring in a
measurement of upward radiatedi noise cannot be known at this time although tests
indicate that the dBA rating for most compressors currently available will differ
with the addition of a top level measurement. Gimer also pointed out that
virtually all data previously collected do not reflect the effects of upward
radiated noise emissions. Gimer urged that if EPA thought revisions to ISO
2151 were needed, the appropriate action would be for EPA to participate in the
ongoing revision of that standard.
The measurement methodology EPA is proposing is delineated in Section 6
of this project report. Following data collection using alternative measurement
procedures, EPA determined that the measurement methodology specified in
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Section 6, which combines the essential features of the CAGI-PNEUROP Test
Code with a measurement for upward radiated noise, provides an adequate
description of portable air compressor noise. EPA has and will continue to
cooperate and participate in the standards setting activities of both national and
international professional organizations. The fact that an ISO proposal has
been drafted would seem to signify that in at least some segments of the
acoustical community a revision of the CAGI-PNEUROP Test Code is considered
desirable. Finally, Gimers' contention that EPA's adoption of a measurement
methodology other than the CAGI-PNEUROP Test Code would increase testing
costs is not in accordance with his statements that, with very limited exceptions,
portable air compressors manufactured in the U. S. are not sold for export. In
most instances, domestic manufacturers would only be required to test using the
EPA procedures.
Sufficient Lead Time for Manufacturer Compliance
P. K. Lindsay urged EPA to establish reasonable noise emission levels and
to give compressor manufacturers, and the engine manufacturers upon which all
compressor manufacturers are dependant, sufficient time to develop, test,
and get into production the quieter units desired.
As is stated in Section 7, the proposed compliance schedule is one year
from the date of promulgation of the final regulation. In EPA's judgment, this
schedule will enable compressor manufacturers to utilize quieting technology
without unacceptable economic consequenses.
Provision for Compressor Use and Compressor Size
World Construction submitted an editorial arguing for consistency in regula-
tions and citing deficiencies in approach and content of existing air compressor
noise suppression standards and regulations. Two such criticisms were that no
allowance is made for (1) the size of the compressor or (with the exception of
West Germany) or (2) the nature of the job site (with the exception of Japan).
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Gimer suggested EPA consider whether it is justifiable to impose a single
uniform standard on all portable air compressors (or any other product subjected
to regulation) for all its uses throughout the entire country. Pointing out that
there are different social implications from the noise emitted by a compressor in
downtown New York City to that used in an isolated rock quarry, Gimer questioned
whether the incremental cost of complying with an EPA regulation should be borne
by the product consumer in uses when the requirements were unnecessary. Gimer
suggested EPA consider a type of classification scheme being developed in
Europe in which two or more classes of silenced units would be required in more
populated areas and one or more classes of other units could be used nationally
except where municipal governments adopted regulations limiting compressors
used in specific areas to the silenced classes. Gimer questioned the statutory
language of Section 6 stating that while "the Act does not clearly require a
single standard for all products within a category, regardless of intended use",
the "statute is clearly product oriented",, Gimer stated that the Institute intended
to submit further comment on this subject following publication of the NPRM.
Gimer also commented that not enough emphasis had been placed by users and
government officials upon reducing compressor noise emissions although the
use of barriers and selection of compressor location on the job site as; is permitted
in existing European regulations.
As explained in Section 7 of this project report, EPA's proposed regulation
does not make allowance for the size of the compressor, since it has been
demonstrated that the noise generation of currently available quieted compressor
models is not significantly dependent on the size of the unit.
Section 6 of the Noise Control Act is explicit in defining the division of
authority between the Federal government and states or political subdivisions.
While, as is stated in Section 2(a)(s) of the Act, "Federal action is essential to
deal with major noise sources in commerce control of which requires national
A-28
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uniformity of treatment", States and localities retain jurisdiction to establish
and enforce controls on environmental noise "through the licensing, regulation,
or restriction of the use, operation, or movement of any product or combination
of products". EPA does not have the authority to propose or promulgate any
regulation under Section 6 that would establish differing noise emission require-
ments on the basis of a products intended use. Similarly, EPA does not have
the authority to incorporate provisions for barriers or compressor site location
in a noise source regulation.
