the tower plus accessways through any and all partition walls permit access to ....
Partitions in Marley steel collection basins include bolt-on steel weir plates to ...
/ Marley Sigma Steel Cooling Tower /
/ The Marley Difference /
You’ll enjoy single source responsibility and reliability
How many other cooling tower companies can offer
because SPX Cooling Technologies designs and
you this assurance? They may use Brand “A” nozzles with
manufactures virtually all major cooling tower components.
Brand “B” fill and Brand “C” drift eliminators. When they all
All Marley components are designed and selected to be
come together, the whole may be less than the sum of the parts.
part of an integrated system. For example, the spray pattern from nozzles and the pressure drop through drift eliminators
Our total system approach assures that all the
both affect a fill’s heat transfer capacity. So, we include that
parts work together to provide you the greatest total
impact in our thermal analysis.
performance.
Drift eliminators must be effective at the air velocities
And because we design specifically for cooling towers,
where fill is most efficient. So, we’ve carefully designed both
all our components will provide many years of service with
components to work together efficiently.
minimal maintenance.
Approval Available
2
/ Sigma Tower Advantages /
■ Guaranteed Performance. Don’t rely on outside
■ Low Operating Costs. Marley high-efficiency fill and fans,
agencies with limited enforcement powers. We’ll stand
gravity-flow water distribution, and efficient Geareducer®
by our responsibility for reliable thermal performance. We
drive work together to offer maximum cooling with
designed it. We rate it. We guarantee it.
minimum power use.
■ Exclusive 5-Year Mechanical Equipment Warranty.
■ Low Maintenance Costs. Induced-draft propeller fans
Your no-cost assurance of trouble-free mechanical
on Marley rightangle Geareducer units, TEFC 1.0 or
operation for 5 years. Isn’t that where a lot of your tower
1.15 service factor motors and heavy-duty mechanical
maintenance dollars have gone in the past?
equipment support assure long service life with minimal maintenance.
■ Long Service Life. We’ve carefully chosen all the
■ All-Season Reliability. Sigma Steel towers perform as
materials used in Sigma Steel towers for their corrosion resistance and suitability for cooling tower service. Heavy
specified in the heat of summer. They respond well to
gage steel hot dip galvanized after fabrication, stainless
energy management techniques in spring and fall. They
steel, PVC and fiberglass keep your Sigma Steel tower
operate virtually ice-free in the dead of winter. And they
working year after year.
offer simple maintenance all year long. We guarantee it. ■ Single Source Parts Availability. SPX designs,
■ Efficient Field Assembly. Precise factory fabrication assures that every component in your Sigma Steel tower
manufactures, guarantees, and stocks all major
will fit as designed. SPX Cooling Technologies offers an
components of the tower except motors. We’ll have the
unparalleled nationwide construction organization to build
parts if you ever need them.
your tower quickly and economically. 3
/ Construction and Components / ■ Fill, Louvers, and Drift Eliminators
■ Mechanical Equipment
Marley high-performance film fill is the heart of every
You’ll receive a 5-year warranty against failure of any
Sigma Steel tower. A repeating chevron pattern provides the
mechanical component in the fan drive system (except the
wetted surface and air turbulence necessary for proper heat
motor, which is warranted by its manufacturer).
transfer while minimizing resistance to airflow so you’ll save on fan power. Molded protrusions on each fill sheet assure uniform spacing. Fill sheets are thermoformed from 15 mil (.015″) thick PVC (polyvinyl chloride) stock capable of service at hot water temperatures up to 125°F. Four stainless steel structural tubes resting in stainless steel hangers support the fill while PVC tubes control alignment at mid-height and at the bottom of the fill. This system also holds the bottom of the fill sheets above the cold water basin floor to simplify basin cleaning.
The Marley Geareducer speed reducer used in the Sigma line contributes a long record of dependability, long service life, and low maintenance to this assurance of reliability. Their designs meet or exceed the requirements of CTI STD-111 and AGMA Std. 420.04. Every Geareducer unit is run-in under load prior to shipment to make sure that it will operate properly on your tower.
Fill sheets include both louvers and drift eliminators. The louvers in this patented arrangement keep water on the fill sheets and in your tower, and also assure proper heat transfer throughout wide variations in airflow. Users find this fill operates ice-free even in extremely cold weather. Integral drift eliminators prevent the costly nuisance of drift spotting on objects in the surrounding environment. Their unique shape induces the air flow through three distinct direction changes as illustrated at right. The final turn directs air toward the fan to save you fan horsepower. Moisture carried in the air stream can’t make these abrupt turns, so drift is 0.010% or less of the circulating water flow rate. 4
Housings are gray cast iron. Gears are high-strength,
Fans operate inside structural FRP (fiber reinforced
case hardened alloy steel. And all bearings are tapered roller
polyester) eased-inlet fan cylinders designed and applied
bearings. A variety of available horsepower capacities and
to maximize fan performance. Standard cylinders are either
reduction ratios lets us choose the optimum Geareducer
6′-0″ or 7′-0″ tall, depending on fan diameter, so all Sigma
model and fan speed for your job. Service factors are always
Steel towers comply with OSHA standards without need of
2.0 or greater as applied.
fan guards.
Splash-type lubrication and integral cooling fins preclude the need for maintenance-intensive oil pumps and coolers. A constant oil bath or flow lubricates every bearing in forward or reverse motion—at full or half speed. All Marley Geareducer assemblies are right-angle type with motors located outside the tower’s saturated airstream. A galvanized steel lube line runs from the Geareducer unit to a standpipe near the motor on each cell, so you can check oil level and change or add oil while standing on the fan deck.
Marley driveshafts transmit power from the motor to the Geareducer assembly. Standard Marley driveshafts include 304 stainless steel tubes with welded-on stainless steel flanges and bonded neoprene flexible elements to transmit torque. Marley driveshafts are full-floating assemblies with non-lubricated flexible couplings on each end. Their tolerance to misalignment and torsional shock is unequalled in nonspecialized units. All Marley driveshafts are dynamically balanced at the factory to minimize operating vibrations. All Sigma Steel towers offer the benefits of adjustable
Welded unitized hot dip galvanized steel supports
pitch propeller type Marley fans. The H-3 Series fans normally
maintain alignment throughout the mechanical equipment
used on smaller models incorporate cast aluminum blades
system. Marley torque-tubes provide superior strength and
and machined aluminum hubs. HP-7i Series fans, used on
stability. Their cylindrical shape also keeps operating costs
larger models, include hollow GRE (glass-reinforced epoxy)
down by minimizing airflow restrictions and by reducing air
blades and epoxy-coated cast iron hubs. Blades on both fan
turbulence in the fan entrance region.
types are adjustable in pitch, so you can take full advantage of rated horsepower or adjust the pitch to compensate for
■ Water Distribution System
unusual jobsite restrictions. The true airfoil blades, designed
The gravity-flow water distribution system designed into the
specifically for cooling towers, offer efficient, quiet operation
Sigma tower essentially reduces pump head to its most basic
and long service life.
component—static lift—saving you money on pump power. You won’t have to force water through internal piping and pressure spray nozzles, as you would in a counterflow tower.
5
■ Structure and Materials
Warm water enters the system through the Sigma galvanized crossover pipe. Inlet connections for your piping
Sigma Steel tower design conforms to the latest edition
conform to standard 125# flanges. Marley flow-control
of the design standards of ASCE (American Society of
valves balance the flow to both distribution basins of each
Civil Engineers). Wind load criterion is normally 30 pounds
cell. Water flows from the valves into covered FRP stilling
per square foot of projected area and the design meets
chambers, through a longitudinal FRP flume and then into
5%g seismic loading. Materials selections are based on a
the hot dip galvanized steel distribution basin.
maximum water temperature of 125°F. The Sigma Steel structure is a system of mill shape angles, cold-formed channels, and cold-formed angles. All structural members are hot dip galvanized after fabrication in accordance with ASTM A123. Average zinc thickness on structural members varies from 2.55 mils to 3.9 mils, depending on the steel plate thickness as defined in ASTM A123. Galvanizing after fabrication assures you that the steel in your tower is entirely protected from the effects of corrosion, even on the ends and through bolt holes. You’ll enjoy long, reliable corrosion resistance in most operating environments. For even greater protection, you can choose from several stainless steel options, described on page 11.
