McQuay IM 777-4
19
Operation Guidelines
Figure 29: Wheel-to-Inlet Funnel Relationship—Inline Fans
Operating Limits
Do not exceed the operating limits in
Table 8
. A fan wheel
operated beyond the rpm and temperature limits shown can
suffer permanent distortion or fracture. The resulting
unbalance can cause severe unit vibration.
Figure 30: Torque for FC Variable Inlet Vanes (in–lb)
Figure 31: Torque for AF Variable Inlet Vanes (in–lb)
Table 6: Wheel-to-Inlet Funnel Relationship—Inline Fans
Wheel—funnel overlap
Size
Overlap
150
.375
165
.438
182
.562
200
.625
222
.688
245
.750
270
.812
300
.875
Overlap
330
1.000
365
1.125
402
1.250
445
1.375
Table 7: Bearing Collar and Wheel Hub Set Screw Torque
Set screw
Minimum torque
Diameter (in)
ft/lbs
kg/m.
1/4
5.5
.76
1/16
10.5
1.45
3/8
19.0
2.63
7/16
29.0
4.01
1/2
42.0
5.81
5/8
92.0
12.72
Table 6: Wheel-to-Inlet Funnel Relationship—Inline Fans
Table 8: Unit Sizes 003 to 035
Fan operating limits
Forward curved—housed
Diameter
9 × 4
9 × 7
9 × 9
10.62
12.62
15
18
20
22.25
24.50
Maximum rpm Class I
N/A
2189
2223
1934
1614
1328
1155
1050
944
858
Maximum rpm Class Il
2700
2854
2896
2518
2091
1725
1450
1200
1030
910
Airfoil—housed
Diameter
13.22
14.56
16.19
19.69
21.56
24.00
Maximum rpm Class I
3000
3000
2300
2000
1700
1500
Maximum rpm Class Il
4335
3918
3457
2858
2427
2255
300
250
200
150
100
90
80
To
rque (in–lb)
350
400
450
500
600 650 700 750 800 850
1000
1500
Fan speed (rpm)
500
400
350
300
250
200
550
900
FC20.00
FC36.00
FC33.00
FC30.25
FC27.62
FC25.00
FC22.38
300
250
200
150
100
90
80
70
60
50
750 800 850 900
1000
1500
2000
Fan speed (rpm)
40
35
30
AF24.00
AF21.56
AF19.69
AF16.19
AF14.56
AF13.22
2500
3000
3500
4000
4500
350
400
450
To
rque (in–lb)
