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Table lists estimated sound levels (dBA) for each

size at various speeds within the fan’s normal

operating range. To determine dBA for a selected

fan, locate the intersection of the fan size and the

closest RPM.

NOTES:

1. Sound levels are based on tests conducted in accor-

dance with AMCA Standard 300.

2. Sound level computations are based on a distance of

3' from the fan’s open lnlet in a free field environment.

3. Specific octave band sound power levels and sound

pressure levels available on request.

4. Sound levels of installed fans can vary greatly from

laboratory tests.The dBA ratings are only to be used

as estimates. Any comparisons and any detailed

calculations should be based on sound power levels,

which are independent of the installation.

5. AMCA Certified Ratings Seal applies to air perform-

ance only.

8-3/4

10

12-1/4

13-1/2

15

16-1/2

18-1/4

20

22-1/4

24-1/2

27

30

33

36-1/2

40-1/4

44-1/2

5000

4962

4046

3675

3302

2992

2706

2469

2155

2215

1829

1647

1413

1344

903

817

3.1

3.1

3.8

4.2

4.6

5.1

5.6

6.2

7.1

7.6

8.4

9.3

10.8

11.4

9.9

11.0

NA

NA

4280

3884

3586

3509

3173

2895

2483

2306

2087

1807

1552

1497

1179

1066

NA

NA

3.7

4.0

4.3

4.4

4.8

5.3

6.2

6.6

7.3

8.5

9.9

11.4

9.9

11.0

NA

NA

NA

NA

NA

NA

NA

3559

2943

2674

2425

2166

1970

1700

1541

1394

NA

NA

NA

NA

NA

NA

NA

4.8

5.2

5.7

6.3

7.1

7.8

9.0

9.9

11.0

FAN

SIZE RPM

RPM

RPM

Pitch Dia.*

Pitch Dia.*

Pitch Dia.*

CLASS I

CLASS II

CLASS III

8-3/4

10

12-1/4

13-1/2

15

16-1/2

18-1/4

20

22-1/4

24-1/2

27

30

33

36-1/2

40-1/4

44-1/2

FAN

SIZE 700 800 900 1000 1200 1400 1600 1800 2000 2400 2800 3200 3600

FAN SPEED - RPM

* Design Fan Sheave Pitch Diameter (inches)

50

53

56

59

62

66

69

72

75

78

44

47

50

54

57

60

63

66

69

72

75

78

81

44

47

51

54

57

60

63

66

69

72

75

78

81

85

36

40

47

50

53

56

60

62

66

69

72

75

78

81

84

87

41

45

52

55

58

61

64

67

71

74

77

80

83

86

89

92

45

49

56

59

62

65

69

71

75

78

81

84

87

90

93

49

53

59

63

66

69

72

75

78

82

85

88

91

94

52

56

63

66

69

72

75

78

82

85

88

91

94

55

59

66

69

72

75

78

81

85

88

91

94

60

64

71

74

77

80

83

86

90

93

96

64

68

75

78

81

84

88

90

94

67

72

78

82

85

88

71

75

82

85

PERCENT OF CLASS MAXIMUM

Standard Life Times 20.0

Standard Life Times 15.0

Standard Life Times 10.0

Standard Life Times 7.0

Standard Life Times 5.0

Standard Life Times 3.0

Standard Bearing Life

130

120

110

100

90

80

70

60

50

40

30

20

10

PERCENT OF DESIGN FAN

SHEAVE PITCH DIAMETER

10

20

30

40

50

60

70

80

90

100

14

Sound Levels

Minimum average bearing life is 75,000 hours.

Bearing life may be substantially increased or

decreased by variations in the operating speed

or changes in the V-belt drive. The table at right

lists the design class maximum speeds (RPM)

and fan sheave pitch diameters. The graph below

plots the increase or decrease in bearing life

when the RPM or fan sheave diameter is

changed from the values in the table.

EXAMPLE:

Determine the increased bearing life of a Size

22-1/4 Class I fan operating at 1510 RPM.

Assume the actual fan sheave pitch diameter

of 7.8".

1.

Calculate operating RPM as a percent of the

design RPM.

1510 RPM ÷ 2155 RPM = .701 x 100 =

70.1%. (Use 70%)

2.

Calculate actual fan sheave pitch diameter

as a percent of the design fan sheave pitch

diameter in the table.

7.8" ÷ 7.1" = 1.1 x 100 = 110%

3.

Locate the intersection of 70% of design

RPM and 110% of design fan sheave pitch

diameter in the graph. Increased bearing life

is 10 times the design minimum bearing life

or 750,000 hours minimum average life.

Bearing Life