SPX Cooling Technologies SS-NC-08A User Manual
Marley NC Class Stainless Crossflow Cooling Tower
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Product Specifications
Marley / NC Class Stainless Cooling Tower / Contents
Specifications / Base
Base 4
Thermal Performance 4
Performance Warranty 5
Design Loading 5
Construction 6
Mechanical Equipment 7
Fill, Louvers and Drift Eliminators 8
Hot Water Distribution System 9
Casing, Fan Deck and Fan Cylinder 9
Access 10
Cold Water Collection Basin 10
Specifications / Options
Convenience and Safety Options
Guardrail and Ladder 11
Ladder Extension 11
Ladder Safety Cage 11
Ladder Safety Gate 11
Access Door Platform 12
Plenum Walkway 12
Interior Mechanical Equipment Access Platform 12
2
Control Options
Fan Motor Starter Control Panel 14
Vibration Limit Switch 15
Basin Heater 15
Electric Water Level Control 15
Fan Motor Variable Speed Drive 16
Marley Premium VFD System 17
Miscellaneous Options
Motor Outside of the Airstream 18
Fan Cylinder Extensions 18
Inlet Flow Control Valves 19
Equalizer Flume Weir Gate 19
Sound Control 19
Inlet Sound Attenuators 19
Outlet Sound Attenuators 20
Low Noise Fan 20
Ultra Low-Noise Fan 21
Single Hot Water Inlet Connection 21
Air Inlet Screens 21
High Wind/Seismic Designs 21
Multicell Basin Equalizer Outlets 22
Basin Sweeper Piping 22
Extended Geareducer Lube Line Dipstick 22
Marley / NC Class Stainless Cooling Tower
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NC Class Stainless Steel towers are factory
assembled, crossflow cooling towers, designed to
serve air conditioning and refrigeration systems as well
as light to medium industrial process loads on clean
water. They evolve from a factory-assembled concept
of towers pioneered by Marley some 50 years ago, and
incorporate all of the design advancements that our
customers have found valuable. The NC Class has been
designed specifically for sound control and tonnage
density and represents the current state of the art in
this cooling tower category.
This booklet not only relates the language to use in
describing an appropriate NC Class cooling tower—
but also defines why certain items and features are
important enough to specify with the intention of
insisting upon compliance by all bidders. The left-hand
column of pages 4 thru 22 provides appropriate text for
the various specification paragraphs, whereas the right
hand column comments on the meaning of the subject
matter and explains its value.
Pages 4 thru 10 indicate those paragraphs which will
result in the purchase of a basic cooling tower—one
that accomplishes the specified thermal performance,
but which will lack many operation—and maintenanceenhancing accessories and features that are usually
desired by those persons who are responsible for the
continued and continuing operation of the system of
which the tower is part. It will also incorporate those
standard materials which testing and experience has
proven to provide acceptable longevity in normal
operating conditions.
Pages 11 thru 22 provide paragraphs intended to add
those features, components and materials that will
customize the tower to meet the user's requirements.
Space does not permit definition and explanation of all
of the possible options that can be applied to the
NC Class. We realize that you, the purchaser, must
be happy with the tower's characteristics, and we are
prepared to provide—or provide for—any reasonable
enhancement that you are willing to define and
purchase. Your needs will become part of the
continuing evolution of this Marley product line.
Specifications
Specification Value
Marley / NC Class Stainless Cooling Tower / Specifications: Base
4
1.0 Base:
1.1 Provide an induced draft, crossflow
type, factory assembled, film fill,
industrial duty, stainless steel cooling
tower situated as shown on the plans.