Inclusion of Retrofit Provision
The City of New York advocated that due to the large number of compressors
in use with an average life of ten years, EPA should consider a retrofit program
and recommended the following noise emission standards for inclusion in a retro-
fit regulation:
"Air compressors rated at 600 CFM or greater should be reduced to a level
of 95 dBA at one meter while air compressors below 600 CFM could be reduced
to 90 dBA at one meter. "
The Noise Control Act does not authorizeEPA to regulate in-use products,
and therefore EPA has no authority to propose a retrofit regulation for compressors.
Suggested Noise Emission Standards
Three docket inputs recommended specific noise emission standard for EPA's
consideration.
1. The City of New York, based on its experience, stated that the following
standards in their views would not impose an economic burden on either
the manufacturer or operator of the equipment:
"All air compressors manufactured one year after passage of this
regulation, and having a rated capacity of 600 CFM or more shall not
exceed 85 dBA at one meter. Further, all air compressors having a
rated capacity below 600 CFM shall not exceed 75 dBA at one meter".
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2. Ingersoll-Rand recommended a maximum silencing of 70 dBA at 7
meters arguing as follows:
a. This level is feasible and portable air compressors would still
be the quietest machine on the construction site;
b. Other contributing noise sources at a construction site produce
levels well over 85 dBA at 7 meters that can only be reduced by
5 to 10 dBA at 7 meters in the future; and
c. To set a lower level would (i) increase costs of all construction
work, (ii) not benefit the environment because of all ambient
noises, and (iii) stimulate an extended useful life of existing
equipment thereby worsening rather than improving the noise
levels associated with compressors.
3. P. K. Lindsay advocated that an overall limitation of 85 dBA at 7 meters
is reasonable based on the following considerations:
a. The operating noise levels of engines currently used to power
P. K. Lindsay's compressors approach 85 dBA at 7 meters,
b. OSHA's standard governing occupational noise exposure sets a
maximum permits able level of 90 dBA for eight hours. A work-
man using a compressor would be 7 or more meters away except
for the few minutes required to start or shut down the unit; and
c. If EPA were to set a standard lower than 85 dBA at 7 meters,
P. K. Lindsay would have little alternative other than to close down.
EPA has considered these recommended noise emission standards together
with the arguments advanced for their selection in the rule-making process. The
background data and findings utilized by EPA in formulating the proposed regulation
for portable air compressors are presented in this project report.
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Appendix B
METHOD TO EVALUATE THE IMPACT OF PORTABLE AIR COMPRESSOR
NOISE ON PUBLIC HEALTH AND WELFARE
-------
LIST OF TABLES
TABLE TITLE PAGE
B-l Sound Level Reduction Due to Houses in B-8
Warm and Cold Climates, with Windows Open
and Closed
B-2 Estimate of the Impact of Successive B-12
Reduction of all Urban Noise Sources in
5 Decibel Increments
-------
Appendix B
METHOD TO EVALUATE THE IMPACT OF PORTABLE AIR COMPRESSOR
NOISE ON PUBLIC HEALTH AND WELFARE
SPECIFICATION OF NOISE ENVIRONMENT
Environmental noise is defined in the Noise Control Act of 1972 as the
"intensity, duration, and the character of sounds from all sources". A
measure for quantifying environmental noise must evaluate not only these
factors, but must also correlate well with the various modes of response of
humans to noise and be simple to measure (or estimate).
EPA has chosen the equivalent A-weighted sound pressure level in decibels
as its basic measure for environmental noise. The general symbol equivalent
level is L , and its basic definition is:
eq
where t - t is the interval of time over which the levels are evaulated, p(t) is
£ 1
the time varying sound pressure of the noise, and p is a reference pressure,
standardized at 20 micropascal.
