Unit installation

McQuay IM 777-3 19
Operation Guidelines
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 28: Torque for FC Variable Inlet Vanes (in–lb) Figure 29: Torque for AF Variable Inlet Vanes (in–lb)
Table 7: 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
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)
Table 8: Unit Sizes 040 to 090
Fan operating limits
Forward curved—housed
Diameter 20 22.38 25 27.62 30.25 33 36
Maximum rpm Class I 1010 930 790 690 650 600 560
Maximum rpm Class Il 1281 1178 1011 910 835 763 715
Airfoil—housed
Diameter 20 22.25 24.5 27 30 33 36.5
Maximum rpm Class I 2077 1875 1691 1479 1328 1209 1073
Maximum rpm Class Il 2703 2413 2199 1928 1730 1579 1401