Roof Space Ventilation
Commercial / Industrial
Hurricane Turbine Ventilator
Widely recognised as the most
efficient industrial ventilator available in the world today.
was the first industrial ventilator to incorporate vertical vane design
which tests at University of Technology Sydney have shown to be superior
in air handling capacity to the traditional horizontal vane design
is designed and manufactured in Australia for harsh operating conditions.
It is suitable for industrial, commercial and community buildings,
including schools. Throat sizes available include 100mm, 150mm, 225mm,
300mm, 400mm, 450mm, 500mm, 600mm, 700mm, 800mm, and 900mm.
The wind driven Hurricane
ventilator exhausts hot, stale air from buildings and allows it to be
replaced at low level with fresh air at ambient temperature. The result is
a much more pleasant and healthier working environment.
Meets the highest of
corrosion resistant aluminium, the
has been tested by Construction Research Laboratories Inc, Miami, Florida
and withstood a continuous gusting wind of 240km/hr without damage. It has
also passed the requirements of the Low Speed Dynamic Rain Penetration
Test (3L/m at 57.4km/hr).
- All aluminium construction.
- A varipitch base that suits all roof
slopes to 45° for vent sizes up to 700mm. Ridge mounting or square to
round bases available.
- Tandaco prepacked double row ball
- Vertical vanes for improved torque at
low wind speed.
- Powder coating in most popular roofing
- Eleven throat sizes.
- Cord, remote control, manual, or
electric dampers available.
- A 15 year performance warranty.
The exhausted air is replaced with fresh air at ambient temperature, which
is drawn into the building via low level louvres and doorways, thus
providing vertical air movement, which is the most natural, efficient and
predictable way to ventilate buildings.
Vertical air movement occurs due to lower density, warm air rising as it
expands becoming more buoyant. As cool air, which is dense and therefore
heavier, enters the building at low level it pushes the warm air upwards
thus developing a convection current.
The rate at which warm air rises depends on two factors:
The temperature difference between
the rising column of warmer air and the surrounding cooler air; and
The height through which the
temperature difference is generated is called the “stack height”. This
is the vertical distance between the point of entry of fresh air and the
point of exhaust at the roof ventilators.
These two thermodynamic forces were
used by early man to ventilate primitive buildings.
of natural ventilation
The Indian Teepee is a classic
example of structure employing these forces to ensure adequate
ventilation by the provision of a doorway to allow entry of fresh
air, and a hole at the top to exhaust stale air.
During the industrial revolution manufacturing buildings were
frequently full of smoke, fumes or steam.
The moist air condensed on the inside of the roof and precipitated
onto the workers below, which led to the development of elementary
ventilation devices in an attempt to overcome these problems.
These devices were either holes
in the roof with some type of elevated covering to keep the weather
out, or new styles of roof systems called Lantern or jack roofs.
They were very inefficient by modern standards as they allowed wind
to enter on the windward side causing turbulence in the opening and
preventing ANY exhaust of air from building.
The importance of wind
A well-designed turbine ventilator, like the Hurricane, takes advantage of
the wind to create a positive flow through the throat of the ventilator.
The wind influences the performance of the ventilator in two ways:
As the wind approaches and strikes the ventilator, it
jumps, creating an area of low pressure on the leeward side of the
turbine, causing a continuous extraction of air from the building.
As the turbine rotates, the centrifugal forces
associated with the rotation fling air outwards across the surface of the
vanes. Replacement air is drawn into the throat of the ventilator from the
building causing continuous ventilation.
The Hurricane will even
rotate and exhaust in the absence of wind using thermal currents developed
within the building.
The action of wind is an important factor in the development of calibrated
natural ventilation devices and is the third factor or force used in the
calculation of ventilation schemes to provide a given number of air
changes per hour.
The application of
most common fault in the development of natural ventilation systems is the
poor use of louvres. Air cannot be drawn out of a building unless openings
in the perimeter walls allow replacement air to enter. Weatherproof
louvres are designed for this purpose and should be considered for use
whenever access openings such as doors and windows are inadequate or not
Louvres should be located near to floor level so as to introduce fresh air
at ambient temperature into the “Zone of Occupation”. Louvres installed
high in the walls above the zone of occupation will virtually ‘short
circuit’ the ventilation system resulting in no air movement in the zone
A properly designed ventilation system requires exhaust outlets to be at
the highest point possible and inlets for fresh air to be at the lowest
point possible. This ensures that full advantage is taken of natural
convection currents within the building.
It is important to note however, that the installation of louvres will
not, on their own, provide adequate ventilation by the so-called action of
“cross flow”. In reality this horizontal movement of air, or “cross
ventilation”, does not happen.
A cardinal rule of natural ventilation is that you cannot expect airflow
through an opening in which wind can blow. A lower pressure inside the
building is required for fresh air to enter; this being created through a
continuous extraction of air from roof mounted ventilators.
Therefore, it is essential that louvres be used in conjunction with roof
mounted ventilators, such as the Hurricane, to ensure a positive flow of
fresh air and create vertical air movement.
Efficient natural ventilation
Absence of roof ventilators prevents hot and stale air escaping
designed ridge ventilators do not promote adequate ventilation or
air movement in building.
Efficient turbine ventilators exhaust hot and stale air and provide
a given number of air changes per hour for the building.
What can be
The installation of Hurricane™
Turbine Ventilators on a building will ensure that air is exhausted at a
predetermined rate provided that replacement air can enter the building.
The calculations to determine a
ventilation scheme for a particular building take into account the volume
of the building, the height of the ventilator above the inlet areas and
the desirable temperature difference between ambient air and air at the
point of discharge.
The formula used assumes a temperature difference of 10°C between
inlet air at close to floor level and exhaust air at the ventilator. The
incoming air would be at ambient temperature, which is the best that can
be achieved without introducing cooling equipment. This air will rise as
it is warmed by the various heat sources (persons, machinery, solar, etc.)
and will leave the building a maximum of 10°C above ambient temperature.
The zone of occupation from ground level to say 3 meters high would be
maintained at close to ambient temperatures if the inlet areas are
correctly positioned. Obviously, if air is introduced at a high level,
much of the benefit of the ventilators will be lost in the zone of
It is safe to assume that with a
well designed scheme, the zone of occupation of the building will be
maintained at a comfortable temperature.
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