Marley Sigma F Series Cooling Tower
Contents
1. C D TYP SINGLE CELL ee TYP MULTICELL FAN INLET INLET COLUMN AND i COLUMN AND ANCHOR BOLT If ANCHOR BOLT i 1 lu 1 TA L oe z E F Zz ic lt PIPING PIPING LOADS SUPPORTED 4 LOADS SUPPORTED PLAN ANSI SPECIFICATIONS BY TOWER BY OTHERS B DIAMETER FAN amp ad CROSSOVER PIPE INLET MOTOR ee ene OPS rere FACE OF A DIA GALVANIZED FLANC T FLANGE IS 3 4 THICK BOLT 2 1 CIRCLE CONFORMS TO 125 LB l i l i I BASE OF TOWER COLUMNS i I i I i l E NOTE 1 Use this bulletin for preliminary layouts only Obtain current drawings from your Marley representative 2 Pumping head contributed by the tower is static lift E Actual pumping head will vary according to tower circulating GPM Total pumping head will be furnished at time of proposal E 3 If your application requires a bypass system recommended STAINLESS CONCRETE location is through the tower endwall into the plenum area STEEL BASIN BASIN OPTION Review of the system by SPX engineering is required OPTION 4 All header and riser piping to be furnished by others END ELEVATION A corrosion resistant material or coating for piping is recommended All inlet piping loads including thrust and seismic out2. E Marley VFD drive systems are designed to combine absolute temperature control with ideal energy management The cool ing 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 F Series Cooling Tower Specifications Options m Specification Value 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 natu ral frequency vibration levels which may exceed CTI guidelines Marley Premium VFD System 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
3. roof to the fan deck Treads stringers and risers shall be molded integrally for strength and stiffness Stairs shall be 41 5 30 762 mm wide with 8 203 mm rise and 9 229 mm run Treads shall have a nonskid surface Landings shall occur at 6 0 1 83 m elevations Guardrails shall be 2 tubes through bolted to 3 tube stairway columns Stairway foundation shall be by others designed in accordance with drawings provided by the cooling tower manu facturer The stairway shall conform to OSHA standards Wood Stairway Replace paragraph 9 3 with the fol lowing A 30 762 mm wide column supported 45 stairway with 8 rise and run of treated Douglas Fir shall be provided at the tower endwall ris ing from grade roof to the fan deck Stair columns shall be nominal 4 x4 Guardrails shall be nominal 2 x4 The upper guardrail shall have an eased edge for the protection of operating personnel Stairway foundation shall be by others designed in accordance with drawings provided by the cooling tower manufacturer The stairway shall conform to OSHA standards E Although they are not necessary for routine operation and main tenance stairways do provide a safe and comfortable means of access to the top of the tower that is often overlooked in the ini tial cooling tower purchase And fiberglass construction provides long term service and stability It also is architecturally compat ible with the basic tower const
4. Marley Sigma F Series Cooling Tower Engineering Data amp Specifications sP COOLING TECHNOLOGIES Marley Sigma F Series Cooling Tower Table of Contents Engineering Data Schematic 4 Support 5 Piping 7 Temperature Control 10 Environmental 11 Specifications Base Base 12 Thermal Performance 13 Construction 14 Fan Deck and Fan Cylinder 15 Mechanical Equipment 15 Fill Louvers and Drift Eliminators 16 Hot Water Distribution System 17 Casing 17 Access and Safety 18 Cold Water Basin 18 Scope of Work 19 Specifications Options Cold Water Basin Options Stainless Steel Cold Water Basin 20 Watertight Partition between Tower Cells 20 Basin Heater 20 Convenience and Safety Options Fiberglass Stairway 21 Wood Stairway 21 Plenum Walkway 22 Ladder Extension 22 Ladder Safety Cage 22 Hot Water Basin Covers 22 Air Inlet Screens 23 Appearance Options Architectural Casing 23 Cased Guardrail 23 Control Options Control System 24 Variable Speed Drive 25 Vibration Limit Switch 26 Miscellaneous Options Galvanized Steel Ladder 26 Fiberglass Ladder 26 Low Noise Tower 27 Fire Retardant Fiberglass 27 Fan Cylinder Extension 27 Increased Wind and or Earthquake Load 27 Premium Hardware 27 Marley Sigma F Series Cooling Tower Tr Sigma F Series is a field erected crossflow fiberglass structure cooling tower designed to serve normal air conditioning and refrigeration systems as well as medium sized industrial load
5. 6 F1240 1500 8650 14 124 12 0 24 0 15 1 3 6 1 774 2 6 E 1250 1500 8650 16 14 12 0 24 0 15 2 3 9 1 77 2 6 F1260 1850 10100 16 14 14 0 28 0 15 234 3 9 FI FE Marley Sigma F Series Cooling Tower Engineering Data Piping Plan 4 G lt TYP SINGLE CELL amp FAN COLUMN AND ANCHOR BOLT D TYP MULTICELL FAN COLUMN AND ANCHOR BOLT RISER AND HEADER m TOWER AND FAN MOTOR PLAN FAN TOWER H ji p G Ge OF A DIA GALVANIZED FLANGE FAN FLANGE IS 3 4 THICK BOLT MOTOR INLET RISER B DIAMETER x CIRCLE CONFORMS TO 125 LB CROSSOVER PIPE 10 7a ANSI SPECIFICATIONS S 7 amp ic it 1 i ov 1 E CONCRETE OOO P a BASIN OPTION T 7 1 BASE OF bese scsoaffeoeeef n TOWER COLUMNS E se Li J STAINLESS STEEL BASIN OPTION END ELEVATION SIDE ELEVATION NOTE 1 Use this bulletin for preliminary layouts only Obtain current drawings from your Marley representative 2 Pumping head contributed by the tower is static lift E 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
