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Arrangement 1 |
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This is perhaps the most common arrangement for
industrial and other applications. It is available
in SISW and usually belt driven. Two bearings are
mounted on a pedestal and the wheel is overhung to
one side. The bearing pedestals are internal on
axial fans. |
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Arrangement 2 |
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This arrangement is similar to arrangement 1 except
the bearing pedestal is supported by the fan
housing. Two separate bearings may be used although
at one time it was more common to see this
arrangement with the 2 bearings races in a common
bearing housing. A/2 is usually belt driven. |
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Arrangement 3 |
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This arrangement is available in both SISW and DIDW.
A bearing is bracket mounted on each side of the
housing . . . or on axial fans, on each side of the
wheel. This results in a compact unit. Since one or
both of the bearings are in the airstream, A/3 is
usually not used in application where dirt and/or
heat will run through the fan. The bearing bracket
supports can make it difficult to add ductwork to
the inlet or inlets of the fan. A/3 is usually belt
driven. |
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Arrangement 4 |
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In this arrangement, the wheel is directly mounted
on the motor's shaft (& bearings). The fan itself
does not have a shaft or bearings. This arrangement
is more common in axial or smaller centrifugal fans
where proportions allow the motor shaft to reach the
wheel hub. However, some manufactures offer A/4
centrifugals up to 200 HP as standard. Due to the
close coupling of the motor, Arrgt. 4 fans are
normally restricted to a maximum temperature limit
of 200°-F or less and it is common to add some type
of volume control to the fan since variable speed
motors are often not economically available. |
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Arrangement 7 |
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An arrangement 7 fan is an arrangement 3 fan with a
motor base attached to the drive side. It is
designed to be direct driven through a flexible
coupling, with the motor (or turbine) mounted on the
attached base. The same cautions that apply to
arrangement 3 fans apply to arrangement 7. A very
practical use is in large mechanical draft fans
which use inlet boxes. In that case, it eliminates
the need for separate independent bearing pedestals
which can simplify installation. Arrangement 7 is
available in SISW and DIDW. |
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Arrangement 8 |
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This arrangement is similar to an arrangement 1 fan.
A smaller "outrigger" motor or turbine base is
customer provided, or shipped attached to the
bearing pedestal, for direct connection through a
coupling. It is most often used where V-belt drives
are not appropriate, as with very high horsepower's. |
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Arrangement 9 |
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This is an arrangement 1 belt driven fan with the
motor mounted on the fan rather than on the "floor".
It allows factory assembly of the motor and drives.
On higher horsepower fans, the industry sometimes
refers to arrangement "9H". In this modification of
arrangement 9 the motor is mounted on the structural
steel base that is furnished by the fan manufacture.
It also allows factory assembly of the motor and
drives. |
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Arrangement 10 |
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This SISW arrangement is similar to an arrangement 9
fan except the motor is mounted inside of the
bearing pedestal. This offers some degree of weather
protection to the motor however it restricts the
motor size. It is most important to provide adequate
ventailation to the motor in A/10. |
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Air Movement and Control Association (AMCA)
standards include the option of either belt drive or
direct drive for most arrangements. Rare and often
impractical drive options have been omitted. |
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