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Noise red flag tables

Get information on noise requirements for equipment that must be met when applying for an environmental approval.

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Developed in 1997 and reviewed for accessibility in January 2017.

Scope

This publication, "Noise red flag tables", provides reference distances to achieve a sound level of 50 dBA for equipment subject to approval by the Ministry of the Environment and Climate Change (MOECC).

Twelve distinct groups of typical industrial noise sources are represented in the tables in terms of their power rating or a combination of other operating parameters which correlate with the noise emissions.

General assumptions for all sources in red flag tables

Attenuation due to the ground is based on international standard ISO 9613-2, "Acoustics – Attenuation of sound during propagation outdoors, Part 2: General method of calculation".
Atmospheric attenuation is based on data for "Standard Day" in Table 6-1 of the BBN report, "Noise Control for Buildings and Manufacturing Plants", by Bolt Beranek and Newman Inc.
Noise sources are assumed not to be enclosed, and have not been treated with any type of sound absorbent material (with the exception of diesel generators). It is assumed that the generator is enclosed in a room composed of concrete block walls, concrete floor, and a drywall ceiling. It is further assumed that the area of the intake opening is 1.5 m².
Noise sources are assumed to be 3 m above ground level (with the exception of fans, which are assumed to be 5 m above).

References

Air compressors

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Asphalt burners

Environmental Noise In and Around Hot Mix Asphalt Plants, NAPA IS-63

Boilers

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Chillers

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Cooling towers

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

De-barking drum

Noise Control Solutions for Paper Products Industry, Richard K. Miller, Wayne V. Montone, & Mark d’Oviat

Diesel engines

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Fans

1987 ASHRAE HVAC Handbook, Chapter 52

Flares

Concord Environmental Noise Study, Straitz 1977, Swithenbank, 1972

Motors

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Pumps

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Steam turbines

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Steam valves

Noise Control for Buildings and Manufacturing Plants, Bolt Beranek and Newman Inc., 1981

Air compressors

(1–75 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1–2	70
3–9	90
10–75	120

Asphalt plant burners

Gas fired

Burner rating (MkJ/hr)^{footnote 1[1]}	Distance corresponding to 50 dBA (D₅₀) (m)
5	65
10	155
15	275
20	415
25	575
30	745
5	925
40	> 1,000
45	> 1,000
> 50	> 1,000

Oil fired

Burner rating (MkJ/hr)^{footnote 2[2]}	Distance corresponding to 50 dBA (D₅₀) (m)
5	55
10	130
15	225
20	340
25	465
30	600
35	745
40	900
45	> 1,000
50	> 1,000
55	> 1,000
60	> 1,000
> 65	> 1,000

Low noise (with hush kit)

Burner rating (MkJ/hr)^{footnote 3[3]}	Distance corresponding to 50 dBA (D₅₀) (m)
5	20
10	40
15	60
20	80
25	100
30	130
35	160
40	190
45	220
50	250
55	290
60	320
65	360
70	400
75	440
80	480
85	530
90	570
95	620
100	660

Boilers

(50–2,000 BHP)

Boiler Power (BHP)^{footnote 4[4]}	Distance corresponding to 50 dBA (D₅₀) (m)
50–300	65
301–2,000	87

Chillers

Input data: Cooling capacity (tons)

1 ton of cooling capacity is defined as the amount of heat removal required to produce 1 ton of ice per 24 hour period, or 12,000 BTU/hr.

Reciprocating compressors

Cooling capacity (tons)	Distance corresponding to 50 dBA (D₅₀) (m)
10–30	59
31–80	77
81–200	103

Rotary-screw compressors (100–300 tons)

At or near 3,600 RPM

Cooling capacity (tons)	Distance corresponding to 50 dBA (D₅₀) (m)
100–300	88

Centrifugal compressors (100–1,000 tons)

Internally geared & hermetically sealed

Cooling capacity (tons)	Distance corresponding to 50 dBA (D₅₀) (m)
100	85
150	100
200	110
250	120
300	125
350	135
400	140
450	145
500	150
550	155
600	160
650	165
700	170
750	175
800	180
850	185
900	190
950	190
1,000	195

