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ENG
DATA
7697 Snider Road, Mason, OH 45040-9135
Telephone: 513-573-0600
Visit us at www.cincinnatifan.com for more information.
Catalog ENG-409 Supersedes ENG-203
TABLE OF CONTENTS
PAGE
PAGE
I. Terms and Definitions . . . . . . . . . . . . . . . . . . . . .2
XI. Typical Entrance Losses . . . . . . . . . . . . . . . . . . . . . 10
II. Fan Arrangements . . . . . . . . . . . . . . . . . . . . . . . .3
XII. Good Duct Installation Guidelines. . . . . . . . . . . . . . 10
III. Rotation and Discharge Designations . . . . . . . . .3
XIII. Estimating Static Pressure (10 to 2000 CFM) . . . . . . 11
IV. Wheel Types . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
XIV. Estimating Static Pressure (1000 to 100,000 CFM) . . 12
V. Fan Laws and Formulas . . . . . . . . . . . . . . . . . . . .4
XV. Noise Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VI. Temperature and Altitude Conversions . . . . . . . .5
XVI. Belt Drive Losses . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VII. Material Conveying . . . . . . . . . . . . . . . . . . . . . .6-7
XVII. Area and Circumference of Circles . . . . . . . . . . . . . 14
VIII. Ventilation Guidelines (Air Changes) . . . . . . . . . .8
XVIII. English and Metric Conversions . . . . . . . . . . . . . . . 15
IX. Exhaust Hood Velocities . . . . . . . . . . . . . . . . . . .8
XIX. Decimal and Millimeter Equivalents of Fractions. . . 15
X. Duct Design Practices . . . . . . . . . . . . . . . . . . . . .9
XX. Motor Dimensions and Positions . . . . . . . . . . . . . . 16
I. TERMS AND DEFINITIONS
AHP. – Air Horsepower, is work done by the fan
expressed as horsepower.
AHP = CFM x TP
6356
BHP. – Brake Horsepower, is the horsepower absorbed by the fan.
BTU. – British Thermal Unit, is the amount of
heat required to raise one pound of water from
63˚F to 64˚F.
CFM. – Cubic Feet Per Minute, is the volume of
air moved per minute.
Capture Velocity – The air velocity at any point in
front of a hood or at the hood opening nec-essary to overcome opposing air currents and capture the contaminated air by causing it to flow
into the hood.
Conveying Velocity – The minimum air velocity
required to move or transport particles within a
duct system. Measured in feet per minute.
Drive Losses – Power lost in overcoming friction from the belt, pulley and bearing friction.
EDR. – Equivalent Direct Radiation, is the
amount of heating surface which will give off 240
BTU. per hour.
FPM. – Feet Per Minute, is the velocity of the
airstream.
Final Temperature – is the temperature of air
after passing over heating coils under specified
conditions.
Free Air Delivery – is the condition under which
a fan operates when no static pressure or resistance is present.
HP. – Horsepower, is the actual rated output of
the fan motor used.
ME. – Mechanical Efficiency, is the ratio of
horsepower absorbed (BHP) to horsepower delivered by the fan (AHP).
ME = AHP
BHP
Plenum Chamber – is an air compartment maintained under pressure to serve one or more distributing ducts.
RPM. – Revolutions Per Minute, is the number of
times the fan shaft revolves per minute.
Replacement Air – The term has been used in
the same context as supply air, make-up, and intake air. It introduces fresh outside air into a
structure to replace air exhausted from fans.
Standard Air – is air which weighs .075 pounds
per cubic foot, which is dry air at 70˚F dry bulb
with a barometric pressure of 29.92 inches of
mercury.
SE. – Static Efficiency, is expressed as
SE = CFM x SP
6356 x BHP
SP. – Static Pressure, is a measure of the force
exerted by the fan in moving air through any ventilating system.
Stall – A region of instability on a fan perfor
mance curve. Evidence of this region is a dip in
2
the performance curve, also a drop in the BHP
curve. It is caused by the separation of the air
flow from the surface of the propeller blade or
fan wheel.
Shut Off – is the point of operation where the fan
flow rate is zero.
System – The path through which air is pushed
or pulled. This normally includes ducts, coils, filter, plenum changer, etc., through which air
flows. A system can be as simple as inducing air
motion into a space or a network of ducts providing air for multiple locations.
TE. – or Total Efficiency, may be expressed as
TE = CFM x TP
6356 x BHP
TS. – Tip-Speed, is the peripheral speed in feet
per minute of a propeller tip or fan wheel at any
specified RPM.
TP. – Total Pressure, is the sum of the static
pressure (SP), and velocity pressure (VP) at any
given point in a ventilating system.
V. – Velocity, is equal to the flow rate (CFM) divided by the cross-sectional area of the air flow.
V = CFM ÷ Area (Sq. Ft.).
VP. – Velocity Pressure, is equal to the kinetic
energy per unit volume of the flowing air. It can
be calculated from the formula.
VP =
[ ]
FPM
4005
2
Transport Velocity – See Conveying Velocity.
II. FAN ARRANGEMENTS AS DEFINED BY AMCA
SW - Single Width
DW - Double Width
SI - Single Inlet
DI - Double Inlet
ARR. 1 SWSI For belt drive or
direct connecdtion. Impeller overhung. Two bearings on base.
ARR. 2 SWSI For belt drive or
direct connection. Impeller overhung. Bearings in bracket supported by fan housing.
ARR. 3 SWSI For belt drive or
direct connection. One bearing on
each side and supported by fan
housing.
ARR. 3 DWDI For belt drive or
direct connection. One bearing on
each side and supported by fan
housing.
ARR. 4 SWSI For direct drive. Impeller overhung on prime mover shaft.
No bearings on fan. Prime mover base
mounted or integrally connected.
ARR. 7 SWSI For belt drive or
direct connecdtion.Arrangement 3
plus base for prime mover.
ARR. 7 DWDI For belt drive or
direct connection.Arrangement 3
plus base for prime mover.
ARR. 8 SWSI For belt drive or
direct connecdtion.Arrangement 1
plus extended base for prime
mover.