The limiting overall dimensions of
the tower shall be _____ wide, _____
long, and _____ high. Total operating
kilowatt of all fans shall not exceed
____ kW, consisting of ___ @ _____
kW motor(s). Tower shall be similar and
equal in all respects to Marley Model
____________.
■ Your specification base establishes the type, configuration, base materi-
al and physical limitations of the cooling tower to be quoted. During the
planning and layout stages of your project, you will have focused your
attention on a cooling tower selection that fits your space allotment,
and whose power usage is acceptable. Limitations on physical size and
total operating horsepower avoid the introduction of unforeseen operational and site-related influences. Specifying the number of cells, and
the maximum fan kW/cell will work to your advantage.
The benefit of crossflow towers is that they are inherently easy to operate, access and maintain. Compared to counterflow towers, crossflow
towers have a spacious plenum between banks of fill for easy access to
all of the tower’s internal components, plus the water distribution system is adjacent to the fan deck and can be maintained during operation.
The NC is also available unassembled for on-site assembly.
Specifications
Specification Value
Marley / NC Class Stainless Cooling Tower / Specifications: Base
5
2.0 Thermal Performance and Efficiency:
2.1 The tower shall be capable of cooling
_____ m
_____ °C at a design entering air wetbulb temperature of _____ C and its
thermal rating shall be Certified by the
Cooling Technology Institute.
2.2 The tower shall be capable of a mini-
mum _____ m
ASHRAE Standard 90.1.
2.3 CTI Certification notwithstanding,
the cooling tower manufacturer shall
guarantee that the tower supplied
will meet the specified performance
conditions when the tower is installed
according to plan. If, because of a
suspected thermal performance deficiency, the owner chooses to conduct
an on-site thermal performance test
under the supervision of a qualified,
disinterested third party in accordance
with CTI or ASME standards during the
first year of operation; and if the tower
fails to perform within the limits of
test tolerance; then the cooling tower
manufacturer will pay for the cost of
the test and will make such corrections
as are appropriate and agreeable to the
owner to compensate for the performance deficiency.
3
/h of water from ____ °C to
3
/h/kilowatt efficiency per
■ CTI Certification means that the tower
has been tested under operating conditions and found to perform as rated by
the manufacturer under those circumstances. It assures the buyer that the
tower is not intentionally or inadvertently undersized by the manufacturer.
■ The minimum efficiency per ASHRAE
Standard 90.1 for induced draft open cooling towers applied to comfort
cooling is 8.68 kW @ 35/29.5/24. There are no efficiency requirements for
non-comfort cooling applications. If you want greater efficiency you can
require it by specifying a higher ASHRAE Standard 90.1 m
■ CTI certification alone is not sufficient to assure you that the tower
will perform satisfactorily in your situation. Certification is established
under relatively controlled conditions, and towers seldom operate
under such ideal circumstances. They are affected by nearby structures,
machinery, enclosures, effluent from other towers, etc. Responsible and
knowledgeable bidders will take such site-specific effects into consideration in selecting the tower—but the specifier must insist by the written
specification that the designer/manufacturer guarantee this “real world”
performance. Any reluctance on the part of the bidder should cause you
some concern.
3
/h/kilowatt.
3.0 Warranty:
3.1 The entire tower, including structure, casing, basins, decking, fan(s),
motor(s), and all mechanical drive components (including belts, if used) shall
be warranted against failure due to
defects in materials and workmanship
for a period of five (5) years from the
date of shipment to the job. Towers not
covered by a warranty of this scope
will not be accepted.
4.0 Design Loading:
4.1 The tower structure, anchorage and all
its components shall be designed by
licensed structural engineers per the
International Building Code to withstand a wind load of 1.44k/Pa, as well
as a .3g seismic load. The fan deck
and hot water basin covers shall be
■ It is important to understand the distinction between structure and
anchorage. Specifying that only the anchorage meet these require-
ments means the tower can become non-functional, even fall down, yet
remain attached to the foundation. Specifying structure will require the
tower to remain operational.
The indicated design values are the minimum allowables under accepted design standards. They give you assurance that the tower can be
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Specifications
Specification Value
Marley / NC Class Stainless Cooling Tower / Specifications: Base
6
designed for 2.4kPa live load or a 91kg
concentrated load. Guardrails, where
specified, shall be capable of withstanding a 890N concentrated live load
in any direction, and shall be designed
in accordance with OSHA guidelines.
