BCF-103 - page 6

HighTemperatureand
AltitudeFan Selection
ChicagoDesign10ATypeBCentrifugal Fans are
perfectly suited for handlinghot gases for air at high
temperatureapplications suchas induceddraft and
industrial ovens. Fans inarrangements1. 8. and9H
are capableof temperaturesup to800°Fwith the
additionof a shaft seal and shaft cooler,while
arrangement 9 (Lor R) fanshaveamaximum tem-
peratureof 650°F. All fans shouldbeoperatedwithin
themaximumRPM limits for each class and these
limits shouldbederatedpermaximumallowable
speed, Table III.
Fan capacity tables arebasedon the fanhandling
standardair at 70°Fand sea level. For operating
conditionsother than standard, correct theHPof the
fanand check the speedderating limits.
EXAMPLE:
Select a fan to handle 45,000 CFM at 5.5"
SP at 700°F and at 2000 feet altitude.
1. Refer toTable1. At 700°Fand2000 feet altitude,
the correction factor is2.35
2. Corrected SP is2.35X5.5" =13" SPat 70°Fand
sea level.
3. Using the fan rating tables, selectionof theproper
size fan isnowbasedon45,000CFMat 13" SP.
These specifications indicate that one selection
available is the size40-1/4Class IV fanwhich
shows aperformanceof 45,000CFMat 13" SP,
requiring130.7 BHPat 1495RPM.
4. To correct theBHP, divide130.7by2.35=55.61
BHP,which is the correctedBHPat 700°Fand
2000 feet altitude.
5. Verify thewheel and shaft maximum speeds
usingTable II andTable III.
a. Multiply the classmaximumwheel speed from
Table II by theClass IVWheelDerationFactor
fromTable III. Thewheelmaximum speed
@700°F is2088RPM x .86=1796RPM. Then
multiply themaximum shaft speed fromTable II
by the ShaftDerationFactor fromTable III. The
shaftmaximum speed@700°F is2088 x .94
=1963. Thus, themaximum allowable fan
speed is 1796 RPM.
b.Check the abovemaximum allowable fan
speed against the selected fan RPM. Since
the fan operating speed of 1495 RPM is
within safe limits of themaximum allow-
able of 1796 RPM, the 40-1/4 Class IV fan
will deliver 45,000 CFM at 5.5" SP, 700°F
and 2000 feet altitude requiring 55.61HP.
1.00
.99
.93
.89
.88
.86
.84
.82
.81
.79
.78
.77
.68
1.00
.99
.96
.95
.95
.94
.93
.92
.90
.88
.87
.86
.83
1.00
1.00
1,00
.99
.98
.98
.97
.97
.96
.96
.95
.94
.93
C/2,C/3 C/4
Shaft
All Cl.
70
100
200
300
350
400
450
500
550
600
650
700
800
Temp.
(F°)
TemperatureDerationFactors
22-1/4
24-1/2
27
30
33
36-1/2
40-1/4
44-1/2
49
54-1/4
60
66
73
925
836
756
687
621
1035
836
866
749
649
1165
1052
951
N.A.
N.A.
1165
1052
995
N.A.
N.A.
3800
2920
2964
2771
2529
2271
2088
1687
1682
N.A.
N.A.
N.A.
N.A.
3963
3398
3263
2831
2673
2271
2088
1820
1705
N.A.
N.A.
N.A.
N.A.
FAN
SIZE Shaft Wheel Shaft Wheel Shaft Wheel
CLASS II
CLASS III
CLASS IV
TABLE I
TEMPERATURE ANDALTITUDE CORRECTION
TABLE II – MAXIMUM RPMAT 70° F
TABLE III –
TEMPERATURE/
SPEEDDERATION
Correction factors for temperature (F) and altitude (above sea level):
standard air = .075 lbs. per cubic foot at sea level, 29.92” barometric pressure and 70° F
Note: For temperature deration only, not for air performance.
-15
0
70
100
150
200
250
300
350
400
500
600
650
700
800
.79
.87
1.00
1.06
1.15
1.25
1.34
1.43
1.53
1.62
1.81
2.00
2.09
2.19
2.38
.81
.88
1.02
1.08
1.17
1.27
1.36
1.46
1.56
1.65
1.84
2.04
2.13
2.23
2.42
.82
.90
1.04
1.10
1.19
1.29
1.39
1.49
1.58
1.68
1.88
2.07
2.17
2.27
2.48
.84
.92
1.06
1.12
1.22
1.32
1.41
1.51
1.61
1.71
1.91
2.11
2.21
2.31
2.51
.85
.93
1.08
1.14
1.24
1.34
1.44
1.54
1.64
1.75
1.95
2.15
2.25
2.35
2.56
.87
.95
1.10
1.16
1.26
1.36
1.47
1.57
1.67
1.78
1.98
2.19
2.29
2.40
2.60
.
88
.97
1.12
1.18
1.28
1.39
1.49
1.60
1.70
1.81
2.02
2.23
2.34
2.44
2.65
.90
.99
1.14
1.20
1.31
1.42
1.52
1.63
1.74
1.84
2.06
2.27
2.38
2.49
2.70
.96
1.00
1.16
1.22
1.33
1.44
1.55
1.66
1.77
1.88
2.10
2.32
2.43
2.53
2.75
1.00
1.04
1.20
1.27
1.38
1.50
1.61
1.72
1.84
1.95
2.18
2.40
2.52
2.63
2.86
AIR
TEMP
(F°)
29.92
500´
29.38
1000´
28.86
1500´
28.33
2000´
27.82
2500´
27.31
3000´
26.82
3500´
26.32
4000´
25.84
5000´
24.90
ALTITUDE (feet) withBAROMETRICPRESSURE (HG)
Refer to
ChicagoBlower’s
fan.net for performance,
fan curves and
sounddata.
For software and
assistance, contact your
local ChicagoBlower
sales engineer.
StandardWheel
• For these sizes and classes consult Chicago’s SQBFanBulletin
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