Polypropylene “Spiral Target” nozzles in the basin floor then distribute the water uniformly over the fill. All materials in the water distribution system offer long life and minimal maintenance. Valves consist of cast iron bodies and grease-lubricated stainless steel operating stems. Basins are hot dip galvanized after fabrication in accordance with ASTM A123, which requires average zinc thickness of 2.55 mils. Polypropylene nozzles and FRP flumes are chemically and biologically inert.
Columns in all Sigma Steel towers are cold-formed channels located on 4′-0″ longitudinal centers. All columns are anchored to the basin. Transverse channel diagonals carry lateral loads to heavy-duty hot dip galvanized steel anchor plates. Mill shape angles provide longitudinal bracing. 6
■ Casing
All structural framing connections use 1/2″ or 5/8″ diameter hot dip galvanized machine bolts.
Tower endwalls are cased with gray 8 oz/sq ft corrugated
The fan deck is hot dip galvanized steel designed for a
FRP sheets. Water and corrosion-proof, FRP is immune to
uniform live load of 60 psf.
biological deterioration and requires no maintenance.
■ Access and Safety
sheets are overlapped one corrugation and are sealed.
Corrugations run vertically. All vertical joints between Casing attaches to the structural members with stainless
The Sigma Steel tower is designed to meet all OSHA requirements. A 3′-6″ high galvanized guardrail system
steel fasteners and neoprene bonded washers. Corner trim
complete with top rails, intermediate rails and toeboards,
pieces are 12 oz/sq ft molded FRP.
surrounds the entire top perimeter of the tower.
■ Cold Water Basin Most Sigma Steel owners install their towers over concrete cold water basins provided by others. However, you can choose a Marley steel collection basin with side outlet sump as an option. See page 10. Consult your Marley sales representative for detailed dimensional drawings and load schedules to help you with your basin design.
Aluminum ladders attached to the tower endwalls provide access to the fan deck level. Ladders begin at the cold water basin level and end at the top of the guardrail system. Each tower normally includes two ladders (one at each endwall). Hinged doors through the endwall casing at each end of the tower plus accessways through any and all partition walls permit access to the interior of the tower at the basin level. All mechanical equipment is accessible both from the interior of the tower and through the fan cylinder. Every component of every tower is removable and replaceable.
7
/ Available Options /
Accessory
Description and Remarks
Accessory
HDG Steel Cold Water Basin
Hot dip galvanized steel collection basin with side-outlet sump for towers located above grade. See page 10.
FM (Factory Mutual) Approval
Simple modifications allow Sigma Steel towers to meet Factory Mutual requirements for fire resistant construction.
Stainless Steel Cold Water Basin
For corrosive environments or where dictated by experience or personal preference. See pages 10 and 11.
Steel Stairway
Bottom Outlet Sump
Square-plan galvanized steel sump with bottom outlet. Outlet connection hole and bolt circle conform to 125# ASME pipe connection. Includes a plugged drain connection in sump bottom.
Hot dip galvanized steel 45° stairway located at tower endwall provides access to the fan deck. Choose a stairway in place of one endwall ladder, or use both ladders as well as the stairway. Handrails and kneerails are standard, so design conforms to OSHA standards.
Steel Ladder
Collection Basin Clean-Out Box
Square-plan galvanized steel box with 3″ or 4″ diameter bottom outlet flange connection facilitates basin cleaning.
Galvanized steel ladder conforms to OSHA standards. May be in place of or in addition to standard aluminum ladders.
Ladder Safety Cage
Steel Casing
G-235 mill-galvanized steel sheets are installed with interlocking flanges at all horizontal joints.
Stainless Steel Construction
Choose from several options, providing different degrees of protection against corrosion. See page 11.
Galvanized steel circular framework bolts to ladder siderails and conforms to OSHA standards. Cages extend from the top of the guardrail to about 7′-0″ above the base of the ladder. If the tower fan deck is more than 20′-0″ above roof or grade, OSHA requires safety cages.
Plenum Walkway
Hot dip galvanized steel plenum walkways extend the full length of the tower from access door to access door above the water line. Guardrails are optional. However, OSHA requires guardrails if the walkway is 4′-0″ or more above the basin floor.
Ladder
Used when tower is elevated appreciably above access level. Extensions attach to the normal ladder and may require base anchorage (depending on length).
Cell Partitions
Basin partitions between fan cells for specific operating considerations. See page 9.
Steel Hot Water Basin Covers
Removable, G-235 galvanized steel covers keep upper basins free of leaves and debris. They also tend to retard growth of algae by keeping ultraviolet radiation away from the warm water in the basins. Covers may be used as a walking surface for tower maintenance.
Air Inlet Screens
Vibration Limit Switches
Extensions
Galvanized wire mesh screens over the air inlets keep leaves and trash out of the tower. Easily removable. Includes galvanized steel U-edge frames. Stainless steel screens and frames are also available.
Non-Skid Fan Deck Covering
Non-slip strips overlayed on walking areas provide extra security for operating and maintenance personnel.
Fan Cylinder Extensions
Optional flared fan cylinder extensions improve fan efficiency to reduce your operating costs. Extensions increase cylinder height to 10′-0″. Not available for 120″ fan diameters.
Geareducer Oil Level Gauge
A brass-fitted oil level sight glass takes the place of the dip stick on the external oil fill and drain system. Permits easy reading of oil level and also lets you change oil through the lube line.
Robertshaw or Metrix single-pole, double-throw vibration switches in NEMA 4 housing. Doublepole, double-throw models are also available.
8
Description and Remarks
/ Available Options /
Ladder with Safety Cage
■ Cell Partition Options Every Sigma Steel tower includes plenum chamber partitions, fill area partitions and hot water distribution
Oil-Level Sight Glass
basin partitions between adjacent cells. Plenum partitions ensure consistent thermal performance as you shut off one
Complete watertight partitions provide total cell isolation.
fan at a time. They keep air from entering an operating cell
These partitions let you use adjacent cells to serve separate
through an adjacent idle fan, an effect that reduces thermal
loads with incompatible system temperatures. Watertight
performance. Collection basin partitions let you inspect and
partitions extend from louver-face to louver-face and cover
clean individual basins while the rest of the tower continues
the full internal height of the tower, including the cold water
to operate.
basin. Partitions usually consist of G–235 galvanized steel, sealed to cold water basin partitions made from the same material as the basin sides. For concrete basin partitions, Marley drawings specify the appropriate design dimensions. Partitions in Marley steel collection basins include bolt-on steel weir plates to let you mix or segregate the water in the basin to meet your operating needs.
Steel Casing
9
/ Special Component Options / ■ Cold Water Collection Basins If you plan to locate your tower above grade, a Marley steel cold water collection basin, in either galvanized or stainless steel construction, complete with the necessary operating accessories is available as an option. Galvanized basins are hot dip galvanized after fabrication and assembled using field bolted and sealed joints between adjacent sheets. Stainless steel basins may be either field bolted or field welded, depending on your preference, but can only be specified with an all stainless steel Sigma tower to eliminate the potential for galvanic corrosion between galvanized and stainless steel. Every standard basin includes at least one depressed, side-outlet sump. The number and size of sumps depend
Depressed side-outlet sump
on the circulating water rate and the overall size of the tower. Unless otherwise specified, sumps include a drain and a stainless steel or hot dip galvanized debris screen. You may
■ High Design Loadings
choose either galvanized or stainless steel construction.
Our engineers will make sure that your Sigma Steel tower
Each basin includes at least one overflow/cleanout connection consisting of a full coupling and standpipe. The normally-installed standpipe ensures adequate freeboard in the cold water basin and removes easily for flush-out basin cleaning.
will withstand any higher-than-normal design loadings (wind, seismic, decking, etc.) that you may specify. Clearly define any special design requirements in your tower specifications. We’ll make any necessary changes to the tower’s structural design. This is equally true if you anticipate incoming hot
A float-operated, mechanical make-up valve provided with each basin automatically replenishes water lost from the system. The valve is located in the plenum chamber between fill banks, just inside the endwall access door to facilitate
water temperatures above 125°F. The specification should also describe the type of load system served by the tower and include the expected water quality analysis so that our engineers can select and
adjustment and maintenance.
recommend appropriate changes in component materials to assure satisfactory service. Discuss any questions about
■ Non-Standard Motors
technical requirements with your trained Marley sales representative.
