VTS VENTUS PRO PVS PO 30 AC [10/34] Ducted outlet conditions

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OIMM – VENTUS PRO

With the outlet connected to the discharge duct by a exible connector, which is desirable for noise and vibration

isolation, it is important that the connector is correctly tted. The fan outlet and the duct should not be misaligned

nor should the exible connector be allowed to concertina. A smooth passage of air is desirable at all times.

When discharging into a duct of larger cross-sectional area than the fan outlet, an expansion section with an

included angle of 7-20º should be used. The ideal conguration is with parallel length

of ducting prior to the expansion section, allowing the air to become less turbulent before expanding. The fan

should never discharge directly into a duct with larger cross- section.

The same criteria apply when discharging into a duct of smaller cross-sectional area then the fan outlet.

A ducting section with an included angle of up to 45º should be used. Losses will again be minimized if a parallel

section of ducting is used prior to the reducing section. To achieve ideal conditions the length of parallel ducting

in both cases should be equal to 8 impeller diameters. However, parallel ducting of considerably shorter lengths

can be used to advantage.

! Appropriate operation of the exible connection occurs if it is stretched to about 110 mm.

! The ducts connected to the AHU have to be suspended or underpinned with dedicated support

elements. Conducting the ducts with the ttings should be done in a way to eliminate possible

increase of noise level in the ventilation system.

! Air tightness should be maintained to achieve required air ow conditions. Poor ductwork

connections to the unit and incorrect size, shape and arrangement of ductwork ttings can

change airow conditions.

DUCTED OUTLE CONNECTIONS

3.6.1

» DUCTED OUTLET CONDITIONS

» RULES DUCTED OUTLET CONNECTIONS

Extremely high losses occur when attempts are made to change the direction of the airow close to the fan

discharge. If this is necessary the installation should be carried out as in and ever as in. A better solution is to

have a parallel section of ducting prior to changing direction and it should be as long as can be accommodated.