4
6.2 Fan casing
The fan casing requires no maintenance
other than ordinary cleaning.
If the fan casing is painted, the painted
surface should be checked regularly and
repaired where necessary.
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/ACW/ARN (see fig. 11)
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 (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 individ-
ual parts to shocks etc. likely to damage
the motor bearings or other fan compo-
nents.
6.6 Mounting of motor for types
ACN/ACW/ARN (see fig. 11)
After servicing remount the motor; see
that the motor flange (item 10) is correct-
ly located and that the motor shaft is con-
centrically placed in the fan casing be-
fore 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 clear-
ance of the impeller is the same through-
out the circumference of the casing. If
this is not the case, adjust the motor lo-
cation in the suspension arrangement.
Now mount the centre screw (item 01),
centre disc (item 02) and hub cover (item
03). Replace lock washers/nuts during
fan assembly. Finally, connect the motor
cable (item 13) in the terminal box (item
12) and any ducts.
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 (fixture) to de-
liver 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.
6.8 Fault localization
These are likely causes of breakdowns/
failures:
Deficiency in performance:
Blocked air supply to the fan inlet side:
- Damper closed
- Duct choked
- Supply fan, if any, stopped
- Motor defective
- Motor disconnected
- Wrong direction of rotation of impeller
Noise/vibrations:
- Bearings in electric motor defective
- Impeller out of balance
- Impeller worn/damaged
- Bolts/components loose
- Impeller blades have different pitch an-
gles
Fan operates in the stalling area. May re-
sult in breakdown. Repair failures, see
“Deficiency in performance”.
7. Sound
The sound generation of the fans de-
pends on installation and operating con-
ditions, which means that no general da-
ta of the sound generation can be given.
Refer the product catalogue, AirBox
computer program and technical fan
specifications.
8. Safety
The NovAx axial flow fans must be in-
stalled according to Novenco’s, the cur-
rent and the local safety regulations. At
a minimum these include EN 13850.
It is recommended to review and revise
safety procedures regularly.
Safety check
- Test if safety procedures and the instal-
lation work correctly.
- Check if safety regulations have been
changed and if the installation needs
revising.
- Consider taking additional measures to
improve the safety of the installation.
For example, by mounting wire guards
on inlet and outlet.
9. Spare parts
Contact Novenco for information about
and ordering of spare parts.