Although you can buy your Sigma Steel tower “less motor” at a cost reduction, it is not normally recommended. Motors supplied on Marley towers meet rigorous specifications developed from environmental chamber tests at our Development Center. These specifications represent prudent minimum design requirements. Unless otherwise specified, motors provided on Marley cooling towers are TEFC, 1.0 or 1.15 service factor (appropriate to the applied load), 1800 RPM. Other enclosures (such as Explosion Proof) and motors specially wound for non-standard voltages are available at extra cost. Two-speed motors and motors for variable speed drive applications are also available. Their advantages are discussed in the Sigma Steel Technical Reference Manual.
10
/ Corrosion Protection / ■ Hot Dip Galvanized After Fabrication
■ More effective edge protection. Galvanizing after fabrication assures that all sheared and cut edges receive
Sigma Steel towers meet the rigorous demands of the
the full zinc thickness. Mill-galvanized material relies on
industrial user and the user with large HVAC loads. Cooling
the zinc adjacent to the sheared or cut edge to protect
towers on these types of applications are usually very critical,
the exposed steel in those areas. Your Sigma Steel tower
so the standard materials of construction on all Sigma Steel
will have full protection at all bends, shears, bolt holes—
towers offer excellent corrosion resistance.
throughout the entire tower.
A primary example is the use of steel that has been hot
■ Available on heavier-gauge materials. The steel
dip galvanized after fabrication for all structural members,
thicknesses used for structural members on the Sigma
all steel components (except those that are stainless steel)
Steel tower are typically heavier than those available with
in the wetted section of the tower and all mechanical
mill-galvanizing. The critical nature of most Sigma Steel
equipment supports.
tower installations demands structural design appropriate
Hot dip galvanizing after fabrication offers several
for industrial applications. Hot dip galvanizing after
advantages over mill-galvanizing used by suppliers of similar-
fabrication provides corrosion protection for these heavier
capacity units:
sections.
■ Thicker zinc application. Average zinc thickness on steel
The advantages of hot dip galvanized protection
hot dipped after fabrication is 2.55 mils on all steel up
after fabrication assure you that your Sigma Steel will
to and including 1/16″ thick and 3.91 mils on steel from
provide years of reliable service even on critical industrial
1/16″ to 1/8″ thick. By contrast, the G-210 mill-galvanized
applications. If you want even greater protection, select from
steel offered by other suppliers is only 1.9 mils thick.
the options below.
Sigma Steel towers offer from 34% to 106% additional protection based on zinc thickness alone.
/ Optional Materials / ■ Premium Materials ■ Stainless steel driveshafts. Standard 300 series
All materials used in Sigma Steel towers offer long service life in the corrosive cooling tower environment. PVC fill, FRP
stainless steel tube and flange with cast 316 stainless
and other plastic components are inherently noncorrosive.
steel connecting yokes.
Steel components are either stainless steel or heavygalvanized, depending on their location and service in the
Remember that critical steel components such as fill
tower.
supports and fan assembly hardware are stainless steel on
If your application involves an unusually corrosive
every Sigma Steel tower as standard. If you have questions
environment or chemically aggressive water, or if you prefer
or concerns about material upgrades, contact your Marley
the ultimate in corrosion resistance, you can choose from
sales representative. Give us an analysis of your anticipated
several options:
water quality and we’ll offer material recommendations for
■ Stainless hardware. 300 series stainless steel structural
maximum service life at minimal cost.
hardware (bolts, nuts and washers). The rest of the tower remains heavy galvanized steel. ■ All 300 series stainless steel tower. Every steel component on the tower is stainless steel with the exception of the mechanical equipment. This includes the optional collection basin, if specified.
11
/ Additional Services / SPX Cooling Technologies is dedicated to satisfying the needs of our customers—needs which begin far in advance of the actual purchase of a new Marley cooling tower, and vary over the operating lifetime of the project. Here is a partial listing of the additional services offered by SPX Cooling Technologies to help you do your job most effectively:
Application/Sizing/Layout Services—Sales Engineers are
of repairs above and beyond those categorized as normal
trained to help you choose the proper type and size of cool-
maintenance. Our reconstruction service can return your
ing tower, and will guide you in its appropriate location on
tower to as new condition
site. They will also help you write the specifications for its
Performance Improvement Service—Systems served by
purchase. As the only manufacturer who makes all types of
cooling towers grow in response to demand for the product
cooling products, SPX Cooling Technologies can offer you a
produced by that system. Most customers find that they
wide range of options to meet your requirements.
could produce more product if the cooling tower could deliver
Construction Service—We can supply supervision only—or a complete, experienced crew to handle construction. Parts Service—We maintain a stock of spare parts specific to your Marley tower.
colder water. Fortunately, cooling tower technology advances with time, and we can apply this increased technology to upgrade your tower’s thermal performance. Tower Replacement Service—Occasionally, customers will
Maintenance Service—In addition to providing complete in-
benefit from replacing an installed tower, rather than refur-
structions and continuing guidance, we will provide as much
bishing it. SPX Cooling Technologies stands ready to assist
“hands on” maintenance as you require, or will recommend
you in that endeavor—and, in most cases, the replacement
a local service contractor for your consideration.
will require little or no change to your concrete basin or
Condition Inspection Service—From time to time, for your
support structure.
peace of mind, our engineers can give your tower a thorough inspection to evaluate its current condition. This usually allows you to foresee and forestall problems before they become serious. Reconstruction Service—Due to operating or atmospheric conditions, or age, sooner or later your tower will be in need
7401 WEST 129 STREET OVERLAND PARK, KANSAS 66213 UNITED STATES 913 664 7400
[email protected] spxcooling.com In the interest of technological progress, all products are subject to design and/or material change without notice. ©2008 SPX Cooling Technologies, Inc. Printed in USA | STL-SIG-05
/ Marley Sigma Steel Cooling Tower / Engineering Data & Specifications
Marley / Sigma Steel Cooling Tower / Table of Contents
Engineering Data Schematic 6 Support 7 8 Concrete Basin Piping 9 Environmental 10 11 Energy Management Specifications / Base Base 12 Thermal Performance 13 Construction 14 Fan Deck and Fan Cylinder 15 15 Mechanical Equipment Fill, Louvers and Drift Eliminators 17 Hot Water Distribution System 18 Casing 18 Access 18 Cold Water Collection Basin 19 19 Scope of Work Specifications / Options Control Options Control System Basin Heater Fan Motor Variable Speed Drive Marley Premium VFD System Vibration Limit Switch
20 21 21 22 23
Convenience and Safety Options Stairway 24 Plenum Walkway 24 Ladder Extension 24 Ladder Safety Cage 24 Oil Level Sight Glass 25 Miscellaneous Options Steel Cold Water Basin Factory Mutual Approval Hot Water Basin Covers Air Inlet Screens Low Noise Tower Service Life-Relate Customization
25 25 25 25 26 27
Marley / Sigma Steel Cooling Tower /
T
he Sigma Steel is a galvanized steel, field-erected, general purpose crossflow cooling tower, designed to serve normal air conditioning and refrigeration systems as well as medium sized industrial loads. Evolving from the crossflow concept of towers pioneered by Marley in 1938, and incorporating over 70 years of design advancements, the Sigma Steel 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 Sigma Steel 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 11 thru 25 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 12 thru 19 indicate those paragraphs which will result in the purchase of a cooling tower which will not
5
only accomplish the specified thermal performance— but which will include normal operation- and maintenance-enhancing accessories and features. It will also incorporate those standard materials which testing and experience has proven to provide best results in normal operating conditions. Pages 20 thru 27 provide some 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 Sigma Steel. SPX Cooling Technologies realizes 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 betterment of this Marley product line.
Marley / Sigma Steel Cooling Tower / Engineering Data : Schematic
W OUT-TO-OUT OF TOWER
6
41/2"
CL COLUMN
C DIAMETER FAN
CL COLUMN
A BAYS AT 4'-0" = L
COLUMNCL
41/2"
TOP OF FAN CYLINDER
H
The UPDATE web-based selection software —available at spxcooling.com—provides Sigma Steel model recommendations based on customer's specific design requirements.
