20
McQuay IM 777-4
Operation Guidelines
Figure 32: Torque for FC Variable Inlet Vanes (in–lb)
Figure 33: Torque for AF Variable Inlet Vanes (in–lb)
Table 9: 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
300
250
200
150
100
90
80
70
60
50
350
400
450
500
550
600
650
700 750 800 850 900
1000
1500
2000
Fan speed (rpm)
FC22.25
FC20.00
FC18.00
FC15.00
FC12.62
FC24.50
To
rque (in–lb)
300
250
200
150
100
600
650
700 750 800 850
1000
Fan speed (rpm)
900
400
350
550
900
AF40.25
AF27.00
AF24.50
AF22.25
AF20.00
AF38.50
AF33.00
AF30.00
500
600
700
800
2000
1000
1500
1500
2000
3000
2500
Torque (in–lb)
Table 10: Operating Limits—Plenum Fans
Fan operating limits
Plenum fans
Diameter
13.5
15
16.5
18.25
20
22.25
24.5
27
30
33
36.5
40.25 44.50
49
54.25
60
Maximum rpm Class I
2895
2589
2376
2256
2077
1875
1691
1479
1328
1209
1073
972
882
799
725
651
Maximum rpm Class II
3786
3384
3100
2959
2703
2413
2199
1928
1730
1579
1401
1264
1150
1043
938
847
Maximum rpm Class III
4000
4000
3887
3735
3409
3065
2780
2423
2182
1984
1756
1598
1447
1314
1178
1071
Table 11: Operating Limits—Inline Fans, Twin Fans
Fan operating limits
Inline fans
Diameter
18.25
20
22.25
24.5
27
30
33
36.5
40.25
44.50
49
54.25
Maximum rpm Class I
2727
2488
2236
2041
1835
1665
1476
1330
1208
1072
973
880
Maximum rpm Class II
3409
3111
2796
2551
2294
2082
1846
1662
1510
1340
1216
1100
Twin fans
Diameter
9 x 9
10.62
12.62
15
18.12
20
Maximum rpm
2575
2400
2000
1700
1400
1200
Maximum HP
10
15
15
30
40
40