When expressed in terms of A-weighted sound level, L , L may be defined
a eq
as:
10 —dt
B-l
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The primary interval of interest for residential and similar land uses is a
twenty-four hour period, with weighting applied to nighttime noise levels to
account for the increased sensitivity of people associated with the decrease in
background noise levels at night. This twenty-four hour weighted equivalent
level is called the Day-Night Equivalent Level, and is symbolized as L . The
an
basic definition of L, in terms of A-weighted sound level is:
dn
Ldn=101°gloi4-
Ldn=101°g10 24
2200
0700
10
10
0700 /
dt -f 9 / 10
J2200
or
(15 x 1010) + (9 x 10
L + 10
n
10
(t) - 10
10
(B-3)
(B-4)
where L, is the "daytime" equivalent level, obtained between seven a. m. and
d
ten p.m. and L is the "nighttime" equivalent level obtained between ten p.m.
and seven a. m. of the following day.
ASSESSING IMPACT FROM ENVIRONMENTAL NOISE
The underlying concept for noise impact assessment in the following
analysis is to relate the change in expected impact in terms of the number of
people involved to the change that will result in the acoustical environment as a
result of the proposed action. Three fundamental components are involved in the
analysis:
1. Definition of the initial acoustical environment
2. Definition of final acoustical environment
3. Relationship between noise environment and human impact.
B-2
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The first two components of the assessment are entirely site or system
specific, relating to either estimates or measurement of the environmental
noise before and after an action is taken. The same approach is used concep-
tually whether one is examining one house near a highway, a house near a con-
struction site, the transportation system in general, or whatever noise source
is involved. The methodology for estimating the noise environment in each
case will vary widely, but the concept remains the same.
In contrast to the large number of methodologies that may be utilized to
estimate the noise environment, the relationship to human response can be
quantified by a single methodology in terms of the number of people in occupied
places exposed to noise of a specified magnitude. This is not to say that
individuals have the same susceptibility to noise; they do not. Even groups of
people may vary in response depending upon previous exposure, age, socio-
economic status, political cohesiveness and other social variables. In the
aggregate, however, for residential location the average response of groups of
people is stable and related to cumulative noise exposure as expressed in
measures such as L, or L . The response utilized is the general adverse
dn eq
reaction of people to noise. This response is a combination of such factors
as speech interference, sleep interference, desire for a tranquil environment,
and the ability to use telephones, radio and TV satisfactorily. The measure
itself consists in relating the percent of people in a population that would be
expected to indicate a high annoyance to noise for a specified level of noise
exposure.
For schools, offices, and similar spaces where criteria for speech com-
munication or a possibility of damage to hearing is of primary concern, a
similar averaging process is used to estimate the potential response of people
as a group, again ignoring the individual variation of one person as compared
to another.
B-3
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In both instances, then, residential or similar areas and non-residential
areas alike, the analysis is performed in terms of the average response of
people and its variation with environmental noise exposure.
A detailed discussion of the relationship between noise and human response
n 28i
is provided in several EPA documents ' in which hearing damage, speech
and other activity interference and annoyance are related to L and L . For
the purpose of the following analysis, criteria presented in the "EPA Levels
Document" are used. Further, it is considered that if the levels identified in
the document are met, then no impact exists on the public health and welfare.
Thus, arbitrarily we define that if the levels identified in the "Levels Document"
are met, a zero percent impact exists. That is,if an L, of 55 measured out-
cm
door exists, then there is no impact in terms of annoyance and general community
response from noise. Similarily, if an L of 45 exists indoors, which trans-
lates to an L, of 55 outdoors assuming a 10 dB transmission loss with window
partially opened, then no interference exists with respect to speech.
Observation of the data presented in Appendix D of Reference 1 allows the
specification of an upper limit, that is a bound corresponding to 100% impact.
It may be observed in Figure D-7 of the "Levels Document" that community
reaction data show that the expected reaction to an identifiable source of intruding
noise changes from "none" to "vigorous" when the day-night sound level increases
from 5 dB below the level existing without the presence of the intruding noise to
19. 5 dB above the pre-intrusion level. When the combined values of the intruding
noise and the pre-intrusion noise levels are considered, the changing community
reaction from "none" to "vigorous" occurs when the level increases by 19.7 above
the pre-intrusion level. For simplicity sake, it is reasonable to associate 100%
impact corresponding to a vigorous community reaction with a change of 20 dB
above the L, value identified as a zero impact level. This conclusion is further
cm
validated by the annoyance data presented in the "Levels Document", since this
B-4
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increase in noise level increases the rate of highly annoyed people in the total
exposed population by 40%.
