Twin City General Instructions (Fiberglass Ventilators) - IM-3000 - Manual (Page 3)

Twin City IM-3000 3
Maintenance
1. Before performing any maintenance on the fan, be
sure power is turned off and locked in the OFF
position at the service entrance.
2. Ventilators should be carefully checked at least once
a year. For critical or rugged applications, a routine
check every two or three months is suggested.
3. All motors supplied with Twin City Fan & Blower
ventilators carry a one-year warranty from date of
shipment. For repairs within the warranty period, the
motor must be taken to the motor manufacturer’s
authorized service dealer. Contact your representa-
tive for additional warranty details.
4. A periodic motor check should consist of spinning
the motor shaft with the power off to be sure the
motor turns freely and the bearings run smoothly.
The belt on belt driven units should be removed
from the motor sheave.
5. When removing or installing a belt, do not force the
belt over the sheave. Loosen the motor mount so
that the belt can be easily slipped over the
sheave.
6. The belt on belt driven units should be removed and
carefully checked for glazing, cracks, ply separation
or irregular wear. A small irregularity in the contact
surface of the belt will result in noisy operation. If
any of these defects are apparent, the belt should
be replaced. Check the sheaves also for chipping,
dents or rough surfaces which could damage the
belt.
7. The correct belt tension is important. Too tight a
belt will result in excess bearing pressure on the
motor bearings and shaft pillow blocks and may
also overload the motor. Too loose a belt will result
in slippage which will quickly “burn” out belts. A
belt should feel “live” when thumped, approximately
1 ⁄
4
" belt deflection (3 to 5 lb.) when subject to finger
pressure at midpoint between sheaves.
8. The belt alignment should also be checked to be
sure the belt is running perpendicularly to the rotat-
ing shafts. Motor and drive shafts must be parallel.
Improper alignment will result in excessive belt wear.
Table 2. Maximum Fan RPM (Belt Driven Units)
MODEL MOTOR HP
MAXIMUM
FAN RPM
1B, 2B, 3B 1/4 1680
12FA 4B 1/3 1465
5B 1/2 1675
1B, 2B, 3B 1/4 1470
14FA 4B 1/3 1620
5B 1/2 1850
1B, 2B 1/4 905
18FA 3B 1/3 995
4B 1/2 1140
1B, 2B 1/4 570
3B 1/3 625
24FA
4B 1/2 720
5B 3/4 820
6B 1 905
1B 1/3 440
2B 1/2 500
3B 3/4 575
30FA 4B 1 630
5B 1 1 ⁄
2
725
6B 2 795
1B 1/2 370
2B 3/4 425
3B 1 465
36FA 4B 1 1 ⁄
2
535
5B 2 585
6B 3 670
1B 1/2 320
2B 3/4 370
3B 1 405
40FA 4B 1 1 ⁄ 2 465
5B 2 510
6B 3 585
7B 5 690
MODEL MOTOR HP
MAXIMUM
FAN RPM
1B, 2B, 3B 1/4 1420
14WA 4B 1/3 1560
5B 1/2 1790
1B, 2B 1/4 900
18WA 3B 1/3 990
4B 1/2 1135
1B, 2B 1/4 560
3B 1/3 615
24WA 4B 1/2 705
5B 3/4 810
6B 1 890
1B 1/3 435
2B 1/2 500
3B 3/4 575
30WA 4B 1 630
5B 1 1 ⁄
2
720
6B 2 790
1B 1/2 365
2B 3/4 420
3B 1 460
36WA 4B 1 1 ⁄
2
525
5B 2 580
6B 3 660
7B 5 785
1B 1/2 315
2B 3/4 360
3B 1 395
40WA 4B 1 1 ⁄ 2 450
5B 2 495
6B 3 570
7B 5 675
8B 7 1 ⁄ 2 765
WARNING: Especially check three-phase units for rotation.
For three-phase, rotation can be changed by interchang-
ing any two of the three line leads. If the unit is checked
on temporary wiring, it should be rechecked when per-
manently installed. Motor burn-out or tripped overload
protection devices are usually the result of wrong rotation.
5. Electrical Input Check: Perform check of fan ampere
draw and verify that motor nameplate amps are not
exceeded. Take account of the service factor range if
motor is nameplated above a 1.0 service factor.
6. Fan RPM Check: Fan RPM should be checked and
verified with a tachometer. Refer to Table 2 for maxi-
mum fan RPM values.
The fan should not need balancing, as it was balanced
at the factory to be within stringent vibration levels
before shipment. However, there are several things that
may cause vibration such as rough handling in shipment
and erection, weak foundations and alignments.