Rotary centrifugal compressors (100–1,000 tons)

Direct driven & hermetically sealed

Cooling capacity (tons)	Distance corresponding to 50 dBA (D₅₀) (m)
100	50
150	60
200	70
250	80
300	85
350	95
400	100
450	110
500	115
550	120
600	130
650	135
700	140
750	145
800	150
850	155
900	160
950	165
1,000	170

Centrifugal compressors (> 1,000 tons)

Hermetically sealed

Cooling capacity (tons)	Distance corresponding to 50 dBA (D₅₀) (m)
1,000	245
1,250	255
1,500	270
1,750	275
2,000	285
2,250	295
2,500	300
2,750	310
3,000	315
3,250	320
3,500	325
3,750	330
4,000	335
4,250	340
4,500	345
4,750	350
5,000	355
5,250	355
5,500	360
5,750	365
6,000	370
6,250	370
6,500	375
6,750	380
7,000	380

Cooling tower

1–100 HP

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	42
5	68
10	86
15	98
20	108
25	116
30	124
35	130
40	136
45	142
50	148
55	155
60	160
65	165
70	165
75	170
80	175
85	180
90	180
95	185
100	190

100–1,000 HP

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	190
150	225
200	255
250	280
300	305
350	325
400	340
450	360
500	375
550	390
600	405
650	420
700	435
750	445
800	455
850	470
900	480
950	490
1,000	500

De-barking drum

Distance corresponding to 50 dBA (D₅₀) (m)
225

Diesel engine intake and casing

RPM > 1,500 (50–1,500 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
50	90
100	115
150	135
200	150
250	165
300	180
350	190
400	200
450	210
500	220
550	225
600	235
650	245
700	250
750	255
800	265
850	270
900	275
950	285
1,000	290
1,050	295
1,100	300
1,150	305
1,200	310
1,250	315
1,300	320
1,350	325
1,400	330
1,450	335
1,500	340

RPM between 600 & 1,500 (50–1,500 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
50	80
100	105
150	125
200	140
250	155
300	165
350	175
400	185
450	195
500	205
550	210
600	220
650	225
700	235
750	240
800	245
850	255
900	260
950	265
1,000	270
1,050	275
1,100	280
1,150	285
1,200	290
1,250	295
1,300	300
1,350	305
1,400	310
1,450	315
1,500	320

RPM < 600 (50–4,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
50	75
100	95
150	110
200	125
250	140
300	150
350	160
400	165
450	175
500	185
550	190
600	200
650	205
700	210
750	220
800	225
850	230
900	235
950	240
1,000	245
1,050	250
1,100	255
1,150	260
1,200	265
1,250	270
1,300	275
1,350	280
1,400	285
1,450	285
1,500	290
1,550	295
1,600	300
1,650	305
1,750	310
1,800	315
1,850	320
1,900	320
1,950	325
2,000	330
2,050	330
2,100	335
2,150	340
2,200	340
2,250	345
2,300	350
2,350	350
2,400	355
2,450	355
2,500	360
2,550	365
2,600	365
2,650	370
2,700	370
2,750	375
2,800	375
2,850	380
2,900	380
2,950	385
3,000	390
3,050	390
3,100	395
3,150	395
3,200	400
3,250	400
3,300	405
3,350	405
3,400	410
3,450	410
3,500	415
3,550	415
3,600	420
3,650	420
3,700	425
3,750	425
3,800	425
3,850	430
3,900	430
3,950	435
4,000	435

Diesel engine exhaust

Residential grade muffler

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	28
50	125
100	170
150	205
200	235
250	260
300	285
350	310
400	320
450	340
500	360
550	380
600	390
650	410
700	420
750	430
800	450
850	460
900	470
950	480
1,000	490
1,050	510
1,100	520
1,150	530
1,200	540
1,250	550
1,300	560
1,350	570
1,400	580
1,450	590
1,500	590
1,550	600
1,600	620
1,650	620
1,700	640
1,750	640
1,800	660
1,850	660
1,900	660
1,950	680
2,000	680
2,050	700
2,100	700
2,150	700
2,200	720
2,250	720
2,300	720
2,350	740
2,400	740
2,450	740
2,500	760
2,550	760
2,600	760
2,650	780
2,700	780
2,750	780
2,800	800
2,850	800
2,900	800
2,950	820
3,000	820
3,050	820
3,100	840
3,150	840
3,200	840
3,250	860
3,300	860
3,350	860
3,400	860
3,450	880
3,500	880
3,550	880
3,600	900
3,650	900
3,700	900
3,750	900
3,800	920
3,850	920
3,900	920
3,950	920
4,000	940

