18 McQuay IM 672-3
Operation Guidelines
Figure 30: Wheel-to-inlet funnel relationship—inline fans
Operating Limits
Do not exceed the operating limits in Table 7. 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 31: Torque for FC variable inlet vanes (in.–lb.)
Figure 32: Torque for AF variable inlet vanes (in.–lb.)
Table 5: 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
330 1.000
365 1.125
402 1.250
445 1.375
Table 6: 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
Overlap
Table 7: Unit sizes 003 to 035
Fan operating limits
Forward curved—housed
Dia. 9 × 4 9 × 7 9 × 9 10.62 12.62 15 18 20 22.25 24.50
Max. rpm
Class I
N/A 2189 2223 1934 1614 1328 1155 1050 944 858
Max. rpm
Class Il
2244 2854 2896 2518 2091 1725 1450 1200 1030 910
Airfoil—housed
Dia. 13.22 14.56 16.19 19.69 21.56 24.00
Max. rpm
Class I
3000 3000 2300 2000 1700 1500
Max. rpm
Class Il
4335 3918 3457 2858 2427 2255
300
250
200
150
100
90
80
Torque (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
Torque (in–lb)
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