ARR. 9 SWSI For belt drive. Impeller overhung, two bearings,
with prime mover outside base.
ARR. 10 SWSI For belt drive.
Impeller overhung two bearings,
with prime mover inside base.
III. ROTATION & DISCHARGE DESIGNATIONS
IV. WHEEL TYPES
Shrouded
Radial Blade
Clockwise
Up Blast
CW 360
Clockwise
Down Blast
CW 180
Clockwise
Top Angular Up
CW 45
Clockwise
Bottom Angular Down
CW 225
Clockwise
Top Horizontal
CW 90
Clockwise
Top Angular Down
CW 135
Clockwise
Bottom Angular Up
CW 315
Clockwise
Bottom Horizontal
CW 270
Backward
Inclined
Open Radial
Blade
Counterclockwise
Up Blast
CCW 360
Counterclockwise
Down Blast
CCW 180
Counterclockwise
Top Angular Up
CCW 45
Counter clockwise
Bottom Angular Down
CCW 225
Counterclockwise
Top Horizontal
CCW 90
Counterclockwise
Top Angular Down
CCW 135
Counterclockwise
Bottom Horizontal
CCW 270
Counterclockwise
Bottom Angular Up
CCW 315
Notes:
1. DIRECTION OF ROTATION IS DETERMINED FROM DRIVE SIDE OF FAN.
2. On single inlet fans, drive side is always considered as the side opposite fan inlet.
3. On double inlet fans with drives on both sides, drive side is that with the higher powered
drive unit.
4. Direction of discharge is determined in accordance with diagrams. Angle of discharge is
referred to the vertical axis of fan and designated in degrees from such standard reference axis. Angle of discharge may be any intermediate angle as required.
5. For fan inverted for ceiling suspension, or side wall mounting, direction of rotation and
discharge is determined when fan is resting on floor.
3
Open Paddle Wheel
(Not available from
Cincinnati Fan)
Forward Curve
(Squirrel Cage)
V. FAN LAWS AND FORMULAS
4
VI. TEMPERATURE - ALTITUDE CONVERSIONS
Fan performance tables are developed using standard air which is 70˚F.,
29.92” barometric pressure and .075 lbs. per cubic foot. Density changes
resulting from temperature or barometric pressure variations (such as
higher altitudes) must be corrected to standard conditions before selecting
a fan based on standard performance data.
The location of bearings on the fan must be considered when moving
high temperature air. Fans with bearings located in the air stream have
temperature limitations. Such fans include: circulators, propeller fans, axial
power roof ventilators, double inlet centrifugal fans and some tubeaxial
fans. Fans designed for higher temperatures have the bearings located out
of the air stream. Most single inlet centrifugal fans and centrifugal power
roof ventilators are designed in this manner. Tubeaxial fans can handle
high temperatures when there is a drive bearing tube installed in the air
stream to isolate and protect the bearings.
Temperature and/or altitude conversion factors are used in making corrections to standard conditions.
Example:
With the addition of a shaft cooler wheel or heat slinger, a centrifugal fan’s
temperature limits can be extended. The heat slinger absorbs heat from the
fan shaft while circulating air over the inboard bearing to help keep it running cool.
Select a belt driven fan to deliver 1500 CFM at 8.6” SP at 200˚F., and 7000’
altitude.
STEP 1. From the table below, conversion factor is 1.63.
STEP 2. Correct static pressure is: 1.63 x 8.6” SP = 14” SP at standard
conditions.
STEP 3. Check fan catalog for 1500 CFM at 14” SP. We select a belt driven
fan at 3456 RPM and 5.15 BHP.
STEP 4. Correct the BHP for the lighter air: 5.15 ÷ 1.63 = 3.16 BHP. A 5 HP
motor will suffice at 200˚F., and 7000’ but not at standard conditions. Special motor insulation may be required above 3500 feet altitude. Consult
Factory.
Motors:
With class A rise, an enclosed motor would be expected to have less than
15˚C extra rise. With Class F rise, an enclosed motor would be expected
to have about a 20˚C extra rise. Therefore, Class A, B, or F insulated motors could be protected to 9900 foot altitude by using next higher class of
insulation (since there is a 20˚C. difference between allowable temperature
of these classes of insulation).
Also, for high efficiency motors with 1.15 or higher service factor, derating to 1.0 service factor allows the motor to be used up to 9900 feet at
up to 40˚C. ambient. Operating AC electric motors in up to 40˚C. (104˚F.)
ambient and up to 3300 feet (1000 meters) is assumed normal. For every
330 feet (100 meters) above 3300 feet, a 1% extra temperature rise is expected. At 6600 feet, a 10% extra temperature rise is expected. At 9900
feet, a 20% extra temperature rise is expected.
The above deals with rise only. In fact, higher altitudes usually have
cooler ambient temperature which can offset reduced cooling in thinner
air, so we need to know expected ambient temperature as well as altitude
to adequately assess the application.
One caution. DC motors need to be evaluated as to brush grade for good
commutation at elevated locations due to different moisture content in the
air as well as operating temperature.
Safe Operating Speeds:
When a fan moves air at temperatures substantially above 70˚F, the safe
operating speed of the wheel and shaft could be exceeded. Most metals
become characteristically weaker at high temperatures. There are maximum operating temperatures listed in suppliers catalogs for various fan
types. The wheel or impeller speeds shown per fan size are maximum for
that fan construction and should never be exceeded.
Bearings:
The weakest part of a fan is the bearing system, whether in a pillow block
design on belt-drive fans or located within the motor on direct-drive fans.
Temperatures above the fan’s maximum operating range can break down
the lubricant in the bearing and cause the bearing to fail.