6. This warranty shall cover the fan s speed reducer s driveshaft s couplings and the unitized supports Fill Louvers and Drift Eliminators Fill shall be film type 15 mil 0 38 mm 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 splashout Drift eliminators shall be 15 mil 0 38 mm thick PVC formed as part of each fill sheet triple pass cellular type and shall limit drift losses to 0 005 or less of the design water flow rate The final pass of the eliminators shall direct the air toward the fan Specification Value The extended oil line to an oil gauge provides a safe and convenient means of checking the level of oil in the Geareducer Fans of the size used on large cool ing towers are applied at speeds and horsepowers that generate consider able torque and structural tubular steel resists this torque very effectively The Marley torque tube design assures that all of the mechanical equipment remains aligned and that the rotating fan is properly positioned within the fan cylinder Hot dip galvanizing after fabrication assures that all steel surfaces will be heavily coated with zinc for long term protection against corrosion Even i
7. 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 drienby _ hp motor s Pump head including static lift above top of cold water basin curb or top of supporting steel shall not exceed feet of water Tower shall be simi lar and equal in all respects to Marley Sigma F Series Model E 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 accept able 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 Your reason for specifying a crossflow type is that crossflow tow ers are noted for the accessibility and maintainability of all oper ating components The spacious interior provides easy access to fill drift eliminators all basin accessories and is one of two primary accessways to the fan Geareducer and other mechani cal components At the fan deck level the hot water distribution basins are easily inspected and cleaned while the tower is operatin
8. 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 reduc tion 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 signifi cantly e The Marley Variable Frequency Drive automatically mini mizes 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 tempera ture This is a relatively inexpensive solution and can pay for itself quickly in reduced energy costs e 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 7 fan speed or 10 dBA at 4 fan speed e Extreme cases may require inlet and discharge sound attenu ator 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 signifi cant cost impact and because of the obstruction to normal maintenance procedures Your Marley represent
9. in the off posi ion for safety The system shall include a solid state PI temperature controller o adjust frequency output of the drive in response to the tower fluid tempera ure 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 circuit with capability to isolate the VFD when in the bypass mode Transfer to he bypass mode shall be automatic in he event of VFD failure or for specific rip 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 operat ing in bypass to maintain the set point emperature of the cold water The drive design shall be operated as a stand alone system without the need for a BMS sys em Operator controls shall be mounted on the front of the enclosure and shall Marley Sigma F Series Cooling Tower Specifications Options 27 Specification Value consist of start and stop control bypass VFD selector switch Auto Manual selec tor switch manual speed control and solid state temperature controller An emergency bypass selector switch inter nal to the panel allowing the fluid cooler an motor to be run at full speed shall be urnished To prevent heating problems in he fluid cooler fan motor and to assure proper gear box lubrication the VFD sys em shall de energize the mo
10. 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 This option is for those customers who either prefer steel lad ders or whose atmospheric conditions at the cooling tower loca tion would be detrimental to aluminum Marley Sigma F Series Cooling Tower Specifications Options 28 Specifications Specification Value Fiberglass Ladder Change paragraph 9 3 to read as follows One endwall of the tower shall be equipped with an 18 457 mm wide fiberglass vertical ladder supported by hot dip galvanized steel brackets 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 A horizontal swing gravity closing safety bar shall be provided across the ladder opening at the fan deck Low Noise Tower Add the following at the end of para graph 1 1 The cooling tower shall be quiet operating and shall produce an overall level of sound no higher than ____ dBA at the critical location indi cated on the Plans Fire Retardant Fiberglass Add the following paragraph in the Construction section All fiberglass components in the cooling tower shall have a flame spread rating of 25 or less Fan Cylinder Extension Add a third sentence in para
11. 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 tempera ture 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 A CAUTION The cooling tower must be located at such distance and direction to avoid the possibility of contaminated tower 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 tower is in compliance with applicable air pollution fire and clean air codes Marley Sigma F Series Cooling Tower Engineering Data Environmental Sound Control Sound produced by a Sigma tower operating in an unobstructed environment will meet all but the most restrictive noise limita tions 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 sev eral options are available listed below in ascending order of cost Impact e In many cases noise