Residential muffler & casing

RPM > 1,500

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	75
50	305
100	390
150	450
200	500
250	540
300	580
350	610
400	640
450	670
500	690
550	710
600	740
650	760
700	780
750	790
800	810
850	830
900	850
950	860
1,000	880
1,050	890
1,100	910
1,150	920
1,200	930
1,250	950
1,300	960
1,350	970
1,400	980
1,450	990
1,500	1,010
1,550	1,020
1,600	1,030
1,650	1,040
1,700	1,050
1,750	1,060
1,800	1,070
1,850	1,080
1,900	1,090
1,950	1,100
2,000	1,110

Fans

Centrifugal

Backward curved/inclined blade over 36 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	2
250	4
1,250	8
6,250	19
8,125	21
10,563	24
13,731	28
17,851	32
23,206	36
30,168	38
33,184	40
36,503	41
40,153	42
44,168	43
48,585	45
53,444	46
58,788	47
64,667	49
71,134	51
78,247	52
86,072	54
94,679	56
104,147	58
114,561	60
126,017	65
138,619	65
152,481	70
167,729	70
184,502	75
202,952	75
223,247	80
245,572	80
270,129	85
297,142	90
326,857	90
359,542	95
395,496	100
435,046	100
478,551	105
526,406	110
579,046	115
636,951	120
700,646	125
770,711	130
847,782	135
932,560	140
1,025,816	145
1,128,398	150
1,241,237	155
1,365,361	165
1,501,897	170
1,652,087	180
1,817,296	185
1,999,025	190
2,198,928	200
2,418,821	210
2,660,703	220
2,926,773	230
3,219,450	240
3,541,395	250
3,895,535	260
4,285,088	270
4,713,597	280
5,184,957	290
5,703,452	300
6,273,798	310
6,901,177	330
7,591,295	340
8,350,425	350
9,185,467	370

Backward curved/inclined blade under 36 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	3
250	7
1,250	15
6,250	33
8,125	37
10,563	40
13,731	43
17,851	47
23,206	51
30,168	56
33,184	58
36,503	60
40,153	65
44,168	65
48,585	70
53,444	70
58,788	75
64,667	75
71,134	80
78,247	80
86,072	85
94,679	90
104,147	90
114,561	95
126,017	100
138,619	105
152,481	105
167,729	110
184,502	115
202,952	120
223,247	125
245,572	130
270,129	135
297,142	140
326,857	145
359,542	150
395,496	160
435,046	165
478,551	170
526,406	180
579,046	185
636,951	195
700,646	200
770,711	210
847,782	220
932,560	230
1,025,816	240
1,128,398	250
1,241,237	260
1,365,361	270
1,501,897	280
1,652,087	290
1,817,296	300
1,999,025	320
2,198,928	330
2,418,821	340
2,660,703	360
2,926,773	370
3,219,450	390
3,541,395	400
3,895,535	420
4,285,088	430
4,713,597	450
5,184,957	470
5,703,452	490
6,273,798	520
6,901,177	540
7,591,295	560
8,350,425	580
9,185,467	600