-50˚
-25˚
0˚
40˚
70˚
80˚
100˚
120˚
140˚
160˚
180˚
200˚
250˚
300˚
350˚
400˚
450˚
500˚
550˚
600˚
650˚
700˚
750˚
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
.77
.82
.87
.94
1.00
1.02
1.06
1.09
1.13
1.17
1.21
1.25
1.34
1.43
1.53
1.62
1.72
1.81
1.91
2.00
2.10
2.19
2.28
.79
.84
.89
.96
1.02
1.04
1.08
1.12
1.15
1.19
1.23
1.27
1.36
1.46
1.56
1.65
1.75
1.85
1.94
2.04
2.14
2.23
2.33
.80
.85
.91
.98
1.04
1.06
1.10
1.14
1.18
1.22
1.26
1.29
1.39
1.49
1.59
1.69
1.79
1.88
1.98
2.08
2.18
2.27
2.37
.81
.87
.92
1.00
1.06
1.08
1.12
1.16
1.20
1.24
1.28
1.32
1.42
1.52
1.62
1.72
1.82
1.92
2.02
2.12
2.22
2.32
2.42
.83
.89
.94
1.02
1.08
1.10
1.14
1.18
1.22
1.26
1.30
1.34
1.45
1.55
1.65
1.75
1.86
1.96
2.06
2.16
2.26
2.36
2.47
.85
.91
.96
1.04
1.10
1.12
1.16
1.20
1.25
1.29
1.33
1.37
1.47
1.58
1.68
1.79
1.89
1.99
2.10
2.20
2.31
2.41
2.51
.86
.92
.98
1.06
1.12
1.14
1.19
1.23
1.27
1.31
1.36
1.40
1.50
1.61
1.72
1.82
1.93
2.03
2.14
2.24
2.35
2.46
2.56
.88
.94
.99
1.08
1.14
1.16
1.21
1.25
1.29
1.34
1.38
1.42
1.53
1.64
1.75
1.85
1.96
2.07
2.18
2.29
2.40
2.50
2.61
.89
.95
1.01
1.10
1.16
1.19
1.23
1.28
1.32
1.36
1.41
1.45
1.56
1.67
1.78
1.89
2.00
2.11
2.22
2.33
2.44
2.55
2.66
.91
.97
1.03
1.12
1.18
1.21
1.25
1.30
1.34
1.39
1.43
1.48
1.59
1.70
1.81
1.93
2.04
2.15
2.26
2.38
2.49
2.60
2.71
.92
.98
1.05
1.14
1.20
1.23
1.28
1.32
1.37
1.42
1.46
1.51
1.62
1.74
1.85
1.96
2.08
2.19
2.30
2.42
2.54
2.65
2.76
.94
1.01
1.06
1.16
1.22
1.26
1.30
1.35
1.40
1.44
1.49
1.54
1.65
1.77
1.88
2.00
2.12
2.23
2.35
2.47
2.58
2.70
2.81
.96
1.03
1.09
1.19
1.25
1.28
1.33
1.38
1.42
1.47
1.52
1.57
1.68
1.80
1.92
2.04
2.16
2.28
2.40
2.50
2.63
2.75
2.87
.98
1.05
1.10
1.21
1.27
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.71
1.84
1.96
2.08
2.20
2.32
2.44
2.56
2.68
2.80
2.92
1.00
1.07
1.13
1.23
1.30
1.33
1.38
1.43
1.48
1.53
1.58
1.63
1.74
1.87
2.00
2.12
2.24
2.36
2.49
2.61
2.74
2.86
2.98
1.02
1.09
1.15
1.26
1.32
1.36
1.41
1.46
1.51
1.56
1.61
1.66
1.78
1.91
2.04
2.16
2.29
2.41
2.54
2.66
2.79
2.91
3.04
1.04
1.11
1.17
1.28
1.35
1.38
1.43
1.48
1.54
1.59
1.64
1.69
1.82
1.94
2.07
2.20
2.33
2.46
2.58
2.71
2.84
2.97
3.10
1.06
1.13
1.19
1.30
1.37
1.41
1.46
1.51
1.57
1.62
1.67
1.72
1.85
1.98
2.11
2.25
2.38
2.51
2.63
2.77
2.90
3.03
3.16
5
9000 10000 11000 12000
1.08
1.15
1.22
1.32
1.40
1.43
1.48
1.53
1.58
1.64
1.70
1.75
1.88
2.00
2.14
2.27
2.41
2.54
2.68
2.80
2.94
3.06
3.19
1.12
1.20
1.26
1.36
1.45
1.48
1.54
1.58
1.65
1.70
1.75
1.81
1.94
2.08
2.22
2.35
2.50
2.62
2.77
2.90
3.04
3.18
3.31
1.16
1.24
1.31
1.41
1.51
1.56
1.60
1.66
1.72
1.78
1.84
1.89
2.02
2.16
2.31
2.47
2.61
2.75
2.90
3.04
3.19
3.33
3.47
1.21
1.29
1.37
1.47
1.57
1.61
1.66
1.72
1.78
1.84
1.90
1.96
2.10
2.25
2.40
2.55
2.70
2.85
3.00
3.14
3.30
3.44
3.59
VII. MATERIAL CONVEYING
Bulky materials such as those shown in Table 1, page 7, can be conveyed pneumatically using a Cincinnati Fan “RBE” series exhauster. Follow
the steps below to determine the fan best suited for your application.
EXAMPLE: Assume a requirement to move 2400 pounds per hour of barley through 200 feet of straight, horizontal, round duct.
NOTE: For each 90˚ elbow in your duct system, add 20 feet of straight duct to determine total equivalent straight duct length.
For each 10 feet of vertical duct, add 10 feet to your total straight duct length.
I. Convert pounds per hour to pounds per minute: 2400 lbs/hr ÷ 60 = 40 lbs/min
II. Refer to Table 1, page 7. Find “barley” under material (column A) and read horizontally. Barley weighs 38 pounds per cubic foot
(column B), requires 38 CFM of air per pound of material (column C) and a minimum of 5000 feet per minute conveying veloc-ity
(column D).
III. Determine the minimum cubic feet per minute (CFM) requirements:
38 (from column C)
x 40 (from step 1)
1520 Total minimum CFM required @ 5000 ft/min conveying velocity (column D)
IV. Determine the system duct size and system static pressure requirements from Table 2, page 7. Read across the 5000 ft/min velocity line to the 8” duct size column since this is the first (smallest) duct size column over 1520 CFM.
x
CFM/LB of Material
lbs/Minute =
We have selected 8” duct size with 1745 CFM (actual) and a velocity of 5000 ft/min.
