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Ductwork
The ductwork dimensions should be determined in accor-
dance with the air flow to be carried, and the available static
pressure of the unit. The different air flows and power input
values for each unit are shown in the fan performance curves.
It is recommended to observe the following considerations:
a)
Whatever type of ductwork is used, it should not be
made of materials which are flammable, or which give
off toxic gases in the event of a fire. The internal sur-
faces should be smooth, and not contaminate the air
which passes through.
b) At the points where the ducts join the unit, it is recom-
mended to use flexible connections which absorb
vibrations, prevent noise inside the ductwork and allow
access to the unit (see Fig. 19).
c)
Bends near the unit outlet should be avoided as much
as possible. If unavoidable, they should be as slight as
possible, and internal deflectors should be used when
the duct has large dimensions.
d) The installation of baffles in the supply air outlet ducts
significantly dampens the noise created by the air flow.
e)
The ratio between the duct sides should not exceed
1:3 (rectangular ducts).
Fig. 19 - Side view
Flexible joint
Return
air
f)
Adjust the belts and pulleys to obtain air flows and
static pressures that differ from the nominal values, if
required.
The units are factory-set to supply nominal air flow and
nominal static pressure, as shown in the fan performance
curves.
When indoor pressure and air flow requirements differ
from nominal ratings, the motor pulley can be adjusted for
different available static pressure values:
1.
Move the motor along its track in order to remove the
belt (see Fig. 0).
.
Loosen the pulley setscrews and rotate as necessary
(see fan performance curves).
3.
Tighten the setscrews.
4.
Replace the belt(s) in the channel of the pulley.
.
Tighten the belt(s), using the tension screw nut and
washer (see Fig. 1).
6.
Check the new fan speeds with a tachometer.
7.
After the first operating hours, check the belt tension
and if necessary retighten the belts (see Fig. 1).
18
Motor pulley
Motor
Align the pulleys using a ruler.
Supply
air
Unit
To align fan and motor pulleys:
1.
Loosen fan pulley setscrews. Slide fan pulley along the
pulley shaft and align with the motor using a ruler,
making sure that it is parallel to the belt (see Fig. 1).
.
Tighten the fan pulley setscrews.
To adjust the belt tension, loosen the motor mounting
plate bolts and slide the motor mounting plate until the
belt is tight.
3.
Belt tension (see Fig. )
The minimum belt deflection is 10 mm when the force
shown in Fig. is applied.
Fig. 20
Motor support
Setscrews
Belt
Tensioning screw
Fig. 21
Legend
1
Fixed flange
2
Setscrews
3
Movable flange
4
Straight-edge must be parallel with belt
5
Motor and fan shafts must be parallel
6
Pulleys
7
Motor and fan shafts must be parallel
Fig. 22
2 kg or 3 kg
Motor
pulley
Fan pulley
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