Forward curved blade

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	4
250	9
1,250	19
6,250	39
8,125	43
10,563	47
13,731	51
17,851	56
23,206	65
30,168	70
33,184	70
36,503	75
40,153	75
44,168	80
48,585	85
53,444	85
58,788	90
64,667	90
71,134	95
78,247	100
86,072	105
94,679	105
104,147	110
114,561	115
126,017	120
138,619	125
152,481	130
167,729	135
184,502	140
202,952	145
223,247	150
245,572	160
270,129	165
297,142	170
326,857	180
359,542	185
395,496	195
435,046	200
478,551	210
526,406	220
579,046	230
636,951	240
700,646	250
770,711	260
847,782	270
932,560	280
1,025,816	290
1,128,398	300
1,241,237	310
1,365,361	330
1,501,897	340
1,652,087	350
1,817,296	370
1,999,025	380
2,198,928	400
2,418,821	410
2,660,703	430
2,926,773	440
3,219,450	460
3,541,395	480
3,895,535	500
4,285,088	520
4,713,597	540
5,184,957	560
5,703,452	580
6,273,798	600
6,901,177	640
7,591,295	660
8,350,425	680
9,185,467	700

Radial, forward curved blade over 40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	7
250	16
1,250	36
6,250	60
8,125	70
10,563	75
13,731	85
17,851	90
23,206	100
30,168	115
33,184	120
36,503	125
40,153	130
44,168	135
48,585	140
53,444	145
58,788	150
64,667	155
71,134	160
78,247	170
86,072	175
94,679	185
104,147	190
114,561	200
126,017	210
138,619	220
152,481	230
167,729	240
184,502	250
202,952	260
223,247	270
245,572	280
270,129	290
297,142	300
326,857	320
359,542	330
395,496	340
435,046	360
478,551	370
526,406	390
579,046	400
636,951	420
700,646	440
770,711	450
847,782	470
932,560	490
1,025,816	520
1,128,398	540
1,241,237	560
1,365,361	580
1,501,897	600
1,652,087	620
1,817,296	660
1,999,025	680
2,198,928	700
2,418,821	740
2,660,703	760
2,926,773	780
3,219,450	820
3,541,395	840
3,895,535	880
4,285,088	920
4,713,597	940
5,184,957	980
5,703,452	1,100
6,273,798	1,100
6,901,177	1,100
7,591,295	1,200
8,350,425	1,200
9,185,467	1,300

Pressure blower, radial straight blade 20–40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	15
250	34
1,250	58
1,625	65
2,113	75
2,746	80
3,570	90
4,641	100
6,034	110
7,844	120
10,197	135
13,256	150
17,232	170
22,402	190
29,123	210
37,859	240
41,645	250
45,810	260
50,391	270
55,430	280
60,973	290
67,070	300
73,777	320
81,155	330
89,270	340
98,198	360
108,017	370
118,819	390
130,701	400
143,771	420
158,148	430
173,963	450
191,359	470
210,495	490
231,545	520
254,699	540
280,169	560
308,186	580
339,004	600
372,905	620
410,195	640
451,215	680
496,336	700
545,970	720
600,567	760
660,624	780
726,686	800
799,355	840
879,290	880
967,219	900
1,063,941	940
1,170,335	980
1,287,369	1,000
1,416,106	1,100
1,557,716	1,100
1,713,488	1,200
1,884,837	1,200
2,073,320	1,200
2,280,652	1,300
2,508,717	1,300
2,759,589	1,400
3,035,548	1,400
3,339,103	1,500
3,673,013	1,500
4,040,314	1,600
4,444,346	1,600
4,888,780	n/a
5,377,659	n/a
5,915,424	n/a
6,506,967	n/a
7,157,663	n/a
7,873,430	n/a
8,660,773	n/a
9,526,850	n/a

Pressure blower, radial straight blade under 20 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	26
250	48
1,250	90
1,625	100
2,113	110
2,746	125
3,570	135
4,641	155
6,034	170
7,844	190
10,197	220
13,256	240
17,232	270
22,402	310
29,123	340
37,859	390
41,645	400
45,810	420
50,391	440
55,430	450
60,973	470
67,070	490
73,777	520
81,155	540
89,270	560
98,198	580
108,017	620
118,819	640
130,701	660
143,771	680
158,148	720
173,963	740
191,359	780
210,495	800
231,545	840
254,699	860
280,169	900
308,186	940
339,004	980
372,905	1,100
410,195	1,100
451,215	1,100
496,336	1,200
545,970	1,200
600,567	1,300
660,624	1,300
726,686	1,400
799,355	1,400
879,290	1,400
967,219	1,500
1,063,941	1,600
1,170,335	1,600
1,287,369	n/a
1,416,106	n/a
1,557,716	n/a
1,713,488	n/a
1,884,837	n/a
2,073,320	n/a
2,280,652	n/a
2,508,717	n/a
2,759,589	n/a
3,035,548	n/a
3,339,103	n/a
3,673,013	n/a
4,040,314	n/a
4,444,346	n/a
4,888,780	n/a
5,377,659	n/a
5,915,424	n/a
6,506,967	n/a
7,157,663	n/a
7,873,430	n/a
8,660,773	n/a
9,526,850	n/a