The friction loss is 6.02” SP per 100’ x 2 = 12.04” plus 3.5” SP suction pickup (column E, Table 1) = 15.54” total system static
pressure for 200 feet of straight 8” duct.
V. Check fan rating tables for 1745 CFM at 15.54” SP at the lowest horsepower. From the RBE Industrial Exhauster catalog, we suggest a Model RBE-9. Interpolate 3499 RPM, 7.59 BHP.
VI. If material being conveyed will be going through the fan, the fan BHP can be significantly increased. The approximate increase is
calculated as:
See note 3
NOTES: 1. For each 10 feet of vertical duct, add 10 feet to your total straight duct length.
2. For equivalent losses through elbows, see chart on page 9.
3. Make sure you use correct density for location of fan.
YOUR MATERIAL CONVEYING CALCULATIONS
NOTE: If conveying long,
stringy material, be
sure to specify
open type wheel.
Consult factory.
6
XI. TYPICAL ENTRANCE LOSSES
WARNING
Ashes, Coal
Barley
Beans, Soy
Bran
Cement, Portland
Cinders, Coal
Coal, Powdered
Coffee, Beans
Cork, Ground
Corn, Cobs
Corn, Meal
Corn, Shelled
Cotton, Dry
Dust, Grinding
Fruit, Dried
Hair or Feathers, Dry
Lime, Hydrated
Malt, Dry
Oats
Plastic, Granulated
XII. GUIDELINES FOR GOOD DUCT INSTALLATIONS
Air performance ratings in fan catalogs were derived from
tests and test procedures in accordance with the latest Air
Moving and Control Association (AMCA) standards. The
test procedure used for centrifugal fans, for example,
includes a straight outlet duct and open inlet. Laboratory
test conditions are seldom, if ever, found in actual field
installations. A poor fan inlet or outlet condition will result in
an increase in system pressure losses which will reduce
the fan’s performance and decrease motor efficiency.
Increased noise levels may also be caused by certain duct
designs.
Non-ducted Bower Inlets
The open inlet of a centrifugal fan too close to a wall or
cabinet enclosure will reduce fan performance. Air is
restricted and does not have easy access to the inlet. A
minimum of one fan wheel diameter is recommended
between the fan inlet and the wall. If two fans are installed
within the same plenum or cabinet enclosure, and their
inlets face each other, their inlets should be located a minimum of two wheel diameters apart.
Inlet Duct Turns
A duct turn (elbow) too close to the fan inlet reduces the
fan’s air performance. Air enters the fan inlet unevenly
resulting in turbulence and limits the wheel’s air handling
efficiency. A minimum of one wheel diameter is recommended between the fan inlet and the end of the elbow if
turning vanes have been installed. If there are no turning
vanes in the elbow, a minimum of three wheel diameters
should separate the fan inlet and the elbow.
Open or Abrupt Discharge
When the exhaust air of a fan is discharged into an open
area, large duct, or plenum chamber, the abrupt expansion
of the air flow pattern and the sudden, reduced air velocity
creates an air turbulence that increases the system static
pressure which reduces fan performance. Up to 20% of the
air volume can be lost due to a poor outlet condition. A duct
extension with a minimum length of three times the fan
wheel diameter should be added to the fan outlet.
Duct Inlet Spin
A major cause of reduced fan performance is an inlet duct
connection that produces a spin or prerotation of the air
entering the fan inlet. Inlet spin in the same direction of the
fan wheel will reduce air volume and pressure ratings. Inlet
spin in the opposite direction of the fan rotation will substantially increase the motor horsepower requirements. An
ideal inlet condition is one which allows the air to enter the
fan axially and evenly without spin in either direction.
Discharge Duct Turns
Duct turns (elbows) located near the fan discharge should
always be in the direction of the fan rotation to minimize
duct turbulence.
Air flow is also reduced when the elbow is too close to
the fan discharge. A minimum length of 4 times the wheel
diameter of straight duct should be installed between the
fan discharge and an elbow.
10
Rags, Dry
Salt, Coarse
Sand, Dry
Sawdust, Dry
Wheat, Dry
Wood Chips, Heavy
Wood Shavings, Light
Wool, Dry
40
38
47
16
100
45
30
48
15
25
40
45
30
160-175
30
5
53-64
35
26
35
42
38
36
56
35
36
42
36
59
44
38
36
94
42
42
94
42
39
44
42
4500
5000
5200
3500
7000
6000
4000
3500
3500
5000
5500
5500
4000
5000
4000
3000
5000
4800
4500
5400
3.0
3.5
4.0
2.0
5.0
4.0
3.0
3.0
1.5
2.5
3.5
3.5
2.0
3.0
3.0
1.5
3.0
3.0
3.0
3.0
30
48
99
7-15
48
15-24
7-15
5
42
36
35
63
37
45
73
94
4500
5500
7000
3700
5800
4500
3400
5000
2.5
4.0
5.0
2.5
4.0
3.0
2.0
2.0
Whereas fans are used in
thousands of material
conveying applications
around the world, care must
be used in their selection and
location within each material
conveying system. The
material should be crushed,
shredded or pulverized
before it passes through the
fan to eliminate premature fan
housing, fan wheel and/or
bearing failure which could
cause severe personal injury
and/or complete system
failure. Please contact a
Cincinnati Fan sales engineer
in your area for correct, safe
selection for your specific
application.