12. 0 RIZS 6 32 6 24 0 91070 86450 F1261 7 32 6 28 0 102800 98090 OTE Use this bulletin for preliminary layouts only Do not use 4 Last number of model indicates number of cells Change as ap N 1 for construction Obtain current drawings from your Marley representative Operating weight is total wet weight including stainless steel collection basin with 6 recommended operating water level of water Purchaser to design construct and furnish supporting steel complete with 1 6 diameter holes for anchor bolts to suit the general dimensions of current Marley drawings propriate for your selection Primary engineering data is per cell Maintain no less than 2 0 of clear space at tower endwalls for construction purposes Louvered faces must have unobstruct ed air supply If obstructions exist nearby consult your Marley representative Marley Sigma F Series Cooling Tower Engineering Data Support 6 MIN TYF B AIR INLET FACE A SPACES AT 4 0 L OPTIONAL PARTITION WALL FOR INDIVIDUAL CELL OPERATION W IN TO IN OF CURB WALLS CASED ENDWALL FACE CASED ENDWALL FACE SEE NOTE 7 TOP OF BASIN CURB PLAN TOP OF PARTITION WALL To TOP OF BASIN CURB 1 0 1 4 1 6 6 MIN OPERATING WATER LEVEL RECOMMENDED SECTION B SECTION P Tower Dime
13. 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 Motor shall be located outside the fan cylinder at the fan deck and shall be connected to the speed reducer by a tubular stainless steel dynamically bal anced driveshaft with heavy galvanized yokes and neoprene flexible coupling elements III The indicated design values for framing and decking not only give you assurance that the tower can withstand long term operation in a hostile environment but that it will accept many years of inspection and maintenance traffic by your operating personnel Fiberglass reinforced polyester fan cylinders provide the close tip clearances and smooth airflow contour necessary for good fan performance The inert noncorroding nature of FRP assures that these characteristics will persist E Standard fan drives of other manufacturers may use V belts Considering the size of fans involved and the horsepower applied this is not good design practice Geareducer drive is far more reliable and trouble free and is currently offered as an option by most other cooling tower manufacturers The primary means of capacity control on cooling towers is by cycling fans on and off or through a variety of speed changes Such cycling can stretch V belts and can reduce their service life signi
14. PX 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 improvement of this product line Marley Sigma F Series Cooling Tower Engineering Data Schematic 4 4 wW w S 2 S a 2 COLUMN COLUMN COLUMN __ fe REET A BAYS AT 4 0 L 3 TOWER PLAN _ TOP OF FAN CYLINDER B FAN DECK Use this data for preliminary layouts only Obtain current drawing from your Marley sales representative H The UPDATE web based selection software 13 6 available at spxcooling com provides Sigma F Series model recommendations based on customer s specific design requirements BASE OF l TOWER COLUMNS ENDWALL ELAVATION Tower Dimensions Model w L H A B c F1211 29 2 16 0 19 6 4 6 0 144 F1221 31 2 16 0 20 6 4 7 0 168 F1231 31 2 20 0 20 6 5 7 0 168 F1241 31 2 24 0 20 6 6 7 0 168 F1251 35 2 24 0 20 6 6 7 0 216 F1261 35 2 28 0 20 6 y 7 0 216 NOTE 1 Use this bulletin for preliminary layouts only Obtain curren
15. Tower Specifications Options 23 Specification Value Air Inlet Screens Add the following paragraph in the Fill Louvers and Drift Eliminators section The air inlet faces of the tower shall be covered by 1 mesh stainless steel welded wire screens Screens shall be secured to stainless steel frames and shall be removable Appearance Options Architectural Casing Replace paragraph 8 1 with the following Tower endwalls as well as exposed hot water basin sides above the louvered face shall be cased with horizontally installed pultruded fiberglass panels Tower corners shall be finished with pultruded fiberglass angles Cased Guardrail Add the following to the end of this paragraph The casing and cor ner treatment shall extend to the full height of the guardrail described in paragraph 9 2 The additional wind loading imposed by this exposure shall be accounted for in the tower s struc tural design E In wooded or windy areas these screens help to keep leaves or blowing debris out of the cooling tower and circulating water system E This is an architecturally pleasing heavy duty casing that pro vides an appearance similar to shiplap siding See cover photo E Extending the casing to the top of the fan deck guardrail presents a clean architectural appearance by shielding the mechanical equipment and a major portion of the fan cylinder from view It also offers a higher degree of protection for operat
16. able to the owner to compensate for the performance deficiency COLD WATER TEMP F E Your reason for purchasing a cooling tower is to obtain a con tinuing 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 var ies directly with its true thermal capability This paragraph is intended to protect you against either intentional or inadvertent undersizing 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 Your contract with the successful bidder should establish the acceptable remedies for missed performance which might include e 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 e The reimbursement of a portion of the total contract price equal to the percentage deficiency in performance Under no circumstances should you allow the manufacturer to repitch the fans to increas
17. ative 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 Cool ing Tower Performance from your Marley sales representative or on the web at spxcooling com 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 initi ated by the enclosure You ll benefit from discussing your project with your Marley 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 sedimen tary deposits can provide a breeding ground for bacteria In areas prone to