Vaneaxial

Wheel size over 40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	6
250	14
1,250	31
1,625	35
2,113	38
2,746	41
3,570	45
4,641	49
6,034	53
7,844	59
10,197	65
13,256	75
17,232	80
22,402	90
29,123	100
37,859	110
41,645	115
45,810	120
50,391	125
55,430	130
60,973	135
67,070	140
73,777	145
81,155	150
89,270	155
98,198	160
108,017	170
118,819	175
130,701	185
143,771	190
158,148	200
173,963	210
191,359	220
210,495	230
231,545	240
254,699	250
280,169	250
308,186	270
339,004	280
372,905	290
410,195	300
451,215	310
496,336	320
545,970	340
600,567	350
660,624	360
726,686	380
799,355	390
879,290	410
967,219	430
1,063,941	440
1,170,335	460
1,287,369	480
1,416,106	500
1,557,716	520
1,713,488	540
1,884,837	560
2,073,320	580
2,280,652	600
2,508,717	640
2,759,589	660
3,035,548	680
3,339,103	700
3,673,013	740
4,040,314	760
4,444,346	800
4,888,780	820
5,377,659	860
5,915,424	880
6,506,967	920
7,157,663	940
7,873,430	980
8,660,773	1,100
9,526,850	1,100

Wheel size under 40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	6
250	14
1,250	31
1,625	35
2,113	38
2,746	41
3,570	45
4,641	49
6,034	53
7,844	59
10,197	65
13,256	75
17,232	80
22,402	90
29,123	100
37,859	110
41,645	115
45,810	120
50,391	125
55,430	130
60,973	135
67,070	140
73,777	145
81,155	150
89,270	155
98,198	160
108,017	170
118,819	175
130,701	185
143,771	190
158,148	200
173,963	210
191,359	220
210,495	230
231,545	240
254,699	250
280,169	250
308,186	270
339,004	280
372,905	290
410,195	300
451,215	310
496,336	320
545,970	340
600,567	350
660,624	360
726,686	380
799,355	390
879,290	410
967,219	430
1,063,941	440
1,170,335	460
1,287,369	480
1,416,106	500
1,557,716	520
1,713,488	540
1,884,837	560
2,073,320	580
2,280,652	600
2,508,717	640
2,759,589	660
3,035,548	680
3,339,103	700
3,673,013	740
4,040,314	760
4,444,346	800
4,888,780	820
5,377,659	860
5,915,424	880
6,506,967	920
7,157,663	940
7,873,430	980
8,660,773	1,100
9,526,850	1,100

Tubeaxial – no straightening vanes

Wheel size over 40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	9
250	19
1,250	40
1,625	43
2,113	47
2,746	51
3,570	56
4,641	65
6,034	70
7,844	75
10,197	85
13,256	95
17,232	105
22,402	115
29,123	130
37,859	145
41,645	150
45,810	155
50,391	160
55,430	170
60,973	175
67,070	185
73,777	190
81,155	200
89,270	210
98,198	220
108,017	230
118,819	240
130,701	250
143,771	260
158,148	270
173,963	280
191,359	290
210,495	300
231,545	310
254,699	320
280,169	340
308,186	350
339,004	370
372,905	380
410,195	400
451,215	410
496,336	430
545,970	450
600,567	460
660,624	480
726,686	500
799,355	520
879,290	540
967,219	560
1,063,941	600
1,170,335	620
1,287,369	640
1,416,106	660
1,557,716	680
1,713,488	720
1,884,837	740
2,073,320	760
2,280,652	800
2,508,717	820
2,759,589	860
3,035,548	880
3,339,103	920
3,673,013	960
4,040,314	1,000
4,444,346	1,100
4,888,780	1,100
5,377,659	1,100
5,915,424	1,200
6,506,967	1,200
7,157,663	1,300
7,873,430	1,300
8,660,773	1,300
9,526,850	1,400

