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ing supports under it or to suspend it in
straps at a suitable distance from the
wall.
To prevent vibrations spreading from the
fan to the surroundings anti-vibration
mountings may be inserted between fan
and foundation. In cases where the mo-
tor is placed next to the fan, fan and mo-
tor must be mounted on a common base
frame and the anti-vibration mountings
must be mounted between base frame
and foundation.
4.2 Prior to duct connection
Prior to duct connection check that all
moving parts are able to move freely and
wherever possible with equal distance
between impeller and inlet cone
throughout the circumference. Fan and
adjacent ducts must also be clean and
free from foreign objects and substances.
4.3 Duct connection
The spread of fan vibrations to the sur-
roundings are avoided by inserting flex-
ible connections between fan and ducts.
The connections must be loosely extend-
ed, duct connections centred to inlet and
outlet fan openings and supported to
avoid overloading the flexible connec-
tions. Ducts mounted without flexible
connections must be supported so that
the weight does not affect the fan casing.
Ducts must be designed to ensure
smooth and undisturbed airflow. Avoid,
for example, sharp bends before the fan
inlet, as these can cause increased sound
levels and reduced capacity.
Inlet
d e
L e >
2.5 x d e
r >
½ d e
d e = Equivalent
Outlet
duct diameter
d e
L e >
2.5 x d e
r >
½ d e
Figure 2. Example of optimal installation
Fans with free inlets or outlets must be
fitted with wire guards according to cur-
rent regulations to prevent contact with
the impeller.
4.4 Wiring
Connection to the mains is effected by
authorized personnel. The fan must be
2
provided with a safety switch which is
switched off before working on the fan.
5. Start of operation
5.1 Prior to start of operation
Checklist prior to start of operation
– electric connections meet current reg-
ulations.
– all guards are mounted as prescribed:
Inspection door, wire guard at free in-
let and outlet openings and also drive
guard around belt drive.
– belt tension and alignment are correct
(see section 6.5).
– fans mounted on anti-vibration
mountings are able to move without
loading flexible and electric connec-
tions.
– direction of rotation of fan complies
with the arrow-plate which is checked
by short-time operation.
Motors with Y/Δ -starting
Prior to start of motor check that the re-
lay is set to the calculated time.
5.2 Starting procedure
– Start the fan.
– Check that no abnormal mechanical
noises or pulsations occur.
– Check that the vibration level is nor-
mal. This is especially important if
motor and belt drive are not assem-
bled at the factory but assembled af-
terwards. In those cases the effective
vibration speed is measured which
must not exceed 7.1 mm/s, RMS,
measured on the bearing housings.
After 30 minutes of operation check that
the fan operates normally and that the
belt drive still has the correct tension.
Important
The fan is intended for con-
tinuous operation. The following
modes of operation can cause fa-
tigue breakage in the impeller
and danger of personal injury.
- Operation in stall area
- Operation with pulsating coun-
ter pressure – called pump mode
- Operation with repeated start-
ing and stopping
If in doubt Novenco should be
contacted to assess the suitability
of the fan.
6. Maintenance
6.1 Protection prior to inspec-
tion and maintenance
When the fan is out of operation for rea-
sons of inspection or repair/mainte-
nance, the electric system must be
switched off and protected so that the fan
does not operate unintentionally.
6.2 Fan casing
The fan casing requires as standard no
maintenance other than ordinary clean-
ing.
6.3 Impeller
From the factory the impeller has been
carefully balanced in order to ensure vi-
bration-free operation. Vibrations occur-
ring during operation will normally be
due to accumulations of dust or dirt on
the impeller and will disappear after
cleaning. Should this not be the case, ex-
pert assistance should be called in imme-
diately as continued vibrations will
shorten the life of the bearings.
6.4 Motor
The motor normally only requires clean-
ing and greasing of the bearings which
should happen according to the motor
manufacturer's instructions.
6.5 Belt drive
The belt tension should be checked at
least twice a year.
Belt change and adjustment
When changing belts the motor plate
and motor respectively is lowered/loos-
ened sufficiently so that the old belts are
easy to remove and the new ones are
mounted on the belt pulleys.
If more belts are included, all belts must
be replaced at the same time. Check that
the new belts have the same tolerance
(stated on the belts). The belt drive is
tightened by making the distance be-
tween the motor belt pulley and fan belt
pulley longer which is done either by lift-
ing the motor plate again or by displac-
ing the motor. When tightening the belts
check both alignment and parallelism on
belt pulleys (see fig. 3).
Figure 3. Belt alignment and parallelism
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