Tower Model
GPM per cell
FAN DECK
B
Use this data for preliminary layouts only. Obtain current drawing from your Marley sales representative.
13'-11/8" BASE OF TOWER COLUMNS
Dimensions W
L
H
A
B
C
Maximum Motor hp
Average Pumping Head
121-111
500-4500
25'-4"
12'-0"
19'-1 ⁄8"
3
6'-0"
120"
60
17.3'
122-111
650-6000
27'-4"
16'-0"
19'-11⁄8"
4
6'-0"
144"
60
17.4'
1
123-111
650-6000
29'-4"
16'-0"
20'-1 ⁄8"
4
7'-0"
168"
75
17.4'
124-111
1000-7500
29'-4"
20'-0"
20'-11⁄8"
5
7'-0"
168"
75
17.4'
125-111
1000-7500
33'-4"
20'-0"
20'-1 ⁄8"
5
7'-0"
216"
75
17.5'
126-111
1000-9000
33'-4"
24'-0"
20'-11⁄8"
6
7'-0"
216"
100
17.5'
127-111
1500-10500
33'-4"
28'-0"
20'-1 ⁄8"
7
7'-0"
216"
100
17.6'
1
1
1
NOTE 1 U se this bulletin for preliminary layouts only. Obtain current drawings from your Marley sales representative. 2 Last number of model indicates number of cells. Change as appropriate for your selection. Primary engineering data is per cell.
3 Height shown is from base of tower columns to top of fan cylinder. 4 Pumping head shown is from base of tower columns.
Marley / Sigma Steel Cooling Tower / Engineering Data : Support
7
A SPACES AT 4'-0" = L
6"
AIR INLET FACE
CASED ENDWALL FACE
OVERFLOW
RECOMMENDED OPERATING WATER LEVEL 1'-6"
W
OVERALL OF BASIN
SUMP
CASED ENDWALL FACE
6"
Section
AIR INLET FACE
INTERMEDIATE BEAM
PRIMARY SUPPORT BEAM
Plan Tower Model
Operating Weight lb
Dimensions A
W
L
Single Fan Cell
Each Cell Add
121-111
3
23'-8"
12'-0"
37670
33150
122-111
4
25'-8"
16'-0"
49875
45105
123-111
4
27'-8"
16'-0"
50320
45230
124-111
5
27'-8"
20'-0"
60290
55200
125-111
5
31'-8"
20'-0"
67150
61220
126-111
6
31'-8"
24'-0"
77960
72115
127-111
7
31'-8"
28'-0"
88850
83590
NOTE 1 U se this bulletin for preliminary layouts only. Obtain current drawings from your Marley sales representative. 2 Steel beams must include 7⁄8" dia. holes to accept anchor bolts provided with tower. Other contractors or purchaser must design and erect supporting steel.
3 M aintain at least 2'-0" of clear space at tower endwalls for construction purposes. Air inlet faces must have unobstructed air supply. If obstructions exist nearby, consult your Marley sales representative. 4 Operating weight is wet weight of tower and steel basin, including 6" of water in the cold water basin. 5 View shown is typical single cell beam arrangement.
Marley / Sigma Steel Cooling Tower / Engineering Data : Concrete Basin W
6" MIN.
6" MIN.
IN TO IN OF BASIN
6" MIN.
5"
AIR INLET FACE
ANCHOR BOLTS (SEE NOTE 5)
SUMP
A SPACES AT 4'-0" = L PER CELL
AIR INLET FACE
CASED ENDWALL FACE
CASED ENDWALL FACE
6" MIN.
5"
Plan RECOMMENDED OPERATING WATER LEVEL 1'-6"
1'-0
Section Tower Model
Operating Weight lb
Dimensions A
W
L
Single Fan Cell
Each Cell Add
121-111
3
23'-6"
12'-0"
25200
21525
122-111
4
25'-6"
16'-0"
32280
28430
123-111
4
27'-6"
16'-0"
33300
29080
124-111
5
27'-6"
20'-0"
39230
35025
125-111
5
31'-6"
20'-0"
42800
37715
126-111
6
31'-6"
24'-0"
48780
43910
127-111
7
31'-6"
28'-0"
54830
50550
NOTE 1 Use this bulletin for preliminary layouts only. Do not use for construction. Obtain current drawings from your Marley sales representative. Concrete basin design and construction are by other contractors or purchaser. 2 Operating weight is total wet operating weight of tower only, excluding water in concrete basin. 3 Maintain at least 2'-0" of clear space at tower endwalls for construction purposes. Air inlet faces must have unobstructed air supply. If obstructions exist nearby, consult your Marley sales representative.
4 Minimum basin depth is 1'-6". Basin depth may vary to suit your storage requirements. 5 All anchor bolts complete with nut and washer must be furnished by others. Bolts must be 3⁄4" diameter with 11⁄2" all-thread projection. 6 Other contractors or purchaser must design, locate, construct, and furnish sump(s) and overflow(s) to suit requirements. The sump(s) should be designed according to the pump manufacturer’s recommendations. Other design sources: ANSI/HI specifications 1.1-1.5 for centrifugal pumps, 2.1-2.5 for vertical pumps, and 9.8 for pump intake design.
8
Marley / Sigma Steel Cooling Tower / Engineering Data : Inlet Piping C
CL FAN CL INLET
D
CL FAN CL INLET
TYP. MULTICELL
C CL COLUMN AND ANCHOR BOLT
CL
F MIN REQUIRED CLEARANCE
TYP. SINGLE CELL CL COLUMN AND ANCHOR BOLT
9
B DIA FLOW
FACE OF A DIA INLET FLANGE
E
CL FAN CL TOWER
MARLEY PIPING STOPS HERE
CL
CONTROL VALVE
G CL OF FLANGE TO
BASE OF TOWER COLUMNS (USE FOR STATIC LIFT)
Tower Model
GPM per cell
Dimensions A
B
500-3800
10"
8"
3801-4500
12"
10"
122-111
650-6000
14"
123-111
650-6000
121-111
C
D
E
F
8'-10 ⁄2"
G
1
14'-63⁄4"
6'-0"
12'0"
10"
8'-0"
16'-0"
10'-0 ⁄2"
14'-1 ⁄4"
14'-73⁄4"
14"
10"
8'-0"
16'-0"
11'-01⁄2"
15'-11⁄4"
14'-73⁄4"
1000-6000
14"
10"
6001-7500
16"
12"
125-111
1000-7500
16"
126-111
1000-9000
127-111
1500-10500
124-111
9'-01⁄2" 1
11'-0 ⁄2"
13'-11⁄4" 1
1
15'-11⁄4"
14'-73⁄4"
14'-73⁄4"
10'-0"
20'-0"
12"
10'-0"
20'-0"
13'-1 ⁄2"
17'-1 ⁄4"
14'-83⁄4"
16"
12"
12'-0"
24'-0"
13'-11⁄2"
17'-11⁄4"
14'-83⁄4"
18"
14"
14'-0"
28'-0"
13'-5 ⁄8"
17'-1 ⁄4"
14'-93⁄4"
11'-11⁄2" 1
5
1
1
14'-83⁄4"
NOTE 1 Use this bulletin for preliminary layouts only. Obtain current drawings from your Marley sales representative. 2 Pumping head contributed by the tower is static lift “G”. Actual pumping head will vary according to tower circulating GPM. Total pumping head will be furnished at time of proposal. 3 If your application requires a bypass system, recommended location is through tower endwall into plenum area. Review of the system by SPX engineering is required.
4 Marley piping terminates at face of a cast iron flat face flange. Bolt circle conforms to class 125 lb. ANSI B 16.1 specifications. 5 Supports on tower for crossover piping are part of the tower design. Do not support the riser’s dead load or operating load from the tower. Do not brace the riser’s seismic or thrust loads against the tower. 6 Butterfly valves or piping expansion joints (if used) are by others and must be located outside the limits of the cooling tower “F”. 7 Motor must be located 180° from inlet.