Wheel size under 40 inches

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	15
250	34
1,250	58
1,625	65
2,113	75
2,746	80
3,570	90
4,641	100
6,034	110
7,844	120
10,197	135
13,256	150
17,232	170
22,402	190
29,123	210
37,859	240
41,645	250
45,810	260
50,391	270
55,430	280
60,973	290
67,070	300
73,777	310
81,155	330
89,270	340
98,198	350
108,017	370
118,819	380
130,701	400
143,771	410
158,148	430
173,963	450
191,359	460
210,495	480
231,545	500
254,699	520
280,169	540
308,186	560
339,004	600
372,905	620
410,195	640
451,215	660
496,336	680
545,970	720
600,567	740
660,624	760
726,686	800
799,355	820
879,290	860
967,219	880
1,063,941	920
1,170,335	960
1,287,369	980
1,416,106	1,100
1,557,716	1,100
1,713,488	1,100
1,884,837	1,200
2,073,320	1,200
2,280,652	1,300
2,508,717	1,300
2,759,589	1,300
3,035,548	1,400
3,339,103	1,400
3,673,013	1,500
4,040,314	1,500
4,444,346	1,600
4,888,780	1,600
5,377,659	n/a
5,915,424	n/a
6,506,967	n/a
7,157,663	n/a
7,873,430	n/a
8,660,773	n/a
9,526,850	n/a

Propeller

Q = flow rate (cfm) P = pressure (in. of water) (Q×P²)	Distance corresponding to 50 dBA (D₅₀) (m)
50	40
250	70
1,250	135
1,625	150
2,113	165
2,746	185
3,570	210
4,641	230
6,034	260
7,844	290
10,197	320
13,256	360
17,232	400
22,402	450
29,123	500
37,859	560
41,645	580
45,810	600
50,391	620
55,430	640
60,973	660
67,070	700
73,777	720
81,155	740
89,270	780
98,198	800
108,017	840
118,819	860
130,701	900
143,771	920
158,148	960
173,963	1,000
191,359	1,100
210,495	1,100
231,545	1,100
254,699	1,200
280,169	1,200
308,186	1,300
339,004	1,300
372,905	1,300
410,195	1,400
451,215	1,400
496,336	1,500
545,970	1,500
600,567	1,600
660,624	1,600
726,686	n/a
799,355	n/a
879,290	n/a
967,219	n/a
1,063,941	n/a
1,170,335	n/a
1,287,369	n/a
1,416,106	n/a
1,557,716	n/a
1,713,488	n/a
1,884,837	n/a
2,073,320	n/a
2,280,652	n/a
2,508,717	n/a
2,759,589	n/a
3,035,548	n/a
3,339,103	n/a
3,673,013	n/a
4,040,314	n/a
4,444,346	n/a
4,888,780	n/a
5,377,659	n/a
5,915,424	n/a
6,506,967	n/a
7,157,663	n/a
7,873,430	n/a
8,660,773	n/a
9,526,850	n/a

Flares (waste gas)

X = Q×[(V×d)/v]^a, where: Q = heating rate (Watts) V = Flare tip velocity (m/s) d = diameter of stack (m) v = gas viscosity (m²/s) a = 2.1055 "X"	Distance corresponding to 50 dBA (D₅₀) (m)
1.50E+18	35
1.88E+18	40
2.34E+18	45
2.93E+18	50
3.66E+18	55
4.58E+18	60
5.72E+18	65
7.15E+18	70
8.94E+18	75
1.12E+19	80
1.40E+19	85
1.75E+19	95
2.18E+19	100
2.73E+19	110
3.41E+19	120
4.26E+19	130
5.33E+19	145
6.66E+19	160
8.33E+19	175
1.04E+20	190
1.30E+20	210
1.63E+20	230
2.03E+20	255
2.54E+20	285
3.18E+20	315
3.97E+20	345
4.96E+20	385
6.20E+20	425
7.75E+20	470
9.69E+20	520
1.21E+21	580
1.51E+21	645
1.89E+21	715
2.37E+21	790
2.96E+21	880
3.70E+21	975
4.62E+21	n/a
5.78E+21	n/a
7.22E+21	n/a