Thus, for the purpose of this analysis, L = 75 is considered to be a 100%
impact,
Furthermore, the data in Appendix D of Reference 1 suggest that within
those upper and lower bounds the relationship between impact and level varies
linearly, that is, a 5 dB excess constitutes a 25% impact, while a 10 dB excess
constitutes a 50% impact.
The data presented in the "Levels Document" with respect to activity inter-
ference (e. g., speech interference) suggests that if the day-night sound level
indoors is 45 dB, no impact exists on speech communication since a noise
level intelligibility for all types of speech material and would have a calculated
articulation index of 1.0.
The intelligibility of speech is a function of the material presented to the
listener as well as the signal to noise ratio. Data on speech intelligibility
has recently been reviewed in several of the EPA documents and also by an ANSI
committee for the preparation of the ANSI S3. 5-1969, and is summarized in
Figure 15 of Reference 29.
It may be argued that for most conversation the material the listener nor-
mally listens to is in the form of sentences containing a mixture of some known
material and some unknown material. Thus, for this analysis it is reasonable
to average the data on known and unknown sentences. Observation of Figure 15
[29]
of the ANSI Standard reveals that when the noise environment is increased by
approximately 19 dB above the level identified in the "Levels Document."
Similarily, the intelligibility for known sentences drops to 90% when the level is
increased by 22 dB above the level identified by EPA and 50% when the level is
increased by approximately 26 dB. Thus, if the values are averaged, it is not
unreasonable to assume that a 20 dB increase in the noise level above the level
identified by EPA in the "Levels Document" will result in conversational speech
B-5
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deteriorating rapidly with each decibel of increase. For this reason, it is
assumed that 100% impact will occur on speech intelligibility when the level of
the environmental noise increases 20 dB above the identified level in the "Levels
F291
Document". Furthermore, observation of Figure 15 of the ANSI Standard
suggests that it is reasonable to assume that speech varies approximately
linearly with the level for the range between 0 and 100% impact. That is, with
each 5 dB excess of noise above the level identified in Reference 1, a 20%
reduction of speech intelligibility occurs while a 10 dB excess results in a 50%
degradation.
The previous paragraphs demonstrate that for impact analyses, it is rea-
sonable to consider that annoyance data, community reaction data, and speech
interference data, fall within a range of 20 dB corresponding to 0 and 100%
impact when 0% impact is defined as being the level identified in the "Levels
Document" and 100% impact as being the level which is 20 dB above the levels
identified in the "Levels Document".
For convenience of calculation, the percentage between 0 and 100 may be
expressed in terms of a Fractional Impact (FI), where FI is calculated in
accordance with the following formula:
FI = 0. 05 x (L - L ) for L >L
l^ L-'
FI = 0 for L < L
\_/
where L is the environmental noise level, expressed either in L , or L , and
dn eq
L is the level identified in the Levels Document.
c
It may be observed that for values greater than those corresponding to 100%
impact, the FI will be greater than unity. The effect of this will be to maximize
the impact weight for those areas in which the impact is only marginal. The
appropriate level for the computation of FI is L, = 55 dB for residential area
measured outdoors and for analysis concerned with office buildings and other
type of spaces in which speech communication is the principal factor of concern,
B-6
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the identified level is L, =45 indoors, which can be translated to an outdoor
dn
level by using sound level reduction appropriate to the type of structure.
Data on the reduction of aircraft noise afforded by a range of residential
structures are available. These data indicate that houses can be approximately
categorized into "warm climate" and "cold climate" types. Additionally, data
are available for typical open-window and closed-window conditions. These data
indicate that the sound level reduction provided by buildings within a given
community has a wide range due to differences in the use of materials, building
techniques, and individual building plans. Nevertheless, for planning purposes,
the typical reduction in sound level from outside to inside a house can be sum-
marized as follows in Table B-l. The approximate national average "window-
open" condition corresponds to an opening of 2 square feet and a room absorption
of 300 sabins (typical average of bedrooms and living rooms). This "window-
open" condition has been assumed thoughout this chapter in estimating conser-
vative values of the sound levels inside dwelling units that results from outdoor
noise.
