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Specification Value
Marley
/
NC Class Stainless Cooling Tower
/
Specifications: Options
18
shall be operated as a stand- alone sys-
tem without the need for a BMS system.
Operator controls shall be mounted
on the front of the enclosure and shall
consist of start and stop control, bypass/
VFD selector switch, Auto/Manual
selector switch, manual speed control,
and solid-state temperature controller.
An emergency bypass selector switch
internal to the panel allowing the cooling
tower fan motor to be run at full speed
shall be furnished. To prevent heating
problems in the cooling tower fan motor
and to assure proper gear box lubrication
the VFD system shall de energize the
motor once 25% motor speed is reached
and cooling is no longer required. The
VFD shall include de-icing logic with auto
canceling and adjustable time. Speed
in De-Ice mode shall not exceed 50 %
motor speed. The cooling tower manu-
facturer shall supply VFD start-up assis-
tance. Tower vibration testing throughout
the speed range is required to identify
and lockout any natural frequency vibra-
tion levels which may exceed CTI guide-
lines.
Miscellaneous Options
Motor out of the Airstream:
6.1 Add the following to the end of this
paragraph: The motor shall be mount-
ed outside the casing of the tower, and
shall be connected to the gear reducer
by a dynamically-balanced, stainless
steel tube and flange driveshaft.
Fan Cylinder Extensions:
9.1 Insert the following after the first
sentence: Fan cylinder extensions
shall be provided to elevate the fan dis-
charge to a height of ___ m above the
fan deck level.
■ For many years, a feature of
Marley cooling towers was that
the electric motors were located
outside the fan cylinders, where
they were easily accessible, and
where they were not subjected to
the constant humidity that exists
inside the tower plenum.
Although improved motor designs
(insulation, bearings, seals, and
lubricants) have now made it fea-
sible for us to locate the motor inside the tower in close-coupled prox-
imity to the Geareducer
®
(page 7), many users still prefer the motor to
be located outside the humid airstream. If you are among those users—
or are among those who see the wisdom of their thinking—please spec-
ify this option. If you do, however, please require it of all bidders.
■ Extensions are available in 305mm increments to a maximum height
equal to the diameter of the fan. Such extensions may be considered
necessary in order to elevate the discharge beyond the bounds of an
enclosure. Discuss applicability with your local Marley sales representa-
tive.