18. described on page 23 io oO N Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Access and Safety Single cell towers shall include a 33 838 mm wide by 61 1 55 m high molded FRP access door in one endwall casing for access to the inte rior of the tower Casing access door shall be hinged and equipped with a latch operable from both inside and outside the tower Multicell towers shall have an access door in both endwalls and shall include a hinged door in each transverse partition to give free access through the tower The top of the tower shall be equipped with a sturdy 42 1067 mm high fiber glass guardrail system complete with top rails intermediate rails and toe boards conforming to OSHA standards Guardrail posts shall be extensions of the tower columns One endwall of the tower shall be equipped with a 20 508 mm wide aluminum vertical ladder supported by hot dip galvanized steel brackets through bolted to the endwall struc ture 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 A horizontal swing gravity closing safety bar shall be pro vided across the ladder opening at the fan deck Cold Water Basin A large galvanized rectangular access door shall be located on both end panels for entry into the cold water basin R
19. 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 To control the buildup of dissolved solids resulting from water evaporation as well as airborne impurities and biological contami nants including Legionella an effective consistent water treatment program is required Simple blowdown may be adequate to control corrosion and scale but biological contamination can only be con trolled with biocides An acceptable water treatment program must be compatible with the variety of materials incorporated in a cooling tower ide ally 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 recom mendations can be found in the Sigma User Manual which accom panies 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 Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Base Furnish and install an induced draft crossflow type field erected structural fiberglass framed PVC film fill industrial duty cooling tower of cell s
20. e Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Hot Water Distribution System The mechanical equipment support crossover pipe for each cell shall be equipped with a flange for the attachment of customer supply piping Inlet and bolt circle dimensions shall conform to 125 flange specifications The crossover pipe shall deliver water through PVC perforat ed pipes to two open stainless steel hot water basins at the fan deck elevation Water shall exit these basins to the fill by gravity through metering orifice type poly propylene nozzles situated in the basin floor Nozzles shall be easily removable and replaceable Water inlet system shall be self balancing requiring no special valving for flow regulation from side to side of tower Water distribution system design shall allow water flow reductions down to 50 of design flow without modifica tions or adjustments Casing The endwalls of the tower as well as the sidewalls above the air inlet elevation to the top of the distribution basin shall be cased with 12 oz sq ft horizontally corrugated FRP panels attached to tower columns with stain less steel self tapping fasteners and self sealing washers Panels shall be lapped to shed water inward to the tower Vertical joints shall be lapped and sealed watertight Casing ends at tower corners shall be covered with pultruded FRP angles In the waterwashed endwal
21. e 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 45 F RANGE 75 lt gt 10 F RANGE A 15 F RANGE 70 65 60 55 50 55 60 65 70 75 80 WET BULB TEMP F Typical cooling tower performance curve Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Construction The tower shall be capable of with standing water having a pH of 6 5 to 8 0 a chloride content NaCl up to 750 ppm a sulfate content S04 up to 1200 ppm a calcium content CaCO3 up to 800 ppm silica SIO2 up to 150 ppm and design hot water tempera tures up to 120 F 48 9 C The circulat ing water will contain no oil grease fatty acids or organic solvents The structural framework of the tower shall be pultruded or molded fiberglass designed in accordance with ASCE Structural Plastics Design Manual All allowable design values shall be factored for wet service temperature and duration in accordance with standard engineering practices Basic design criteria shall be 30 psf 1 44 kPa wind load and 5 g seismic load Multicell towers shall include stainless steel partitions between cells in the fill areas and fiberglass partitions in the plenum area Partitions shall extend the full height
22. ectangular panels are shall be provided for access to the fan plenum area to facilitate inspection and allow maintenance to the fan drive system Concrete partitions if required between cells in the cold water basin shall be installed in accordance with manufacturer s drawings Tower installer shall seal between tower cell partitions and basin cell partitions E The access doors on other towers may be unreasonably small Specifying the size of the door will cause those bidders to take exception 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 struc tural integrity of the fan deck fan cylinder and fan especially the fan blade securing hardware And there are no induced draft cooling tower designs that are immune to this need Please beware of those manufacturers who suggest otherwise For the comfort and safety of your operating personnel the Sigma F Series 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 E 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 stainless steel cold wat
