M23740N6-03 01/10/07
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12
AIR CONNECTIONS
Proper execution and sizing of air connections are essential
for ensuring correct operation of the unit and an acceptable
level of silence in the room.
When designing and creating ducts, consider PRESSURE
DROPS, FLOW RATE and AIR SPEED which need to be
compatible with the characteristics of the unit. Special
consideration needs to be made for pressure drops that are
greater than the unit's static pressure, which would lead to
a reduction in flow rate resulting in unit shutdown.
the weight of the ducts must not be supported by the
connection flanges
place anti-vibration joints between the ducts and the
unit
the connection to the flanges and between the various
sections of the ducts must ensure an airtight seal,
preventing leakage in delivery and return which would
compromise overall system efficiency.
limit pressure drops by optimizing the path, the type
and number of curves and the branches
use curves with a wide radius. Consider whether it
might be useful to equip them with deflectors
(especially if the air speed is high or if curves are tight)
FEATURES FOR DUCTS FOR TREATED AIR
1. The inner surface of the duct must be smooth and
washable. It must not contaminate the air.
2. Thermally insulate the ducts and the flanges so as to
prevent loss of energy and condensation build-up.
Proper distribution of air in the room is essential for
ensuring comfort levels.
In the selection and positioning of grilles, outlets and
diffusers, the following are to be avoided:
3. excessive air speed
4. formation of stagnant zones and layering
5. entry of cold air into the room
6. formation of localized currents (due to uneven air
distribution)
7. excessive variations in ambient temperature in the
vertical and horizontal planes
8. short circuiting of delivery air towards return air
For purposes of comfort, the following things need to be
considered:
9. air diffusers must be selected by checking the sound
power generated at nominal flow rate conditions
10. the disconnections to the diffusers are to be made
using flexible elements
11. the return grilles must be amply sized