5.0 Construction:
5.1 Except where otherwise specified, all
components of the cooling tower shall
be fabricated of heavy-gauge, series
300 stainless steel. The tower shall be
capable of withstanding water having a
chloride content (NaCl) up to 750 mg/L;
a sulfate content (SO4) up to 1200
mg/L; a calcium content (CaCO3) up to
800 ppm; silica (SiO2) up to 150 mg/L;
and design hot water temperatures
up to 52°C. The circulating water shall
contain no oil, grease, fatty acids, or
organic solvents.
5.2 The specifications, as written, are
intended to indicate those materials
that will be capable of withstanding
the above water quality in continuing
service, as well as the loads described
in paragraph 4.1. They are to be regarded as minimum requirements. Where
component materials peculiar to individual tower designs are not specified,
the manufacturers shall take the above
water quality and load carrying capabilities into account in the selection of
their materials of manufacture.
shipped, handled, hoisted—and ultimately operated in a normal cooling
tower environment. Most NC Class models will withstand significantly
higher wind and seismic loads. If your geographic location dictates
higher wind load or seismic load values, please make the appropriate
changes, after discussion with your Marley sales representative.
Note: Some countries and states (Florida) require structure not anchor-
age. Check with you local officials.
1.44k/Pa windload, .3g seismic load—applicable for most applications
but consult the local code official for actual requirements.
2.4kPa live load, 890N concentrated load—ensures the tower can be
safely accessed for routine maintenance when a guardrail is installed as
well ensuring the end user complies with government safety laws.
■ For pure resistance to corrosion—coupled with the capability to meet
stringent fire and building codes—there is no substitute for stainless
steel! No paints or electrostatically-applied coatings, however exotic
they may be, can match stainless steel's ability to withstand adverse
operating conditions.
Although SPX Cooling Technologies makes use of many structural FRP
components in various other product lines, they are held to a relative
minimum in the NC Class Stainless line. This is to assure that there will
be no question as to the structural integrity, fire resistance, and life
expectancy in the mind of the owner.
Except for those unusual operating situations where the circulating
water may be so laden with suspended solids, algae, fatty acids, product fibers, active organisms reflected in BOD, and the like that plugging of film type fill is a probability, the NC Class Stainless is relatively
immune to poor water quality. Where such conditions do exist, however, thought should be given to the prevention of such carryover—or
to the use of a Marley splash-fill product. Please discuss your situation
with your Marley sales representative.
Factory Assembly
Specifications
Specification Value
Marley / NC Class Stainless Cooling Tower / Specifications: Base
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5.3* The tower shall include all design and
material modifications necessary to
meet the fire rating requirements of
Factory Mutual. The product proposed
shall be listed in the FM Approval
Guide, latest edition.
*Standard on models NC8301 thru NC8309. Available
as an option on models NC8310 thru NC8312.
6.0 Mechanical Equipment:
6.1 Fan(s) shall be propeller-type, incor-
porating wide-chord aluminum alloy
blades and galvanized hubs. Blades
shall be individually adjustable.
Maximum fan tip speed shall be 66
m/s. Fan(s) shall be driven through a
right angle, industrial duty, oil lubricated, geared speed reducer that requires
no oil changes for the first five (5)
years of operation. The gearbox bearings shall be rated at an L
service
10A
life of 100,000 hours or greater.
6.1 (alternate)* Fan(s) shall be propeller-
type, incorporating wide-chord aluminum alloy blades and galvanized hubs.
Blades shall be individually adjustable.
Fan(s) shall be driven through a onepiece multi-groove, solid back V-type
belt, pulleys, and tapered roller bearings. Bearings shall be rated at an L
10A
service life of 40,000 hours or greater.
*Currently available on Models NC8304 through
NC8309.
