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Specification Value
Marley
/
Sigma F Series Cooling Tower
/
Specifications: Base
15
4.0 Fan Deck and Fan Cylinder:
4.1 The fan deck shall act as a working
platform for maintenance personnel. It
shall consist of 1 1/8" (28.5 mm) deep
pultruded fiberglass interlocking pan-
els, supported by structural fiberglass
joists on 3'-0" (914 mm) maximum
centers. Fan deck shall have a nonskid
surface. Deck shall be designed for a
uniform live load of 60 psf (2.9 kPa)
or a concentrated load of 400 pounds
(181 kg). Mid-span deflection at 60 psf
(2.9 kPa) loading shall not exceed 0.17"
(4.3 mm).
4.2 Fan cylinders shall be molded FRP.
They shall be anchored to the fan deck
structure to provide a consistently
stable operating shroud for the fan.
5.0 Mechanical Equipment:
5.1 Fan(s) shall be propeller-type, incor-
porating heavy duty blades of high
strength, inert fiberglass reinforced
epoxy material. Blades shall be indi-
vidually adjustable and replaceable.
Fan(s) shall be driven through a right
angle, industrial-duty, oil-lubricated,
geared speed reducer. Speed reducers
employing pulleys and belts will not be
accepted.
5.2 Motor(s) shall be ____ hp maximum,
TEFC, 1.15 service factor, and specially
insulated for cooling tower duty. Speed
and electrical characteristics shall be
1800 (1800/900) RPM, single winding,
___ phase, ___ hertz, ___ volts.
5.3 Motor shall be located outside the fan
cylinder at the fan deck, and shall be
connected to the speed reducer by a
tubular stainless steel, dynamically bal-
anced driveshaft with heavy galvanized
yokes and neoprene flexible coupling
elements.
■ The indicated design values for framing and decking not only
give you assurance that the tower can withstand long term
operation in a hostile environment—but that it will accept many
years of inspection and maintenance traffic by your operating
personnel.
Fiberglass-reinforced polyester fan cylinders provide the close tip
clearances and smooth airflow contour necessary for good fan
performance. The inert, noncorroding nature of FRP assures that
these characteristics will persist.
■ Standard fan drives of other manufacturers may use V-belts.
Considering the size of fans involved—and the horsepower
applied—this is not good design practice. Geareducer drive is
far more reliable and trouble free, and is currently offered as an
option by most other cooling tower manufacturers.
The primary means of capacity control on cooling towers is by
cycling fans on and off, or through a variety of speed changes.
Such cycling can stretch V-belts, and can reduce their service life
significantly.
Unless otherwise specified, motor speed will be 1800 RPM in
60 Hertz areas and 1500 RPM in 50 Hertz areas. If you prefer the
operating flexibility of two-speed operation, please specify the
RPM to be 1800/900 (1500/750 in 50 Hertz regions). Other speed
ranges are also available,
The driveshaft turns at the motor speed and is, therefore, most
sensitive to operational imbalance. Stainless steel manufacture
assures that the driveshaft will not become unbalanced as a
result of corrosion. Stainless steel yokes are available at extra
cost, although not normally necessary.
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