2600
2800
3000
227
244
262
3.10
3.57
4.07
355
382
409
2.36
2.72
3.10
511 1.89
550 2.18
589 2.48
695 1.57
748 1.80
802 2.06
908 1.33
977 1.53
1047 1.75
1418
1527
1636
1.01
1.17
1.33
2042
2199
2356
0.81
0.93
1.07
2779
2993
3207
0.67
0.77
0.88
3630
3910
4189
0.57
0.66
0.75
4595 0.50
4948 0.57
5301 0.65
5672 0.44
6109 0.50
6545 0.57
3200
3400
3500
279
297
305
4.60
5.16
5.46
436
464
477
3.51
3.93
4.16
628 2.81
668 3.15
687 3.33
855 2.33
909 2.61
935 2.76
1117
1187
1222
1.98
2.22
2.34
1745
1854
1909
1.50
1.69
1.78
2513
2670
2749
1.20
1.35
1.43
3421
3635
3742
1.00
1.12
1.18
4468
4747
4887
0.85
0.95
1.01
5655 0.73
6008 0.82
6185 0.87
6981 0.65
7418 0.72
7636 0.77
3600
3700
3800
314
323
332
5.76
6.06
6.38
491
505
518
4.39
4.62
4.86
707 3.51
726 3.70
746 3.89
962 2.91
989 3.06
1016 3.22
1257
1292
1326
2.47
2.60
2.74
1963
2018
2073
1.88
1.98
2.09
2827
2906
2985
1.51
1.59
1.67
3848
3955
4062
1.25
1.32
1.38
5027
5166
5306
1.06
1.12
1.18
6362 0.92
6538 0.97
6715 1.02
7854 0.81
8072 0.85
8290 0.90
4000
4200
4400
349
367
384
7.03
7.72
8.43
545
573
600
5.36
5.88
6.42
785 4.29
825 4.71
864 5.14
1069
1122
1176
3.55
3.90
4.26
1396
1466
1536
3.02
3.31
3.62
2182
2291
2400
2.30
2.52
2.76
3142
3299
3456
1.84
2.02
2.21
4276
4490
4704
1.53
1.67
1.83
5585
5864
6144
1.30
1.42
1.55
7069 1.12
7422 1.23
7775 1.35
8727 0.99
9163 1.08
9599 1.18
4500
4800
5000
393
419
436
8.80
9.94
10.75
614
654
682
6.70
7.57
8.19
884 5.36
942 6.06
982 6.55
1203
1283
1336
4.44
5.02
5.43
1571
1676
1745
3.78
4.27
4.61
2454
2618
2727
2.88
3.25
3.51
3534
3770
3927
2.30
2.60
2.81
4811
5131
5345
1.91
2.16
2.33
6283
6702
6981
1.62
1.83
1.98
7952 1.40
8482 1.59
8836 1.72
9817 1.23
10472 1.40
10908 1.51
5200
5500
5600
454
480
489
11.58
12.88
13.33
709
750
764
8.82
9.81
10.15
1021
1080
1100
1390
1470
1497
5.85
6.51
6.73
1815
1920
1955
4.97
5.53
5.72
2836
3000
3054
3.79
4.21
4.36
4084
4320
4398
3.03
3.37
3.49
5559
5880
5986
2.51
2.79
2.89
7261
7679
7819
2.13
2.37
2.46
9189 1.85
9719 2.06
9896 2.13
11345 1.63
11999 1.81
12217 1.87
5800
6000
7000
506
524
611
14.25
15.20
20.37
791
818
954
10.85
11.57
15.51
1139 8.69
1178 9.27
1374 12.42
1550 7.20
1604 7.68
1871 10.29
2025
2094
2443
6.12
6.52
8.74
3163
3272
3818
4.66
4.97
6.66
4555
4712
5498
3.73
3.98
5.33
6200
6414
7483
3.09
3.30
4.42
8098
8378
9774
2.63 10249 2.27
2.80 10603 2.43
3.75 12370 3.25
12654 2.00
13090 2.13
15272 2.86
7.06
7.85
8.13
7
VIII. AVERAGE AIR CHANGES REQUIRED FOR GOOD VENTILATION
Type
Minutes
Per Change
Assembly Halls . . . . . . . . . . . . .2-10
Auditoriums . . . . . . . . . . . . . . .2-10
Bakeries . . . . . . . . . . . . . . . . . . .2-3
Boiler Rooms . . . . . . . . . . . . . . .1-5
Bowling Alleys . . . . . . . . . . . . .2-10
Churches . . . . . . . . . . . . . . . . .5-15
Dairies . . . . . . . . . . . . . . . . . . . .2-5
Dance Halls . . . . . . . . . . . . . . .2-10
Dry Cleaners . . . . . . . . . . . . . . .1-5
Minutes
Per Change
Type
Engine Rooms . . . . . . . . . . . . . .1-3
Factories . . . . . . . . . . . . . . . . . . .2-5
Forge Shops . . . . . . . . . . . . . . . .2-5
Foundries . . . . . . . . . . . . . . . . . .1-5
Garages . . . . . . . . . . . . . . . . . .2-10
Generator Rooms . . . . . . . . . . . .2-5
Gymnasiums . . . . . . . . . . . . . .2-10
Kitchens - Hospital . . . . . . . . . . .2-5
Kitchens - Restaurant . . . . . . . . .1-3
Type
Laboratories . . . . . . . . . . . . . . . .1-5
Laundries . . . . . . . . . . . . . . . . . .1-3
Offices . . . . . . . . . . . . . . . . . . .2-10
Packing Houses . . . . . . . . . . . . .2-5
Plating Rooms . . . . . . . . . . . . . .1-5
Toilets . . . . . . . . . . . . . . . . . . . . .2-5
Transformer Rooms . . . . . . . . . .1-5
Warehouses . . . . . . . . . . . . . . .2-10
IX. RECOMMENDED VELOCITIES FOR EXHAUST HOODS
8
Minutes
Per Change
X. DUCT DESIGN PRACTICES
*
3”
4
5
6
7
8
10
12
14
16
18
20
24
30
36
40
48
5
6
9
12
13
15
20
25
30
36
41
46
57
74
93
105
130
3
4
6
7
9
10
14
17
21
24
28
32
40
51
64
72
89
3
4
5
6
7
8
11
14
17
20
23
26
32
41
52
59
73
4”
6”
8”
10”
12”
14”
16”
18”
20”
24”
28”
30”
32”
* Turn Ratio = No. of duct diameters
9
3’
5’
7’
9’
11’
13’
16’
18’
20’
24’
28’
31’
33’
5’
7’
11’
14’
17’
21’
25’
28’
32’
37’
46’
49’
53’
XI. TYPICAL ENTRANCE LOSSES
XII. GUIDELINES FOR GOOD DUCT INSTALLATIONS
Air performance ratings in fan catalogs were derived from
tests and test procedures in accordance with the latest Air
Moving and Control Association (AMCA) standards. The test
procedure used for centrifugal fans, for example, includes a
straight outlet duct and open inlet. Laboratory test conditions
are seldom, if ever, found in actual field installations. A poor
fan inlet or outlet condition will result in an increase in system pressure losses which will reduce the fan’s performance
and decrease motor efficiency. Increased noise levels may
also be caused by certain duct designs.
