Product manual

40 McQuay IM 782-4
Operation Guidelines
8 Check that condensate drain is trapped.
9 Rotate shaft by hand to be sure it is free.
10 Fan startup: Fan should start and run. Observe the
rotation. If the fan is operating backward, reverse two
legs of the three-phase supply power.
Note: Variable pitch fan drives are usually provided for
operation in the mid-speed adjustment range. However,
the drives usually ship with the adjustment opened for
minimum fan speed. Adjust the drives for the proper
airflow. See “Fan Drive Adjustments” on page 24.
After first 48 hours of operation:
1 Disconnect and lockout electrical power source.
2 Check tightness of all bearing, wheel, and sheave
setscrews (or capscrews). See Table 3.
3 Recheck belt tension and adjust if necessary. Belts
tensioned sufficiently to slip one to two seconds at
startup will perform satisfactorily, extending life and
reducing vibration. If retensioning is necessary, be
certain to retain sheave alignment.
Operating Limits
Do not exceed the operating limits in Table 6. A fan wheel that
is operated beyond the rpm and temperature limits shown may
suffer permanent distortion or fracture. The resulting
unbalance may cause severe unit vibration.
Fan Vibration Levels
Each unit as shipped is trim balanced to operate smoothly. To
provide satisfactory operation after shipping and installation,
use the accepted industry guidelines for field balancing fans.
Vibration  0.20 in/sec.
Note: Excessive vibration from any cause contributes to
premature fan and motor bearing failure. Monitor overall
vibration levels every six months of operation. An
increase in levels is an indication of potential trouble.
Vibration Causes
1 Wheel imbalance
a Dirt or debris on wheel blades
b Loose setscrews in wheel hub or bearing-to-shaft
c Wheel distorted from overspeed
2 Bent shaft
3 Drive faulty
a Variable pitch sheaves—Axial and radial runout of
flanges, uneven groove spacing, out of balance. Also
similar faults in driven sheave.
b Bad V-belts, lumpy or mismatched, belt tension too
tight or too loose
4 Bad bearings, loose bearing hold-down bolts
5 Motor imbalance
6 Fan section not supported evenly on foundation
Table 29: Bearing Collar and Wheel Hub Setscrew Torque
Setscrew Minimum torque
Diameter (inches) 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
Table 30: Fan Operating Limits
Forward curved—housed
Diameter 7 × 7 9 × 9 10 × 10 12 × 12
Twin
10"
Twin
12"
Twin
15"
Maximum
rpm
2680 2650 2100 1700 2100 1700 1500