23. er collection basin indicated on page 20 should be included in the specifications Marley Sigma F Series Cooling Tower Specifications Base Specification Value Scope of Work The cooling tower manufacturer shall be responsible for the design fabrica tion and delivery of materials to the project site and for the erection of the tower over supports provided by others Unless otherwise specified all supply and return piping pumps con trols and electrical wiring will be out side the cooling tower manufacturer s scope of work E 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 the execution and imple mentation of the contract N amp Marley Sigma F Series Cooling Tower Specifications Options 20 Specifications Specification Value Cold Water Basin Options Stainless Steel Cold Water Basin Replace paragraph 10 1 with the following Include a cold water col lection basin constructed of 12 gauge series 304 stainless steel through bolted and sealed to prevent leakage A depressed side outlet sump of series 304 stainless steel having a 1 4 6 4 mm thick faceplate drilled for a standard class 125 ASME flange con nection will be included A removable
24. ficantly Unless otherwise specified motor speed will be 1800 RPM in 60 Hertz areas and 1500 RPM in 50 Hertz areas If you prefer the operating flexibility of two speed operation please specify the RPM to be 1800 900 1500 750 in 50 Hertz regions Other speed ranges are also available The driveshaft turns at the motor speed and is therefore most sensitive to operational imbalance Stainless steel manufacture assures that the driveshaft will not become unbalanced as a result of corrosion Stainless steel yokes are available at extra cost although not normally necessary Marley Sigma F Series Cooling Tower Specifications Base Specifications A stainless steel oil fill and drain line shall extend from the gear reducer to the vicinity of the motor and shall be equipped with a bronze bodied oil level sight glass gauge The complete mechanical equipment assembly for each cell shall be sup ported 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 hot dip 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 The mechanical equipment assembly shall be warranted for no less than five 5 years
25. forms or foundations This is the simplest of several cold water basin designs available for the Sigma F Series towers If preferred a 10 gauge welded stainless steel basin can be installed E In addition to the normal partition function of preventing air bypass page 14 this option allows you to use each partitioned cell of your tower independently This is valuable where a single multicell tower is serving several separate systems or where winter operation may require less than full tower capability E The basin heater components described at left represent is rec ommended for a reliable automatic system for the prevention of basin freezing The ambient air temperature that you fill in should be the lowest 1 level of winter temperature prevalent at site Marley Sigma F Series Cooling Tower Specifications Options 21 Specifications Specification Value and a solid state circuit board for tem perature control and low water cutoff A control probe shall be located in the basin to monitor water level and tem perature The system shall be capable of maintaining 40 F water temperature at an ambient air temperature of _ _ F Wiring of the heaters and the heat er components shall be the responsibil ity of the purchaser Convenience and Safety Options Fiberglass Stairway Replace paragraph 9 3 with the following One endwall of the tower shall be equipped with a structural fiberglass stairway rising from grade
26. g if neces sary 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 particularly of forced draft configuration can make difficult work for maintenance personnel Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Thermal Performance The tower shall be capable of cooling GPM of water from ___ F to F at a design entering air wet bulb temperature of F The cool ing tower manufacturer shall guarantee that the tower supplied will meet the specified performance conditions when the tower is installed according to plans 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 disinter ested third party in accordance with CTI Cooling Technologies Institute ATC 105 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 agree
27. graph 4 2 to read as follows Overall fan cyl inder height shall be 10 feet above the fan deck level Increased Wind and or Earthquake Load Premium Hardware E This option is for those customers who either prefer fiberglass ladders or whose atmospheric conditions at the cooling tower location dictate its use E Sound produced by a Sigma tower operating in an unobstructed environment will meet all but the most restrictive noise limita tions Where sound levels may be considered critical however low noise levels can be achieved by any of several techniques Please discuss your requirements with your local Marley sales representative E This option will affect the the standard casing panels the plenum partitions between cells the fan cylinders and the optional fiber glass stairway flights and landing panels E Extended fan cylinder heights are useful where it is important to discharge the cooling tower s leaving plume at a certain eleva tion This may be to avoid recirculation or to keep the plume above a nearby structure E If your geographic location dictates the application of higher wind and or seismic loads please discuss with your local Marley repre sentative and change paragraph 3 3 to read appropriately Please also ask for revised concrete basin or supporting steel drawings from Marley which reflect the higher load requirements E Marley can provide hardware materials suitable for all aggres sive water condi