Marley / Sigma Steel Cooling Tower / Engineering Data: Environmental
10
Sound Control Sound produced by a Sigma Steel tower operating in an unobstructed environment will meet all but the most restrictive noise limitations—and will react favorably to natural attenuation. Where the tower has been sized to operate within an enclosure, the enclosure itself will have a damping effect on sound. Sound also declines with distance—by about 5 dBA each time the distance doubles. Where noise at a critical point is likely to exceed an acceptable limit, several options are available—listed below in ascending order of cost impact: • In many cases, noise concerns are limited to nighttime, when ambient noise levels are lower and neighbors are trying to sleep. You can usually resolve these situations by using two-speed motors in either 1800/900 or 1800/1200 RPM configuration—operating the fans at reduced speed without cycling “after hours”. The natural nighttime reduction in wet-bulb temperature makes this a very feasible solution in most areas of the world, but the need to avoid cycling may cause the cold water temperature to vary significantly. • The Marley Variable Frequency Drive automatically minimizes the tower’s noise level during periods of reduced load and/or reduced ambient temperature without sacrificing the system’s ability to maintain a constant cold water temperature. This is a relatively inexpensive solution, and can pay for itself quickly in reduced energy costs. • Where noise is a concern at all times—for example, near a hospital—the best solution is to oversize the tower so it can operate continuously at reduced (1200 or 900 RPM) motor speed. Typical sound reductions are 7 dBA at 2/3 fan speed or 10 dBA at half fan speed. • Extreme cases may require inlet and discharge sound attenuator sections—however, the static pressure loss imposed by attenuators may necessitate an increase in tower size. This is the least desirable approach because of the significant cost impact—and because of the obstruction to normal maintenance procedures.
As suggested in the aforementioned Technical Report, it may also be advisable to specify a design wet-bulb temperature 1°F higher than normal to compensate for potential recirculation initiated by the enclosure. You’ll benefit from discussing your project with your Marley sales representative. Keeping It Clean Cooling towers are very effective air washers. Atmospheric dust able to pass through the relatively small louver openings will enter the circulating water system. Increased concentrations can intensify system maintenance by clogging screens and strainers—and smaller particulates can coat system heat transfer surfaces. In areas of low flow velocity— such as the cold water basin—sedimentary deposits can provide a breeding ground for bacteria. In areas prone to dust and sedimentation, you should consider installing some means for keeping the cold water basin clean. Typical devices include side stream filters and a variety of filtration media. Water Treatment Contaminants including Legionella, an effective consistent water treatment program is required. Controlling blowdown may be adequate in mitigating the potential of corrosion and scale, but biological contamination can only be controlled with biocides. An acceptable water treatment program must be compatible with the variety of materials incorporated in a cooling tower—ideally the pH of the circulating water should fall between 6.5 and 8.0. Batch feeding of chemicals directly into the cooling tower is not a good practice since localized damage to the tower is possible. Specific startup instructions and additional water quality recommendations can be found in the Sigma User Manual which accompanies the tower and also is available from your local Marley sales representative. For complete water treatment recommendations and services, contact your local Marley sales representative.
Your Marley sales representative will help you meet your sound requirements. Enclosures Occasionally, cooling towers are located inside architectural enclosures for aesthetic reasons. Although Sigma towers adapt well to enclosures, the designer must realize the potential impact of a poorly arranged enclosure on the tower’s performance and operation. The designer must take care to provide generous air inlet paths, and the tower’s fan cylinder discharge height should not be lower than the elevation of the top of the enclosure. Obtain a copy of Marley Technical Report #H-004, “External Influences on Cooling Tower Performance” from your Marley sales representative or on the web at spxcooling.com.
CAUTION The cooling tower must be located at such distance and direction to avoid the possibility of contaminated discharge air being drawn into building fresh air intake ducts. The purchaser should obtain the services of a Licensed Professional Engineer or Registered Architect to certify that the location of the cooling tower is in compliance with applicable air pollution, fire and clean air codes.
Marley / Sigma Steel Cooling Tower / Engineering Data: Energy Management
Cooling towers are usually selected to produce a specific cold water temperature at the higher summertime wet-bulb temperatures. During the remainder of the year, the cooling tower is capable of producing much colder water. Unless your system will benefit from the coldest possible water temperature, you should consider controlling cold water temperatures to higher levels. You’ll also save energy by using such control. For greater insight on cold water temperature control, please read “Cooling Tower Energy and its Management”, Technical Report #H-001A, available from your Marley sales representative or on the web at spxcooling.com. Always control leaving water temperature by manipulating the quantity of air that the fan moves through the tower. Varying the quantity of water flow is not normally recommended and can be harmful in freezing weather. You can alternately start and stop single-speed motors to maintain water temperatures within an acceptable range. However, exceeding a total acceleration time of 30 seconds per hour can overheat the motor, causing the insulation to fail. Limiting the number of motor starts, on the other hand, can produce significant variations in the temperature of the water delivered to the process. Increased flexibility can simplify your operating procedures and save you money in the long run, both on operation and on maintenance. Here are two of the more popular options. Two-Speed Motors Two-speed motors improve operating flexibility by increasing the number of potential operating modes. Users in northern climates will find that the tower can carry winter loads at half-speed; reducing fan power requirements by 85+% during that time. Two-speed motors also help to control icing during wintertime operation. See Marley Technical Report #H-003, “Operating Cooling Towers During Freezing Weather”, available from your Marley sales representative or on the web at spxcooling.com.
11
Normally, two-speed motors are provided in 1800/900 RPM, single winding configuration, which is the least expensive two-speed option. They are also available in other combinations including the more expensive double winding. Variable Speed Fan Drive Frequency modulation devices work well on induced draft, propeller fan cooling towers such as the Sigma Steel cooling tower. However, their design must include the capability to lock out any critical fan speeds and the very low fan speed ranges. Marley VFD drive systems are designed to combine absolute temperature control with ideal energy management. The cooling tower user selects a cold water temperature and the drive system will vary the fan speed to maintain that temperature. Precise temperature control is accomplished with far less stress to the mechanical equipment components. The improved energy management provides fast payback. Indeed, many utilities offer generous rebates for users having installed VFD drives.
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications 1.0
Base:
1.1
Furnish and install an induced-draft, crossflow-type, field-erected, steelframed, PVC-fill, industrial-duty cooling tower of _____ cell(s), as shown on Plans. The limiting overall dimensions of the tower shall be _____ wide, _____ long, and _____ high to the top of the fan cylinder. Total operating horsepower of all fans shall not exceed ____ hp, consisting of ___ @ _____ hp motor(s). Tower shall be similar and equal in all respects to Marley Model _______.
12
Specification Value
■ Your specification base establishes the type, configuration, base material, 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 hp/cell will work to your advantage. Crossflow towers are noted for the accessibility and maintainability of all operating components. The spacious interior provides easy access to fill, drift eliminators, all basin accessories — and is one of two primary access ways to the fan, Geareducer, and other mechanical components. At the fan deck level, the hot water distribution basins are easily inspected and cleaned — while the tower is operating, if you wish. The mechanical equipment can also be readily accessed from this level. Except for the cold water basin, no counterflow tower component requiring routine maintenance is as easily accessed. The confined areas that typify counterflow designs can make difficult work for maintenance personnel!
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications 2.0
Thermal Performance:
2.1
The tower shall be capable of cooling _____ GPM of water from ____ °F to _____ °F at a design entering air wetbulb temperature of _____ °F. The cooling tower manufacturer shall guarantee that the tower supplied will meet the specified performance conditions when the tower is installed according to plans.
Specification Value ■Y our reason for purchasing a cooling tower is to obtain a continuing flow of cooled water as defined in the first paragraph at left. If the tower that you purchase is incapable of performing as specified, then you will not have received full value for your money. Bear in mind that the size—and cost—of a cooling tower varies directly with its true thermal capability. This paragraph is intended to protect you against either intentional or inadvertent under sizing of the tower by the manufacturer. Judging the level of performance of a cooling tower on critical processes is never easy, and the potential risk of a non-performing cooling tower usually causes the requirement for a mandatory acceptance test to be very desirable.