Motors

DRPR

450–3,600 RPM (1–50 HP)

X = RPM×HP^1.33 HP = horse power RPM = rev/min "X"	Distance corresponding to 50 dBA (D₅₀) (m)
4,526	4
4,978	4
5,476	4
6,023	5
6,625	5
7,288	5
8,017	6
8,818	6
9,700	6
10,670	7
11,737	7
12,911	8
14,202	8
15,622	9
17,185	9
18,903	10
20,793	11
22,873	12
25,160	12
27,676	13
30,443	14
33,488	15
36,837	16
40,520	17
44,572	19
49,030	20
53,932	22
59,326	23
65,258	24
71,784	25
78,963	26
86,859	27
95,545	28
105,099	30
115,609	31
127,170	33
139,887	34
153,876	36
169,263	38
186,190	40
204,809	42
225,289	44
247,818	47
272,600	50
299,860	54
329,846	56
362,831	60
399,114	64
439,025	68
482,928	72
531,221	76
584,343	82
642,777	86
707,055	95
777,760	100
855,536	105
941,090	115

450–3,600 RPM (50–400 HP)

X = RPM×HP^1.5 HP = horse power RPM = rev/min "X"	Distance corresponding to 50 dBA (D₅₀) (m)
477,297	17
525,026	18
577,528	19
635,281	19
698,809	20
768,690	21
845,559	22
930,115	23
1,023,127	24
1,125,439	24
1,237,983	25
1,361,782	26
1,497,960	26
1,647,756	27
1,812,531	28
1,993,785	29
2,193,163	30
2,412,479	31
2,653,727	32
2,919,100	33
3,211,010	34
3,532,111	35
3,885,322	36
4,273,854	38
4,701,240	39
5,171,364	40
5,688,500	42
6,257,350	43
6,883,085	45
7,571,393	47
8,328,533	48
9,161,386	50
10,077,525	55
11,085,277	55
12,193,805	60
13,413,185	60
14,754,504	65
16,229,954	65
17,852,950	70
19,638,245	70
21,602,069	75
23,762,276	75
26,138,504	80
28,752,354	85
31,627,590	85
34,790,349	90
38,269,383	95
42,096,322	100
46,305,954	105
50,936,549	105
56,030,204	110
61,633,225	115
67,796,547	120
74,576,202	125
82,033,822	135

TEFC

450–3,600 RPM (1–50 HP)

X = RPM×HP^1.33 HP = horse power RPM = rev/min "X"	Distance corresponding to 50 dBA (D₅₀) (m)
5,000	9
5,499	10
6,049	11
6,654	12
7,319	12
8,051	13
8,856	14
9,742	15
10,716	16
11,788	17
12,966	19
14,263	20
15,689	21
17,258	23
18,984	24
20,882	25
22,971	26
25,268	27
27,795	28
30,574	30
33,631	31
36,995	32
40,694	34
44,673	36
49,240	38
54,164	40
59,580	42
65,538	44
72,092	47
79,301	50
87,231	55
95,954	60
105,550	60
116,105	65
127,715	70
140,487	75
154,535	75
169,989	80
186,988	90
205,686	95
226,255	100
248,881	105
273,769	115
301,146	120
331,260	130

450–3,600 RPM (50–400 HP)