Non-ducted Bower Inlets
The open inlet of a centrifugal fan too close to a wall or cabinet enclosure will reduce fan performance. Air is restricted
and does not have easy access to the inlet. A minimum of
one fan wheel diameter is recommended between the fan
inlet and the wall. If two fans are installed within the same
plenum or cabinet enclosure, and their inlets face each
other, their inlets should be located a minimum of two wheel
diameters apart.
Inlet Duct Turns
A duct turn (elbow) too close to the fan inlet reduces the
fan’s air performance. Air enters the fan inlet unevenly resulting in turbulence and limits the wheel’s air handling efficiency. A minimum of one wheel diameter is recommended
between the fan inlet and the end of the elbow if turning
vanes have been installed. If there are no turning vanes in
the elbow, a minimum of three wheel diameters should separate the fan inlet and the elbow.
Open or Abrupt Discharge
When the exhaust air of a fan is discharged into an open
area, large duct, or plenum chamber, the abrupt expansion
of the air flow pattern and the sudden, reduced air velocity
creates an air turbulence that increases the system static
pressure which reduces fan performance. Up to 20% of the
air volume can be lost due to a poor outlet condition. A duct
extension with a minimum length of three times the fan
wheel diameter should be added to the fan outlet.
Duct Inlet Spin
A major cause of reduced fan performance is an inlet duct
connection that produces a spin or prerotation of the air entering the fan inlet. Inlet spin in the same direction of the fan
wheel will reduce air volume and pressure ratings. Inlet spin
in the opposite direction of the fan rotation will substantially
increase the motor horsepower requirements. An ideal inlet
condition is one which allows the air to enter the fan axially
and evenly without spin in either direction.
Discharge Duct Turns
Duct turns (elbows) located near the fan discharge should
always be in the direction of the fan rotation to minimize duct
turbulence.
Air flow is also reduced when the elbow is too close to the
fan discharge. A minimum length of 4 times the wheel diameter of straight duct should be installed between the fan
discharge and an elbow.
10
XIII. ESTIMATING STATIC PRESSURE - 10 to 2000 CFM
ROUND DUCT FRICTION CHART
.01
.02
.03 .04 .06 .08 .1
.2
.3
.4
.6
.8 1
2
3
4
6
8 10
.01
.02
.03 .04 .06 .08 .1
.2
.3
.4
.6
.8 1
2
3
4
6
8 10
2000
1000
900
800
700
600
500
CU. FT. OF AIR PER MINUTE
400
300
200
100
90
80
70
60
50
40
30
20
10
FRICTION LOSS IN INCHES OF WATER PER 100 FT.
11
XIV. ESTIMATING STATIC PRESSURE - 1000 to 100,000 CFM
ROUND DUCT FRICTION CHART (Continued)
.01
.02 .03 .04
.06 .08 .1
.2
.3
.4
.6
.8 1
2
3 4
6
8 10
.01
.02 .03 .04
.06 .08 .1
.2
.3
.4
.6
.8 1
2
3 4
6
8 10
100,000
90,000
80,000
70,000
60,000
50,000
40,000
30,000
CU. FT. OF AIR PER MINUTE
20,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
FRICTION LOSS IN INCHES OF WATER PER 100 FT.
12
XV. NOISE FACTORS
This section includes a general list of good practices to follow when selecting and installing fans to minimize the noise
produced from their operation.
3. When two sizes of the same fan type deliver the same
air volume, select the larger size running at a slower
speed.
Check list for quiet operation:
1. Design the fan system for minimum resistance to air flow.
Regardless of the type of fan used, sound generation increases with increases in static pressure.
4. Use vibration isolators and pads for fans and ductwork
suitable for the application.
5. Avoid transmitting noise through a duct system. For general ventilation, inlet or outlet duct runs should not be directly connected to the fan. Isolate the connection with
a rubber gasket. Whenever possible, leave a 1” gap between the fan and duct. Cover the gap with canvas or
other suitable material to prevent air leaks.
a. Use larger heating or cooling coils, larger filter
areas and larger size ducts.
b. Avoid abrupt changes in air velocity by using long
transition pieces when changing to another size
duct.
c. Avoid abrupt changes in direction of air flow by minimizing the number of turns in the duct run. If turns
are required, use an elbow with a large turn radius
and turning vanes. Minimum elbow radius should
be equal to twice the duct diameter.
d. Make all duct runs as short and direct as possible.
e. Avoid elbows less than 4 wheel diameters away
from fan discharge or less than 2 wheel diameters
away from fan inlet.
6. Avoid mechanical noise.
a. Tighten or strengthen vibrating panels.
b. Keep bearings lubricated.
c. Tighten belt(s) to proper tension. Do not
overtighten.
d. Align pulleys and shafts. Motor and fan shaft must
be parallel.
e. Tighten the setscrews in the wheel or impeller to
their proper torque setting.
f. Keep fan blades and wheels clean.