The purchaser will arrange for an on-site thermal performance test, to be conducted in the presence of the manufacturer and owner, and under the supervision of a qualified, disinterested third party in accordance with CTI (Cooling Technology Institute) ATC105 standards during the first full year of operation. If the tower fails to perform within the limits of test tolerance, then the cooling tower manufacturer will install additional cells and/or make such corrections as are agreeable to the owner and shall pay for the cost of a retest. If the tower still fails to perform as specified, then the manufacturer shall make such reimbursements as are appropriate and agreeable to the owner to compensate for the performance deficiency.
Your contract with the successful bidder should establish the acceptable remedies for missed performance, which might include: • The addition of one or more cells of tower, as necessary, to bring the cooling tower to the specified level of performance. This is usually limited to the scope of work as defined in the specs, which means that you (the owner) will have to pay for the additional basin, wiring, starters, piping, etc. • The reimbursement of a portion of the total contract price equal to the percentage deficiency in performance. U nder no circumstances should you allow the manufacturer to re-pitch the fans to increase motor brake horsepower above that shown in the proposal. That creates additional operating costs that will continue for the life of the tower—and imposes no penalty on the manufacturer. 95°
90°
85° COLD WATER TEMP. (°F)
2.2
13
80° 5°F RANGE 10°F RANGE 15°F RANGE
75°
70°
65°
60°
55° 50°
55°
60°
65°
70°
WET BULB TEMP. (°F)
Typical cooling tower performance curve.
75°
80°
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications 3.0
Construction:
3.1
The tower shall be capable of withstanding water having a pH of 6.5 to 8.0; a chloride content (NaCl) up to 300 ppm; a sulfate content (SO4 ) up to 250 ppm; a calcium content (CaCO3) up to 500 ppm; silica (SiO2) up to 150 ppm; and design hot water temperatures up to 120°F. The circulating water shall contain no oil, grease, fatty acids, or organic solvents.
3.2
The structural framework of the tower, as well as all basins and decking, shall be of heavy gauge cold-formed steel and/or mill shapes, hot-dip galvanized after fabrication to a deposition of at least 2.25 ounces of zinc per square foot.
3.3
Column lines shall be on no greater than 4' longitudinal centers, and the base of all columns shall be firmly anchored. Basic design criteria shall be 30 psf wind load and 5%g seismic load. Framing joints shall be made with 1⁄2" diameter and larger Series 300 stainless steel machine bolts, nuts and washers.
3.4
Towers of more than one cell shall include galvanized internal partitions to separate the fan plenums, and a hinged access door shall be provided in each partition for freedom of access throughout the tower.
14
Specification Value ■T he limiting water quality values indicated are those which are acceptable for the normal materials of construction specified. If water of more aggressive quality is anticipated, consider specifying a stainless steel Sigma tower. See page 27.
■H ot-dip galvanizing after fabrication assures that all steel surfaces will be heavily coated with zinc. All shearing, bending, drilling, punching, etc. will have been completed prior to galvanization.
ulticell towers must have plenum partitions between cells. Otherwise, ■M air will be induced downward through an inoperative fan, bypassing the fill entirely. Without these partitions, part-load or off-season operation of the tower would be completely unsatisfactory.
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications
Specification Value
4.0
Fan Deck and Fan Cylinder:
4.1
The fan deck shall act as a working platform for maintenance personnel. It shall be fabricated of no less than 12 gauge steel, and shall be designed for a uniform live load of 60 psf.
4.2
Fan cylinders shall be molded FRP. They shall be through-bolted 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, incorporating heavy duty blades of cast aluminum or high strength, inert composite material. Blades shall be individually adjustable and replaceable. Fan(s) shall be driven through a rightangle, industrial-duty, oil-lubricated, geared speed reducer. Speed reducers employing pulleys and belts will not be accepted.
■ Propeller-type fans require only half the operating HP of blower-type fans.
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.
■ 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).
5.2
15
■ 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. ■F iberglass-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. Their 6' to 7' height also provides protection for operating personnel.
They should be readily adjustable to permit compensation for job site conditions that may tend to overload the motor. The fans of one manufacturer require the purchase of special positioners for each increment of fan blade pitch. 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 at least two other cooling tower manufacturers.
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications
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 balanced driveshaft equipped with neoprene flexible coupling elements.
5.4
A galvanized oil gauge and drain line shall extend from the gear reducer to the vicinity of the motor, and shall be equipped with a dip stick for oil level measurement.
5.5
5.6
16
Specification Value
■ 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.
The complete mechanical equipment assembly for each cell shall be supported by a rigid, unitized support that resists misalignment between the motor and the gear reducer. Support shall be heavy-wall tubular steel, to which heavy plate platforms for the motor and gear reducer have been welded and the assembly shall be hotdip galvanized after fabrication. The support assembly shall also provide an inlet connection for incoming hot water, and shall serve as a crossover pipe to deliver water to both sides of the tower.
■ Fans of the size used on large cooling towers are applied at speeds and horsepower that generate considerable torque—and structural tubular steel resists this torque very effectively. Marley torque-tube assures that all of the mechanical equipment remains aligned, and that the rotating fan is properly positioned within the fan cylinder.
The mechanical equipment assembly shall be warranted for no less than five (5) years. This warranty shall cover the fan(s), speed reducers, driveshafts and couplings, and the unitized supports.
■ The value of a 5 year mechanical equipment warranty speaks for itself. Except for the motor, all of the mechanical equipment on a Marley tower is made by SPX Cooling Technologies. Cooling tower vendors who purchase commercial fans, gear boxes, driveshafts, etc. may require that you deal directly with those commercial suppliers for warranty satisfaction.
Marley / Sigma Steel Cooling Tower / Specifications: Base
17
Specification Value
Specifications 6.0
Fill, Louvers and Drift Eliminators:
6.1
Fill shall be film-type, 15 mil thick, thermoformed PVC, with louvers formed as part of each fill sheet. Fill shall be suspended from stainless steel structural tubing supported from the upper 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.
■ 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. If you plan to use your tower in the wintertime, particularly for free cooling, integral louvers will put your operating concerns to rest.
6.2
Drift eliminators shall be PVC, triplepass, and shall limit drift losses to 0.005% or less of the design water flow rate.
■ Vertical blade-type eliminators, as well as misdirected cellular types, cause much of the fan power to be wasted in turning the horizontal flow of air vertical for its exit through the fan cylinder. This power is, of course, not available for contribution to thermal performance. 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.
Drift Eliminator Section
Louver Section
Fill Section
Marley / Sigma Steel Cooling Tower / Specifications: Base
18
Specification Value
Specifications 7.0
Hot Water Distribution System:
7.1
The mechanical equipment support/ crossover pipe shall deliver water to two open hot water basins per cell at the fan deck elevation. Water shall exit these basins to the fill by gravity through metering orifice-type polypropylene nozzles situated in the basin floor. Nozzles shall be easily removable and replaceable.
7.2
Heavy-duty, industrial grade flowcontrol valves shall be provided at the inlet to each basin. These valves shall permit both flow balancing and maintenance shut-off to selected cells, or portions of cells. Valves shall have machined cast iron bodies, with stainless steel operating stems, and heavyduty locking handles.
8.0
Casing:
8.1
Tower endwalls shall be cased with corrugated FRP panels, attached with corrugations running vertically and overlapped one corrugation at joints. Tower corners shall be finished with FRP corner rolls over the ends of the casing sheets.
8.2
In the water-washed fill areas, inner casings of 16 gauge galvanized steel shall also be provided.
9.0
Access:
9.1
There shall be a 33" wide by 61" high access door in each endwall casing to provide access to the interior of the tower. Access doors shall be hinged and equipped with a latch operable from both inside and outside the tower. Internal partitions between cells shall include hinged doors to give free access through the tower.
➠
distribution basins are a feature ■ Gravity-flow of crossflow type towers. These basins are out where they can be easily inspected—even maintained—while the tower is in operation. Spray systems of counterflow towers, sandwiched between the top of the fill and the drift eliminators, are extremely awkward to access and maintain. ■ Marley flow-control valves remain serviceable for the life of the tower, and provide a continuing means of flow-regulation between hot water basins—and between cells of multicell towers as well. Towers without valves do not provide this valuable operating flexibility.
■ Steel inner casings provide lateral support for the fill that FRP panels cannot. They also support the FRP casing panels against the high wind loads that will act on the tower during its lifetime.