28. ion and main tenance personnel Marley Sigma F Series Cooling Tower Specifications Options 24 Specification Value Control Options Control System Add the following paragraphs in the Mechanical Equipment sec tion 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 control ling single speed or two speed motors as required and designed specifically for cooling tower applications The panel shall include a main fused dis connect with an external operating handle lockable in the off position for safety Across the line magnetic start ers or solid state soft start starters as required shall be controlled with a thermostatic or solid state tempera ture 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 tem perature sensing bulb installed in the cold water basin using a suspension mounting bracket If a solid state tem perature controller is used the control ler will be door mou
29. istribution System section The distribution basins shall include stainless steel covers These covers shall be designed to withstand 40 psf 1 92 kPa live load and shall be easily removable for maintenance EThis option permits freedom of movement for inspection or main tenance 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 sump screens probes basin heaters etc The need for guardrails where basins are deeper than 4 0 1 22 m is an OSHA requirement E Many towers are installed such that the base of the tower is 2 0 610 mm 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 s ladder extensions are available in standard 5 0 1 52 m and 11 0 3 35 m lengths and will be field cut to fit E To meet OSHA standards towers whose fan decks are 20 0 6 10 m or more above roof or grade and which are equipped with ladders are required to have safety cages surrounding the ladders Their use on lower elevation towers is a matter of choice E These covers are designed to keep leaves and debris out of the circulating water system They also serve to suppress algae for mation by shielding the incoming hot water from direct sunlight Marley Sigma F Series Cooling
30. l fill areas inner casings of 16 gauge 304 stain less steel shall also be provided E Gravity flow distribution basins are a feature of crossflow type towers These basins are out where they can be easily inspect ed even cleaned while the tower is in operation Spray sys tems of counterflow towers being sandwiched between the top of the fill and the drift eliminators are extremely awkward to access and maintain and require the system to be shut down for cleaning The Sigma F Series is designed such that the supply piping to the tower will not appear outside the tower Not only does this enhance the tower s architectural appearance but it also aids the self balancing aspect of the Sigma F Series water distribution system This feature of the Sigma F Series tower allows you to vary the water circulation rate as an added means of controlling tower per formance capacity during reduced load or off season operation IB 8 oz casing panels are also available at reduced cost but the stur dier 12 oz panels are strongly recommended Also if fire retardant casing is preferred it would be appropriate to add the following sentence to the end of paragraph 8 1 at left Casing panels shall have a flame spread rating of 25 or less Heavy duty architectural casing panels are also available as described on page 23 Architectural treatment can also be enhanced by extending the casing up to the top of the fan deck guardrail This is
31. n aggressive water conditions the heavy construction of the unitized support normally precludes the need for stainless steel It is available however at extra cost 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 Marley Cooling tower vendors who purchase commercial fans gear boxes driveshafts etc may require that you deal directly with those commercial suppliers for warranty satisfaction E Louvers integral with the fill keep the flowing water within the confines of the fill The separate external louvers used by oth ers 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 lou vers will put your operating concerns to rest 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 with out premium cost If a lower rate is required please discuss with your Marley sales representativ
32. nsions Operating Weight Ib Model Note 4 A w L Single Fan Cell Each Cell Add FIZ 4 26 4 16 0 39220 35920 E1221 4 28 4 16 0 41460 38160 F1231 5 28 4 20 0 48200 44860 F1241 6 28 4 24 0 55300 51980 F1251 6 32 4 24 0 61260 57880 F1261 7 32 4 28 0 68280 64800 NOTE 1 Use this bulletin for preliminary layouts only Do not use 5 All anchor bolts complete with nut and washer will be furnished for construction Obtain current drawings from your Marley representative 2 Tower weight is total wet operating weight of tower only ex cluding water in the concrete basin 3 Purchaser to design construct and furnish concrete basin complete to suit the general dimensions of current Marley drawings 4 Last number of model indicates number of cells Change as ap propriate for your selection Primary engineering data is per cell by others Bolts are diameter with 114 all thread projection Material should be stainless steel Maintain no less than 2 0 of clear space at tower endwalls for construction purposes Louvered faces must have unobstruct ed air supply If obstructions exist nearby consult your Marley representative Purchaser must design construct and furnish sump s and overflow s to suit requirements The sump should be designed according to the pump manufacturer s recommendations Marley Sigma F Series Cooling Tower Engineering Data Piping Plan 2