7. Locate fans away from people and the work area. Consider roof mounting.
2. Select a fan type suitable for the application.
XVI. APPROXIMATE BELT DRIVE LOSSES
13
XVII. AREA AND CIRCUMFERENCE OF CIRCLES
AND SIDES OF SQUARES OF EQUAL AREAS
.7854
3.142
7.069
12.57
19.63
.0054
.0218
.0491
.0873
.1364
3.14
6.28
9.42
12.57
15.71
.2618
.5236
.7854
1.047
1.309
.89
1.77
2.66
3.54
4.43
51
52
53
54
55
2043
2124
2206
2290
2376
14.19
14.75
15.32
15.90
16.50
160.2
163.4
166.5
169.6
172.8
13.35
13.61
13.88
14.14
14.40
45.20
46.08
46.97
47.86
48.74
6
7
8
9
10
28.27
38.48
50.27
63.62
78.54
.1964
.2673
.3491
.4418
.5454
18.85
21.99
25.13
28.27
31.42
1.571
1.833
2.094
2.356
2.618
5.32
6.20
7.09
7.98
8.86
56
57
58
59
60
2463
2552
2642
2734
2827
17.10
17.72
18.35
18.99
19.63
175.9
179.1
182.2
185.4
188.5
14.66
14.92
15.18
15.45
15.71
49.63
50.51
51.40
52.29
53.17
11
12
13
14
15
95.03
113.1
132.7
153.9
176.7
.6600
.7854
.9218
1.069
1.277
34.56
37.70
40.84
43.98
47.12
2.880
3.142
3.403
3.665
3.927
9.75
10.63
11.52
12.40
13.29
61
62
63
64
65
2922
3019
3117
3127
3318
20.29
20.97
21.65
22.34
23.04
191.6
194.8
197.9
201.1
204.2
15.97
16.23
16.49
16.76
17.02
54.06
54.91
55.83
56.72
57.60
16
17
18
19
20
201.0
227.0
254.7
283.5
314.2
1.396
1.576
1.767
1.969
2.182
50.26
53.41
56.55
59.69
62.83
4.189
4.451
4.712
4.974
5.236
14.18
15.06
15.95
16.84
17.72
66
67
68
69
70
3421
3526
3632
3739
3848
23.76
24.48
25.22
25.97
26.73
207.3
210.5
213.6
216.8
219.9
17.28
17.54
17.80
18.06
18.33
58.49
59.38
60.26
61.15
62.04
21
22
23
24
25
346.3
380.1
415.5
452.4
490.9
2.405
2.640
2.885
3.142
3.409
65.97
69.11
72.26
75.40
78.54
5.498
5.760
6.021
6.283
6.545
18.61
19.49
20.38
21.27
22.15
71
72
73
74
75
3959
4072
4185
4301
4418
27.49
28.27
29.07
29.87
30.68
223.1
226.2
229.3
232.5
235.6
18.59
18.85
19.11
19.37
19.63
62.92
63.18
64.99
65.58
66.40
26
27
28
29
30
530.9
572.5
615.7
660.5
706.8
3.687
3.976
4.276
4.587
4.909
81.7
84.8
88.0
91.1
94.2
6.807
7.069
7.330
7.592
7.854
23.04
23.93
24.81
25.70
26.59
76
77
78
79
80
4536
4657
4778
4902
5027
31.50
32.34
33.18
34.04
34.93
238.8
241.9
245.0
248.2
251.3
19.90
20.16
20.42
20.68
20.94
67.35
68.48
69.15
70.03
70.89
31
32
33
34
35
754.7
804.2
855.3
907.9
962.1
5.241
5.585
5.940
6.305
6.681
97.4
100.5
103.7
106.9
110.0
8.116
8.378
8.639
8.901
9.163
27.47
28.36
29.25
30.13
31.02
81
82
83
84
85
5153
5281
5411
5542
5675
35.78
36.67
37.57
38.48
39.41
254.5
257.6
260.8
263.9
267.0
21.21
21.47
21.73
21.99
22.25
71.80
73.35
73.55
74.45
75.48
36
37
38
39
40
1017.8
1075.2
1134.1
1194.5
1256.6
7.069
7.467
7.876
8.296
8.727
113.1
116.2
119.4
122.5
125.7
9.425
9.686
9.948
10.21
10.47
31.90
32.79
33.68
34.56
35.45
86
87
88
89
90
5809
5945
6082
6221
6363
40.34
41.28
42.24
43.20
44.18
270.2
273.3
276.5
279.6
282.7
22.51
22.78
23.04
23.30
23.56
76.22
77.10
77.99
78.87
79.76
41
42
43
44
45
1320.2
1385.4
1452.2
1520.5
1509.4
9.168
9.621
10.08
10.56
11.04
128.8
131.9
135.1
138.2
141.4
10.73
10.99
11.26
11.52
11.78
36.33
37.22
38.11
38.99
39.88
91
92
93
94
95
6504
6648
6793
6940
7088
45.17
46.16
47.17
48.19
49.22
285.9
289.0
292.2
295.3
298.5
23.82
24.09
24.35
24.61
24.87
80.65
81.54
82.42
83.31
84.19
46
47
48
49
50
1661.9
1734.9
1809.5
1885.7
1963.5
11.54
12.05
12.51
13.09
13.64
144.5
147.7
150.8
153.9
157.1
12.04
12.30
12.57
12.83
13.09
40.76
41.65
42.58
43.42
44.31
96
97
98
99
100
7238
7390
7543
7698
7855
50.27
51.32
52.38
53.46
54.54
301.6
304.7
307.9
311.0
314.2
25.13
25.39
25.66
25.92
26.18
85.08
85.96
86.85
87.74
88.63
1
2
3
4
5
14
XVIII. ENGLISH AND METRIC CONVERSIONS
1.0
27.761
13.635
.00403
.03937
.53681
.03602
1.0
.49116
.00015
.00142
.01934
.07334
2.0360
1.0
.00030
.00289
.03937
248.36
6894.7
3386.4
1.0
9.7779
133.32
25.40
705.13
346.33
.10227
1.0
13.635
1.8628
51.715
25.40
.00750
.07334
1.0
MISCELLANEOUS
CONVERSION FACTORS
1.0
60.0
88.0
196.85
3.2808
.05468
1.0
.01667
2118.9
35.315
.58858
2.1189
.01136
.68128
1.0
2.2369
.03728
.00062
.000472
.00000787
1.0
.01667
.00028
.001
.30480
18.228
26.822
60.0
1.0
.01667
18.288
1093.7
1609.4
3600.0
60.0
1.0
METRIC PREFIXES
deci
= x .1
centi = x .01
mili
= x .001
micro = x .000001
deca = x 10
hecto = x 100
kilo
= x 1,000
mega = x 1,000,000
1.6990
.02832
3600.0
60.0
1.0
3.6
LENGTH
1 in
1 ft
1 yd
1 mi
1 nau. mi
= 2.54 cm
= .3048 m
= .9144 m
= 1.6093 Km
= 1.1516 mi
POWER
1 hp = .746 KW
1 hp = 550 ft-lb/sec
1 hp = 33000 ft-lb/min
1 hp = 76.04 kg-m/sec
1 hpm = 75.00 Kg-m/sec
AREA
1 in2
1 Ft2
1 yd2
1 mi2
1 Btu
1 hp
1 hp
1 hp
1 kw
1 Ton
= 6.4516 cm2
= .0929 m2
=.8361 m2
= 2.5899 Km2
HEAT
= 777.97 Ft-lb
= 2545 Btu/hr
= 1.014 metric hp
= .0761 boiler hp
= 3414 Btu/hr
= 12000 Btu/hr
DENSITY
1 lb/ft3 = 16.018 kg/m3
TIP SPEED
1 fpm = .0051 m/s
XIX. DECIMAL AND MILLIMETER EQUIVALENTS OF FRACTIONS
1/64 . . . . . . . . . . . . . . . . . . .
