4
6.3 Impeller
From the factory the impeller is supplied
with the blades adjusted to the pitch cor-
responding to the desired operating
point (pressure and air flow) at the fan
speed in question. To ensure vibration
free operation the impeller has been
carefully balanced in this position.
Vibrations occurring during operation
will normally be due to accumulations of
dust or dirt on the hub and blades, and
will disappear after cleaning. Should this
not be the case, expert assistance should
be called in immediately, as continued
vibrations will shorten the life of the mo-
tor bearings.
6.4 Motor
The motor normally only requires main-
tenance of the bearings as indicated in
the maintenance instructions for electric
motors.
6.5 Dismounting of motor for
types
ACN-smoke (see fig. 5)
Prior to commencing the work, switch
off the current and disconnect the motor
cable. Next, dismount any ducts on the
fan inlet and outlet sides. Remove the
impeller centre screw (see item 01), cen-
tre disc (see item 02) and hub cover (see
item 03).
Dismount the impeller by means of a
puller fastened in the 2 threaded holes of
the hub boss/threaded holes for puller
(see item 05).
Detach the motor by loosening the
screws in the motor shell (see item 06).
Now the motor (see item 11) and motor
flange (see item 10) can be removed.
In dismounting and disassembling the
fan be careful not to expose the individu-
al parts to shocks etc. likely to damage
the motor bearings or other fan compo-
nents.
6.6 Mounting of motor for types
ACN-smoke (see fig. 5)
After servicing remount the motor, take
care that the motor flange (item 10) is cor-
rectly located and that the motor shaft is
concentrically placed in the fan casing
before tightening the bolts (item 06).
Mount the impeller (item 04) on the mo-
tor shaft by means of a tool fastened in
the threaded hole of the motor shaft.
Fix the impeller hub to rest against the
motor shaft collar.
Check that the blade clearance of the im-
peller is the same throughout the circum-
ference of the casing. If that is not the
case, adjust the motor location in the sus-
pension arrangement.
Now mount centre screw (item 01), cen-
tre disc (item 02), and hub cover (item
03). Replace lock washers/lock nuts dur-
ing fan assembly. Finally connect motor
cable (item 13) in terminal box (item 12)
and ducts, if any.
To start the fan follow the procedure de-
scribed in section 5. Start of operation.
6.7 Blade pitch adjustment
The blade pitch has been adjusted in the
factory with a special tool (mounting fix-
ture) to deliver the performance required
by the customer/order on delivery.
If the fan performance is required to be
changed it is possible to change the blade
pitch. It requires knowledge of the motor
load and the max. permissible blade
pitch on the graph as related to the motor
rating (in case of blade pitch increase).
Contact Novenco before any such ad-
justment of the blade pitch. Novenco can
supply special tools for blade pitch ad-
justment and instructions for impeller
balancing. The brochure “Blade Angle
Tool” is available on request.
Figure 5. Dismounting/mounting of axial flow fan