33. nted 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 tempera ture controller in the control panel E 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 F Series Cooling Tower Specifications Options 25 Specifications Specification Value Fan Motor Variable Speed Drive Marley All Weather ACH550 System 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 pro vided The VFD shall use PWM technol ogy 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 exte
34. of the tower from the base of fill to the underneath side of the fan deck Column lines shall be on no greater than 4 0 1 22 m longitudinal centers and the base of all columns shall be firmly anchored to series 304 stainless steel base plates Framing joints shall be made with 1 2 diameter or larger series 300 stainless steel machine bolts Critical framing joints shall be augmented with 1 06 OD heavy wall fiberglass sleeves to transmit loads No field gluing of joints or any other structural member will be allowed E The 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 please change hardware material requirement to series 316 stainless steel or silicon bronze as you may have agreed upon beforehand with the Marley sales representative If there is any doubt in your mind as to the grade of hardware that is appropriate to your water quality please have a sample of it analyzed and provide Marley with a copy of the analysis Discuss higher design loadings with your Marley sales represen tative Multicell towers must have plenum partitions between cells Otherwise 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 unsat isfactory Fill partitions prevent the random migra
35. our can overheat the mo tor 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 increas ing 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 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 10 Variable Speed Fan Frequency modulation devices work well on induced draft propeller fan cooling towers such as the Sigma 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 abso lute temperature control
36. recommended location is through the tower endwall into the plenum area Review of the system by SPX engineering is required 4 All header and riser piping to be furnished by others A corrosion resistant material or coating for piping is recommended Do not support riser dead load or operating load from inlet connection or tower structure Marley Sigma F Series 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 tempera ture 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 Techni cal Report H 001A available from your Marley sales represen tative 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 Vary ing 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 tempera tures within an acceptable range However exceeding a total acceleration time of 30 seconds per h
37. rnal 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 temperature and cold fluid temperature on two separate lines The bypass shall include a complete magnetic bypass circuit and with capabil ity 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 tempera tures while the VFD is in a by pass mode Operator controls shall be mounted on the front of the enclosure and shall con sist 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 lubrica tion the VFD system shall de energize the motor once 25 motor speed is reached nimb
38. ruction and appearance E Where atmospheric conditions at the jobsite are not aggressive the treated wood stairway may be chosen because of its lower cost Marley Sigma F Series Cooling Tower Specifications Options 22 Specifications Specification Value Plenum Walkway Add the following to the end of this paragraph Provide a 30 762 mm minimum wide walkway extending from one endwall access door to the other through the length of the tower Walkway shall be constructed of fiberglass components with a nonskid surface on floor members and the top of the walkway shall be above the cold water basin overflow level If the cold water basin is deeper than 4 0 1 22 m the walkway shall be equipped with fiberglass guardrails Ladder Extension 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 Add the following to the end of this paragraph A heavy gauge galvanized steel safety cage shall surround the ladder extending from a point approxi mately 7 0 2 13 m above the base of the ladder to the top of the guardrail surrounding the fan deck Hot Water Basin Covers Add the following paragraph in the Hot Water D
39. s Evolving from the crossflow concept of cooling tower pioneered by Marley in 1938 and incorporating over 65 years of design advancements the Sigma F Series 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 F Series 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 12 through 27 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 lI Pages 12 through 19 indicate those paragraphs which will result in the purchase of a cooling tower which will not 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 through 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 F Series S