1/32 . . . . . . . . . . .
3/64 . . . . . . . . . . . . . . . . . . .
1/16 . . .
5/64 . . . . . . . . . . . . . . . . . . .
3/32 . . . . . . . . . . .
7/64 . . . . . . . . . . . . . . . . . . .
1/8 . . . .
9/64 . . . . . . . . . . . . . . . . . . .
5/32 . . . . . . . . . . .
11/64 . . . . . . . . . . . . . . . . . .
3/16 . . .
13/64 . . . . . . . . . . . . . . . . . .
7/32 . . . . . . . . . . .
15/64 . . . . . . . . . . . . . . . . . .
1/4 . . . .
17/64 . . . . . . . . . . . . . . . . . .
9/32 . . . . . . . . . . .
19/64. . . . . . . . . . . . . . . . . .
5/16 . . .
21/64 . . . . . . . . . . . . . . . . . .
11/32 . . . . . . . . . .
23/64 . . . . . . . . . . . . . . . . . .
3/8 . . . .
25/64 . . . . . . . . . . . . . . . . . .
13/32 . . . . . . . . . .
27/64 . . . . . . . . . . . . . . . . . .
7/16 . . .
29/64 . . . . . . . . . . . . . . . . . .
15/32 . . . . . . . . . .
31/64 . . . . . . . . . . . . . . . . . .
1/2 . . . .
.015625
.03125
.046875
.0625
.078125
.09375
.109375
.125
.140625
.15625
.171875
.1875
.203125
.21876
.234375
.250
.265625
.28125
.296875
.3125
.328125
.34375
.359375
.375
.390625
.40625
.421875
.4375
.451325
.46875
.484375
.500
.397
.794
1.191
1.588
1.984
2.381
2.778
3.175
3.572
3.969
4.366
4.763
5.159
5.556
5.953
6.350
6.747
7.144
7.541
7.938
8.334
8.731
9.128
9.525
9.922
10.319
10.716
11.113
11.509
11.906
12.303
12.700
33/64 . . . . . . . . . . . . . . . . .
17/32 . . . . . . . . . .
35/64 . . . . . . . . . . . . . . . . .
9/16 . . .
37/64 . . . . . . . . . . . . . . . . .
19/32 . . . . . . . . . .
39/64 . . . . . . . . . . . . . . . . .
5/8 . . . .
41/64 . . . . . . . . . . . . . . . . .
21/32 . . . . . . . . . .
43/64 . . . . . . . . . . . . . . . . .
11/16 . .
45/64 . . . . . . . . . . . . . . . . .
23/32 . . . . . . . . . .
47/64 . . . . . . . . . . . . . . . . .
3/4 . . . .
49/64 . . . . . . . . . . . . . . . . .
25/32 . . . . . . . . . .
51/64 . . . . . . . . . . . . . . . . .
13/16 . .
53/64 . . . . . . . . . . . . . . . . .
27/32 . . . . . . . . . .
55/64 . . . . . . . . . . . . . . . . .
7/8 . . . .
57/64 . . . . . . . . . . . . . . . . .
29/32 . . . . . . . . . .
59/64 . . . . . . . . . . . . . . . . .
15/16 . .
61/64 . . . . . . . . . . . . . . . . .
31/32 . . . . . . . . . .
63/64 . . . . . . . . . . . . . . . . .
1 .....
15
.515625
.53125
.546875
.5625
.578125
.59375
.609375
.625
.640625
.65625
.671875
.6875
.703125
.71875
.734375
.750
.765625
.78125
.796875
.8125
.828125
.83475
.859375
.875
.890625
.90625
.921875
.9375
.953125
.96875
.984375
1.000
13.097
13.494
13.891
14.288
14.684
15.081
15.478
15.875
16.272
16.669
17.066
17.463
17.859
18.256
18.653
19.050
19.447
19.844
20.241
20.638
21.034
21.431
21.828
22.225
22.622
23.019
23.416
23.813
24.209
24.606
25.003
25.400
XX. MOTOR DIMENSIONS AND POSITIONS
C Varies
Single Phase
Only
N
V
Motor Positions with Relation to Fan
AB
XO
O
P
U
F
F
H= Hole
diameter
D
E
BA
C Varies
AH
Single Phase
V
Only
AB
45˚
E
45˚
XO
TAP
P
AK
U
BD
AJ
AA = Conduit Size
Dimensions in inches
Highlighted dimensions are set by NEMA within each frame size. All other dimensions can vary depending on motor type and/or manufacturer.
1.5M-4/09 ADV.
16