■ The access doors on other towers may be unreasonably small. Specifying the size of the door will cause those bidders to take excep-
Marley / Sigma Steel Cooling Tower / Specifications: Base
Specifications
9.2
The top of the tower shall be equipped with a sturdy 42" high guardrail system, complete with top rails, intermediate rails and toeboards, conforming to OSHA standards. Guardrails and posts shall consist of 1.66" O.D. x 15 gauge galvanized structural tubing. Posts shall be spaced on centers of 8'0" or less.
9.3
One endwall of the tower shall be equipped with a 20" wide aluminum vertical ladder, through-bolted to the endwall structure. Ladder shall rise from the cold water basin level to the top of the fan deck guardrail, and shall be designed and installed in conformance with OSHA standards.
19
Specification Value
tion, alerting you to a potential maintenance headache. ■ Good maintenance practice requires periodic access to the top of the tower to inspect the distribution basins, as well as the structural integrity of the fan deck, fan cylinder, and fan — especially the fan blade securing hardware. There are no induced-draft cooling tower designs that are immune to this need!
■ For the comfort and safety of your operating personnel, the Sigma Steel tower includes a ladder and guardrail of the quality and design indicated — and we strongly recommend that you require it of all bidders! Portable ladders and other "make-do" access means are inappropriate for equipment of this size and complexity.
10.0 Cold Water Collection Basin: 10.1 The collection basin shall be heavygauge galvanized steel and shall include the number and type of suction connections required to accommodate the out-flow piping system shown on the plans. Suction connections shall be equipped with debris screens. A factory installed, float operated, mechanical make-up valve shall be included. An overflow and drain connection shall be provided in each cell of the tower. The basin floor shall slope toward the drain to allow complete flush out of debris and silt which may accumulate.
■ This basic specification assumes that the tower will be erected over a concrete basin at grade level. If the tower is to be installed on an elevated supporting platform, the steel cold water collection basin indicated on page 24 should be included in the specifications.
11.0 Scope of Work: 11.1 The cooling tower manufacturer shall be responsible for the design, fabrication, and delivery of materials to the project site, and for the erection of the tower over supports provided by others. Unless otherwise specified, all external piping, pumps, controls, and electrical wiring will be outside the cooling tower manufacturer's scope of work.
■ Please be clear in your specifications and inquiry documents regarding the full scope of work expected. That will help assure that your bid comparisons will be made on as equal a basis as possible—and will help to avoid any misunderstandings during
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Control Options
Control System: 5.7: Add the following paragraph in the Mechanical Equipment section: Each cell of the cooling tower shall be equipped with a UL listed control system in a NEMA 3R or 4X outdoor enclosure capable of controlling single-speed or two-speed motors as required, and designed specifically for cooling tower applications. The panel shall include a main fused disconnect with an external operating handle, lockable in the off position for safety. Across-the-line magnetic starters or solid state soft-start starters as required shall be controlled with a thermostatic or solid state temperature controller. Door mounted selector switches shall be provided to enable automatic or manual control and wired for 120VAC control. Control circuit to be wired out to terminal blocks for field connection to a remote vibration switch and for access to extra 120VAC 50VA control power, overload trip alarms and remote temperature control devices. The temperature controller shall be adjustable for the required cold water temperature. If a thermostatic controller is used it shall be mounted on the side of the tower with the temperature sensing bulb installed in the cold water basin using a suspension mounting bracket. If a solid state temperature controller is used the controller will be door mounted on the control panel. The temperature controller will display two temperatures, one for outgoing water and the other for set point. Water temperature input shall be obtained using a three-wire RTD with dry well in the outlet water piping and wired back to the solid state temperature controller in the control panel.
20
Specification Value the execution and implementation of the contract.
■ If it is your opinion that the control system for the cooling tower should be part of the tower manufacturer’s responsibility, we are in wholehearted agreement with you. Who better to determine the most efficient mode and manner of a tower’s operation—and to apply a system most compatible with it—than the designer and manufacturer of the cooling tower?
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specification Value
Specifications
21
Basin Heaters:
10.2 Add the following paragraph in the Cold Water Basin section: Provide a system of electric immersion heaters and controls for each cell of the tower to prevent freezing of water in the collection basin during periods of shutdown. The system shall consist of one or more stainless steel electric immersion heaters installed in the basin. A NEMA 4 enclosure shall house a magnetic contactor to energize heaters; a transformer to provide 24 volt control circuit power; and a solid state circuit board for temperature and low water cutoff. A control probe shall be located in the basin to monitor water level and temperature. The system shall be capable of maintaining 40°F water temperature at an ambient air temperature of __ °F.
Fan Motor Variable Speed Drive:
Marley All Weather ACH550 System
6.4
Add the following paragraph in the Mechanical Equipment section when VFD is used with customers Building Management System: A complete UL listed Variable Speed Drive system in a NEMA 1 indoor, NEMA 12 indoor or NEMA 3R outdoor enclosure shall be provided. The VFD shall use PWM technology with IGBT switching and integrated bypass design. VFD out put switching shall not cause mechanical issues with gearbox teeth or drive shafts. The VFD shall catch a fan spinning in the reverse direction without tripping. The panel shall include a main disconnect with short circuit protection and external operating handle, lockable in the off position for safety. The VFD system shall receive a speed reference signal from the Building Management System monitoring the tower fluid temperature. As an option to receiving the speed reference signal from a building management system, the drive must have the capability to receive a 4-20 ma temperature signal from an RTD transmitter. The VFD shall have an internal PI regulator to modulate fan speed maintaining set point temperature. The drive's panel display shall be able to display the set-point
➠
■ The basin heater components described at left represent our recommendation for a reliable automatic system for the prevention of basin freezing. They are shipped separately for installation at the job site. The ambient air temperature that you fill in should be the lowest 1% level of winter temperature prevalent at site.
■ Marley VFD drive systems are designed to combine absolute temperature control with ideal energy management. The cooling tower user selects a cold water temperature and the drive system will vary the fan speed to maintain that temperature. Precise temperature control is accomplished with far less stress to the mechanical equipment components. The improved energy management provides fast payback. Indeed, many utilities offer generous rebates for users having installed VFD drives.
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications temperature and cold-fluid temperature on two separate lines. The bypass shall include a complete magnetic bypass circuit and with capability to isolate the VFD when in the bypass mode. Transfer to the bypass mode shall be manual in the event of VFD failure. Once the motor is transferred to the by-pass circuit the fan motor will run at constant full speed. The bypass circuit will not modulate ON and OFF based on fluid temperature. The application must be able to handle very cold fluid temperatures while the VFD is in a by-pass mode. Operator controls shall be mounted on the front of the enclosure and shall consist of start and stop control, bypass/VFD selection, Auto/ Manual selections, manual speed control. To prevent heating problems in the fluid cooloer fan motor and to assure proper gear reducer lubrication the VFD system shall de energize the motor once 25% motor speed is reached and cooling is no longer required. The fluid cooler manufacturer shall supply VFD start-up assistance. Tower vibration testing throughout the speed range is required to identify and lockout any natural frequency vibration levels which may exceed CTI guidelines.
Marley Premium VFD System
6.4
Add the following paragraph in the Mechanical Equipment section when VFD is used as a stand alone system: A complete UL listed Variable Speed Drive system in a NEMA 12 indoor or NEMA 3R outdoor enclosure shall be provided. The VFD shall use PWM technology with IGBT switching and integrated bypass design. VFD output switching shall not cause mechanical issues with gearbox teeth or drive shafts. The VFD shall catch a fan spinning in the reverse direction without tripping. The panel shall include a main disconnect with short circuit protection and external operating handle, lockable in the off position for safety. The system shall include a solid state, PI temperature controller to adjust frequency output of the drive in response to the tower fluid temperature. The temperature of the fluid and set point shall be displayed on the door of the control panel. The bypass shall include a complete magnetic bypass
Specification Value
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Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Specification Value
circuit with capability to isolate the VFD when in the bypass mode. Transfer to the bypass mode shall be automatic in the event of VFD failure or for specific trip conditions allowing safe transfer of utility voltage to the motor. Automatic bypass with an earth ground condition is not allowed. The bypass contactor shall be cycled on and off while operating in bypass, to maintain the set-point temperature of the cold water. The drive design shall be operated as a stand-alone system 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 fluid cooler fan motor to be run at full speed shall be furnished. To prevent heating problems in the fluid cooler 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 fluid cooler manufacturer shall supply VFD start-up assistance. Tower vibration testing throughout the speed range is required to identify and lockout any natural frequency vibration levels which may exceed CTI guidelines.