The final notion to be considered is the manner in which the number of
people affected by environmental noise is introduced into the analysis. The
magnitude of the total impact associated with a defined level may be assessed by
multiplying the numbers of people exposed by the fractional impact associated
with the level of the environmental noise as follows:
Peq = (FI) ) (B-5)
where P is the magnitude of the total impact on the population and is numerically
eq
equal to the equivalent number of people having a fractional impact equal to unity
(100% impacted^; FI is the fractional impact for the level and P is the population
affected by the noise.
B-7
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Table B-l
SOUND LEVEL REDUCTION DUE TO HOUSES* IN WARM
AND COLD CLIMATES, WITH WINDOWS OPEN AND CLOSED
Warm Climate
Cold Climate
Approx. National Average
Windows
Open
12 dB
17 dB
15 dB
Windows
Closed
24 dB
27 dB
25 dB
*(Attenuation of outdoor noise by exterior shell of the house)
Where knowledge of structure indicates a difference in noise reduction from
these values, the criterion level may be altered accordingly.
B-8
-------
When assessing the total impact of a given noise source, or an assemblage
of noise sources, and since the levels of environmental noise associated with the
source(s) decrease as the distance between the source and receiver increases,
the magnitude of the total impact may be computed by determining the number of
people exposed at each level, and summing the resulting impact. The total
impact is given by the following formula:
P = T; P.FI. (B-6)
eq r" i i
where FI. is the fractional impact associated with the i level and P. is the
th
population associated with the i level.
The change in impact associated with an action leading to noise reduction,
or change in population through a change in land use, may be assessed by com-
paring the magnitude of the impacts for the "before" and "after" conditions.
Another useful measure is the percent expression:
(P (before) - P (after) )
100 —^~- — -^ (B-7)
P (before) l '
eq l ;
Note that the percentage change may be positive or negative depending upon
whether the impact decreases (positive percentage reduction) or the impact
increases (negative percentage reduction).
Thus, a 100 percent positive change in impact means that the environmental
noise has been reduced such that none of the population is exposed to noise
levels in excess of the levels identified in the "Levels Document."
To place this concept in perspective, we consider a simple example. In
the recent EPA study on "Population Distribution of the United States as a
B-9
-------
Function of Outdoor Noise Level," an estimate is provided for the number of
people in the United States exposed to various levels of urban noise. We can
use the above concepts to illustrate the current impact of this exposure, and
then to assess the change in impact if all noise sources were reduced 5, 10, or
15 dB across the board. In the following computation we take the data from
this study defining each P. as the population between successive 5 dB increments
of L , assigning this population an exposure level midway betwen successive
L, increments. For this example, the identified level is an L, of 55 dB
dn dn
measured outdoors.
The results, provided in Table B-2, show that a 5 dB noise reduction
results in a 55% reduction in impact, a 10 dB noise reduction results in an 85%
reduction in impact, and a 15 dB noise reduction results in a 96% reduction in
impact.
The impact assessment procedure may be summarized by the following
steps:
1. Estimate the L or L , produced by the noise source system as a
eq dn
function of space over the area of interest.
2. Define subareas of equal L or L, , in increments of 5 dB, for all
eq dn
land use areas.
3. Define the population, P., associated with each of the subareas of
step 2.
4. Calculate the FI. values for each L, or L obtained in step 2.
i dn. eqL
5. Calculate FI x P. for each subarea in step 2.
i i
6. Obtain the equivalent impacted population for the condition existing
before the change being evaluated,
p - y (FI. x P.)
eqB ^ i i'
by summing the individual contributions of step 5.
B-10
-------
7. Repeat steps 1-6 for the noise environment existing over the area of
interest after the change being evaluated takes place, thus obtaining
P . (Note that the subareas defined here will not in general be con-
gruent with those of step 2 above.)
8. Obtain the percent reduction in impact from
(P - P )
eq eq '
A . 100 B
P
e
B-ll
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