6.2 Motor(s) shall be ____ kW maximum,
TEFC, 1.15 service factor, variable
torque, and specially insulated for cooling tower duty. Speed and electrical
characteristics shall be ______ RPM,
single-winding, ___ phase, ____ hertz,
____ volts. Motor shall operate in the
shaft-horizontal position, and nameplate kilowatt shall not be exceeded at
design operation.
■ The Marley NC is the only crossflow
cooling tower approved for single-cell
FM installations. This could have a very
beneficial effect upon your fire insurance
premiums. Towers not able to meet FM
requirements may require the inclusion
of a fire protection sprinkler system to
achieve a comparable level of insurance premium cost. Even if you are not
insured by FM, this requirement ensures that each cell will contain any
fire that may occur without losing the ability of limited operations and
capacity.
■ Propeller-type fans require only half the operating hp of blower-type
fans. However, they should be readily adjustable to permit compensation for jobsite conditions.
With NC, the choice is yours. The exclusive Marley System5
Geareducer
®
requires no oil changes for five years, offering you
unmatched reliability and low maintenance. Ideal for owners concerned
about downtime or maintenance costs. Currently available on 49 NC
models, the Marley Power Belt drive system features all-aluminum
sheaves, power band belts and long-life bearings for dependable service.
TEFC motors offer additional benefits over TEAO motors whose only
source of cooling is the flow of air produced by the cooling tower fan.
This air rate is not always ideal due to motor position, blockage, etc.
TEFC ensures the motor will always be cooled properly.
Unless otherwise specified, motor speed will be 1500 RPM on standard
models. Low noise models will use motor speeds appropriate for the
specific model. If you prefer the operating flexibility of two-speed operation, please specify two-speed, single-winding motors which offer full
and half speeds for maximum energy savings. Incidentally, two speed
motors are a better choice than separate “pony” motors which simply
double the problems indicated above and induce parasitic loads during
operation for lower than nameplate efficiency.
6.3 The complete mechanical equipment
assembly for each cell shall be supported by a rigid steel structural support
that resists misalignment between the
motor and the gear reducer.
Specifications
Specification Value
Marley / NC Class Stainless Cooling Tower / Specifications: Base
8
7.0 Fill, Louvers and Drift Eliminators:
7.1 Fill shall be film type, thermoformed
of 0.40mm thick PVC, with louvers
formed as part of each fill sheet. Fill
shall be suspended from hot dip galvanized structural tubing supported
from the tower structure, and shall be
elevated above the floor of the cold
water basin to facilitate cleaning. Air
inlet faces of the tower shall be free of
water splash-out. Fill shall be capable
of withstanding a hot water temperature of 52°C.
7.2 Drift eliminators shall be PVC, triple-
pass, and shall limit drift losses to
0.005% or less of the design water
flow rate.
■ Louvers integral with the fill keep the flowing water within the confines
of the fill. The separate external louvers used by others permit water to
escape the fill and form ice or produce an unsightly situation adjacent
to the tower and waste water. If you
plan to use your tower in the wintertime, particularly for free cooling,
integral louvers will put your operating concerns to rest. Integral louvers
offer the best available technology for
winter operation and water conservation.
Fill options are available for hot water
temperatures up to 60°C.
■ Drift rate varies with design water
loading and air rate, as well as drift
eliminator depth and number of
directional changes. A drift rate of
0.001% is readily available in standard
configuration without premium cost. If a
lower rate is required, please discuss with your
Marley sales representative.
Keep in mind…
• Drift for towers with three-pass high efficiency eliminators constitute a
small percentage of water usage.
• Unlike thermal performance, drift rates are not certified and field drift
tests are cost prohibitive for most applications.
• Drift rates below 0.001 are difficult to measure in the field.
• Certain water treatment chemicals can impact the drift rate.
LOUVERS
DRIFT ELIMINATOR
separate from fill
on some models
FILL
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