Vibration Limit Switch:
5.8
Add the following paragraph in the Mechanical Equipment section: A single-pole, double-throw vibration limit switch in a NEMA 4 housing shall be installed on the mechanical equipment support for wiring into the owner’s control panel. The purpose of this switch will be to interrupt power to the motor in the event of excessive vibration. It shall be adjustable for sensitivity, and shall require manual reset.
■ Unless specified otherwise, a Marley M-5 vibration switch will be provided. The requirement for manual reset assures that the tower will be visited to determine the cause of excessive vibration.
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Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Convenience and Safety Options
Stairway:
9.3
Replace paragraph 9.3 with the following: A 30" wide, 45° steel stairway with 8" rise and run, shall be provided at the tower endwall rising from grade (roof) to the fan deck elevation. Stair treads shall be bar grating with checker plate nosing, and shall be through bolted to structural channel stringers. Stairway posts, guardrails and toeboards shall be as specified per Paragraph 9.2. Structural steel support columns for the stairway shall be provided by the cooling tower manufacturer. Stairway foundation shall be by others, designed in accordance with drawings provided by the cooling tower manufacturer. The entire stairway shall be hot-dip galvanized after fabrication and shall conform to OSHA standards.
Plenum Walkway:
9.1
Add the following to the end of this paragraph: Provide a 30" wide bar grating walkway extending from one endwall access door to the other in each cell. This walkway shall be supported by a galvanized steel framework, and the top of the grating shall be above the cold water basin overflow level. If the cold water basin is deeper than 4'-0", the walkway shall be equipped with guardrails.
Ladder Extension:
9.4
Add the following paragraph in the Access and Safety section: Provide a ladder extension for connection to the base of the ladder attached to the tower casing. This extension shall be long enough to rise from the roof (grade) level to the base of the tower. Anchorage and lateral bracing of the ladder extension shall be by others.
Ladder Safety Cage:
9.3
Add the following to the end of this paragraph: A heavy gauge galvanized steel safety cage shall surround the ladder, extending from a point approximately 7'-0" above the base of the ladder to the top of the guardrail surrounding the fan deck.
24
Specification Value
■ Although they are not necessary for routine operation and maintenance, stairways do provide a safe and comfortable means of access to the top of the tower that is often overlooked in the initial cooling tower purchase. They are designed in straight-run or double-back configurations to accommodate your site requirements.
■ This option permits freedom of movement for inspection or maintenance within the tower without the need for wading boots or tower drainage. It also helps prevent maintenance personnel from damaging submerged accessories in the cold water basin (such as screens, probes, basin heaters, etc.).
■ Many towers are installed such that the base of the tower is 2'-0" or more above the roof or grade level. This makes it difficult to get up to the base of the attached ladder. The ladder extension alleviates this problem. Marley ladder extensions are available in standard 5'-0" and 11'-0" lengths, and will be field-cut to fit.
■ To meet OSHA guidelines, towers whose fan decks are 20'-0" or more above roof or grade, and which are equipped with ladders, are required to have safety cages surrounding the ladders.
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Oil Level Sight Glass:
5.4
Replace paragraph 5.4 with the following: A galvanized oil gauge and drain line shall extend from the gear reducer to the vicinity of the motor, and shall be equipped with a bronzebodied oil level sight glass.
Miscellaneous Options
Steel Cold Water Basin:
10.1 Replace paragraph 10.1 with the following: Include a cold water collection basin constructed of 12 gauge hot-dip galvanized formed steel sheets. These sheets shall be bolted, gasketed and caulked to form a watertight basin 18" deep. A depressed, side outlet sump shall be included, having a 1/4" thick faceplate drilled for a standard 125# flange connection. An appropriately sized (3" diameter or larger) galvanized standpipe overflow shall be provided. The standpipe shall be removable for flush-out cleaning of the basin. A float-operated, mechanical makeup valve shall also be included, installed adjacent to the endwall access door.
Factory Mutual Approval:
3.5
Add the following paragraph in the Construction section: 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.
Hot Water Basin Covers:
7.3
Add the following paragraph to the Hot Water Distribution System Section: The distribution basins shall include galvanized steel covers. These covers shall be designed for a uniform live load of 40 psf, and shall be easily removable for maintenance.
Air Inlet Screens:
8.3
Add the following paragraph to the Casing Section: The air inlet faces of the tower shall be covered by 1" mesh hot-dip galvanized welded wire screens. Screens shall be mounted in galvanized steel U-edging and shall be removable.
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Specification Value ■ The oil level sight glass is a convenience item that is preferred by many users. The same purpose is, of course, served by either the dip stick or the sight glass.
■ Marley basins are used to permit the installation of towers on elevated platforms or foundations. This is the simplest of several cold water basin designs available for the Sigma Steel towers. Because of its bolted construction, it has the advantage of being hot-dip galvanized after fabrication. Marley can also install a 10 gauge welded stainless steel basin for a Stainless Steel Sigma. See 24.
■ 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.
■ These covers are designed to keep leaves and debris out of the circulating water system. They also serve to suppress algae formation by shielding the incoming hot water from direct sunlight.
■ In wooded or windy areas, these screens help to keep leaves or blowing debris out of the cooling tower and circulating water system.
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Low Noise Tower:
1.1
Add the following at the end of this paragraph: The cooling tower shall be quiet operating, and shall produce an overall level of sound no higher than ____ dBA at the critical location indicated on the Plans.
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Specification Value ■ Sound produced by a Sigma Steel tower operating in an unobstructed environment will meet all but the most restrictive noise limitations – and will react favorably to natural attenuation. Where the tower has been sized to operate within an enclosure, the enclosure itself will have a damping effect on sound. Sound also declines with distance – by about 5 or 6 dBA each time the distance doubles. Where noise at a critical point is likely to exceed an acceptable limit, you have several options – listed below in ascending order of cost impact: • Where only a slight reduction in noise will satisfy — and the source of concern is in a particular direction — merely turning the tower may be the answer. Less sound emanates from the cased face of the tower than does from the air intake face. • In many cases, noise concerns are limited to nighttime, when ambient noise levels are lower and neighbors are trying to sleep. You can usually resolve these situations by using two-speed motors in either 1800/900 or 1800/1200 RPM configuration; and operating the fans at reduced speed without cycling “after hours”. (The natural nighttime reduction in wet-bulb temperature makes this a very feasible solution in most areas of the world, but the need to avoid cycling may cause the cold water temperature to vary significantly.) • Variable speed drives automatically minimize the tower's noise level during periods of reduced load and/or reduced ambient without sacrificing the system's ability to maintain a constant cold water temperature. This is a relatively inexpensive solution, and can pay for itself quickly in reduced energy costs. • Where noise is a concern at all times (for example, near a hospital), the best solution is to oversize the tower so it can operate continuously at reduced (1200 or 900 RPM) motor speed even at the highest design wet-bulb temperature. Typical sound reductions are 7 dBA at 2/3 fan speed or 10 dBA at 1/2 fan speed, but larger reductions are often possible. •E xtreme cases may require inlet and discharge sound attenuator sections; however, the static pressure loss imposed by attenuators may necessitate an increase in tower size. This is the least desirable approach because of the significant cost impact – and because of the obstruction to normal maintenance procedures. our Marley representative can help you meet your sound requireY ments.
Marley / Sigma Steel Cooling Tower / Specifications: Options
Specifications
Service Life-Related Customization:
27
Specification Value ■ Some adverse water conditions, unsatisfactory air quality, and/or processes that produce corrosive contaminants, may dictate the use of stainless steel for materials of construction in the tower. Refer to our Stainless Steel Sigma Series, in which the use of stainless steel has been maximized. Except for valve bodies and Geareducer, every steel component of that product line is manufactured of stainless steel. If your project has a need for the extended service life that premium materials will offer, please obtain a copy of "Marley Sigma Stainless Steel Cooling Tower Specifications" from your local Marley sales representative, and extract from it those paragraphs that make sense for you.