40. side of tower plan area must be supported by others Tower Flow Cell Dimensions Model GPM A z z z F1210 1050 5750 Z 10 8 0 16 0 15 1074 T F1220 1050 5750 14 12 8 0 16 0 BA 8 6 F1230 1320 7200 14 12 10 0 20 0 EA 8 6 F1240 1500 8650 14 12 12 0 24 0 15 1174 86 F1250 1500 8650 16 14 12 0 24 0 16 07 10 6 F1260 1850 10100 16 14 14 0 28 0 16 0 10 6 Marley Sigma F Series Cooling Tower Engineering Data Piping Plan 3 C TYP SINGLE CELL FAN H COLUMN AND ANCHOR BOLT RISER D TYP MULTICELL FAN TOWER F INLET RISER MOTOR PLAN B DIAMETER CROSSOVER PIPE k le ho a 26 x 26 INTERNAL RISER SLEEVE AIR SEAL SS BASIN FAN COLUMN AND ANCHOR BOLT RISER rot TOWER AND FAN H dere OF A DIA GALVANIZED FLANGE FAN FLANGE IS 3 4 THICK BOLT CIRCLE CONFORMS TO 125 LB 10 1 8 ANSI SPECIFICATIONS f E CONCRETE BASIN OPTION i BASE OF TOWER COLUMNS mas ea CUAD ASIN END ELEVATION SIDE ELEVATION Tower Flow Cell Dimensions Model GPM A B c D E F G H F1210 1050 5750 12 10 8 0 16 0 15 0 a ere 2 6 F1220 1050 5750 14 125 8 0 16 0 15 1 3 6 1 77 2 6 F1230 1320 7200 14 124 10 0 20 0 15 1 3 6 2 77 3
41. stainless steel 1 2 mesh debris screen shall cover the top of the sump An appropriately sized 4 diameter or larg er stainless steel 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 Watertight Partition between Tower Cells with Stainless Steel Cold Water Basin Option Replace paragraph 10 2 with the following Stainless steel watertight partitions shall be provided between cells in the cold water basin They shall be sealed watertight to the partitions in the fill and plenum areas of the tower Cold water basin partitions shall have weir openings allowing free flow of water between cells Weirs shall be equipped with bolt on gasketed cover plates to prevent water passage when required Basin Heater Add the following paragraph in the Cold Water Basin section Add the following paragraph in the Cold Water Basin section Provide a system of electric immersion heaters and con trols 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 A NEMA 4 enclo sure shall house a magnetic contactor to energize heaters a transformer to provide 24 volt control circuit power E Marley basins are used to permit the installation of towers on elevated plat
42. t drawings from your Marley representative 2 All table data is per cell 3 All tower installations require a minimum of 4 0 from cen terline of tower endwall column to any vertical obstruction at tower ladder location Ladder can be located at any corner of the fan deck Ladder extends 8 below the base of tower columns on applications with a stainless steel cold water basin Ladder stops at top of basin curb wall on applications with a concrete basin Tower installations with an elevation 20 0 or more from the top of the fan deck to grade or roof level require a safety cage on the tower ladder in compliance with OSHA standards Marley ladder safety cages are available as an option Marley Sigma F Series Cooling Tower Engineering Data Support A SPACES AT 4 0 L AIR INLET FACE r INTERMEDIATE BEAM I a i a 9 z 2 MAKEUP KA SUMP VALVE iL i S i s E Z re E aff OoOO ee ee U e OVERFLOW a a 3 al S AIR INLET FACE PRIMARY SUPPORT COL amp ANCH BOLT PLAN PRAN ava MAX i NORMAL j GAGE Ts T T T T SECTION ELEVATION Tower Dimensions Operating Weight Ib Model s Note 4 A w Single Fan Cell Each Cell Add FZ tl 4 26 6 16 0 55810 51510 221 4 28 6 16 0 59300 54920 F1231 5 28 6 20 0 70180 65760 F1241 6 28 6 24 0 81410 7702
43. tion of water from cell to cell and permit individual cell operation during reduced ambient or low load conditions The variable weather conditions encountered during on site construction of cooling towers does not result in the stable condi tions of temperature and humidity that assure proper bonding during the gluing process Marley Sigma F Series Cooling Tower Specifications Base Specifications Specification Value Fan Deck and Fan Cylinder The fan deck shall act as a working platform for maintenance personnel It shall consist of 1 1 8 28 5 mm deep pultruded fiberglass interlocking pan els supported by structural fiberglass joists on 3 0 914 mm maximum centers Fan deck shall have a nonskid surface Deck shall be designed for a uniform live load of 60 psf 2 9 kPa or a concentrated load of 400 pounds 181 kg Mid span deflection at 60 psf 2 9 kPa loading shall not exceed 0 17 4 3 mm Fan cylinders shall be molded FRP They shall be anchored to the fan deck structure to provide a consistently stable operating shroud for the fan Mechanical Equipment Fan s shall be propellertype incor porating heavy duty blades of high strength inert fiberglass reinforced epoxy material Blades shall be indi vidually adjustable and replaceable Fan s shall be driven through a right angle industrial duty oil lubricated geared speed reducer Speed reducers employing pulleys and belts will not be accepted
44. tions including salt water Please discuss with your Marley representative and change specification paragraphs appropriately SP COOLING TECHNOLOGIES 7401 WEST 129 STREET OVERLAND PARK KANSAS 66213 UNITED STATES 913 664 7400 spxcooling ct spx com spxcooling com In the interest of technological progress all products are subject to design and or material change without notice 2010 SPX Cooling Technologies Inc Printed in USA FSIG TS 10
45. tor once 25 motor speed is reached and cool ing 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 Add the following paragraph in the Mechanical Equipment Section A single pole double throw vibration limit switch ina 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 vibra tion It shall be adjustable for sensitiv ity and shall require manual reset Miscellaneous Options Galvanized Steel Ladder Change paragraph 9 3 to read as fol lows One endwall of the tower shall be equipped with an 18 457 mm wide hot dip galvanized steel vertical ladder supported by hot dip galva nized steel brackets 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 A horizontal swing gravity closing safety bar shall be provided across the ladder opening at the fan deck E Unless
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