X = RPM×HP^1.5 HP = horse power RPM = rev/min "X"	Distance corresponding to 50 dBA (D₅₀) (m)
477,297	33
525,026	34
577,528	35
635,281	37
698,809	38
768,690	39
845,559	41
930,115	42
1,023,127	44
1,125,439	45
1,237,983	47
1,361,782	49
1,497,960	55
1,647,756	55
1,812,531	55
1,993,785	60
2,193,163	60
2,412,479	65
2,653,727	65
2,919,100	70
3,211,010	70
3,532,111	75
3,885,322	80
4,273,854	80
4,701,240	85
5,171,364	90
5,688,500	90
6,257,350	95
6,883,085	100
7,571,393	105
8,328,533	110
9,161,386	115
10,077,525	120
11,085,277	125
12,193,805	130
13,413,185	135
14,754,504	140
16,229,954	145
17,852,950	155
19,638,245	160
21,602,069	170
23,762,276	175
26,138,504	185
28,752,354	190
31,627,590	200
34,790,349	210
38,269,383	220
42,096,322	230
46,305,954	240
50,936,549	250
56,030,204	270
61,633,225	280
67,796,547	290
74,576,202	300
82,033,822	320

Pumps

450–900 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	5
5	12
10	16
15	20
20	22
25	26
30	28
35	28
40	30
45	30
50	32
55	32
60	34
65	34
70	36
75	36
80	36
85	38
90	38
95	40
100	40

450–900 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	39
150	42
200	42
250	44
300	44
350	46
400	46
450	46
500	46
550	48
600	48
650	48
700	48
750	48
800	50
850	50
900	50
950	50
1,000	50

1,000–1,500 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	7
5	14
10	20
15	24
20	28
25	30
30	32
35	32
40	34
45	36
50	36
55	38
60	40
65	40
70	42
75	42
80	44
85	44
90	44
95	46
100	46

1,000–1,500 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	46
150	48
200	50
250	52
300	52
350	54
400	54
450	54
500	56
550	56
600	56
650	58
700	58
750	58
800	58
850	58
900	60
950	60
1,000	60

1,600–1,800 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	12
5	25
10	31
15	36
20	39
25	42
30	45
35	48
40	50
45	52
50	54
55	56
60	58
65	60
70	62
75	64
80	66
85	68
90	68
95	70
100	72

1,600–1,800 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	72
150	76
200	78
250	80
300	82
350	84
400	84
450	86
500	86
550	88
600	88
650	90
700	90
750	92
800	92
850	92
900	94
950	94
1,000	94

3,000–3,600 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	8
5	18
10	25
15	29
20	32
25	34
30	36
35	38
40	39
45	41
50	42
55	44
60	45
65	46
70	48
75	49
80	50
85	52
90	52
95	54
100	54

3,000–3,600 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	54
150	58
200	60
250	60
300	62
350	64
400	64
450	66
500	66
550	66
600	68
650	68
700	68
750	70
800	70
850	70
900	70
950	72
1,000	72

High pressure operation

1,600–1,800 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	22
5	39
10	50
15	58
20	66
25	72
30	76
35	82
40	86
45	90
50	94
55	98
60	105
65	105
70	110
75	115
80	115
85	120
90	120
95	125
100	126

1,600–1,800 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	126
150	132
200	138
250	145
300	145
350	150
400	150
450	155
500	155
550	160
600	160
650	160
700	165
750	165
800	165
850	165
900	170
950	170
1,000	170

3,000–3,600 RPM (1–100 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
1	16
5	31
10	39
15	45
20	50
25	54
30	58
35	62
40	66
45	68
50	72
55	74
60	76
65	80
70	82
75	84
80	86
85	88
90	90
95	92
100	94

3,000–3,600 RPM (100–1,000 HP)

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
100	94
150	100
200	105
250	110
300	110
350	110
400	115
450	115
500	115
550	120
600	120
650	120
700	120
750	125
800	125
850	125
900	125
950	125
1,000	130

Steam turbines

Power (HP)	Distance corresponding to 50 dBA (D₅₀) (m)
500–1,500	75
1,501–5,000	100
5,001–15,000	140

Steam valves & nearby piping

Distance corresponding to 50 dBA (D₅₀) (m)
78

Updated: August 16, 2021

Published: January 31, 2017

Footnotes

footnote[1] Back to paragraph 1 MBTU/hr = 1 MkJ/hr
footnote[2] Back to paragraph 1 MBTU/hr = 1 MkJ/hr
footnote[3] Back to paragraph 1 MBTU/hr = 1 MkJ/hr
footnote[4] Back to paragraph BHP = Boiler Horse Power; 1 BHP = 33,500 BTU/hr