SPX Cooling Technologies Marley Sigma Steel User's Manual
Contents
1. B DIA FLOW FACE OF A DIA CONTROL VALVE INLET FLANGE k MARLEY PIPING STOPS HERE ae he C G COF FLANGE TO BASE OF TOWER COLUMNS lee FOR STATIC LIFT Tower GPM Dimensions Model per cell A B c D E F G 500 3800 10 Cu 8 10 2 14 6 4 121 111 6 0 12 0 Ce E 3801 4500 12 10 9 0 14 73 4 122 111 650 6000 14 10 8 0 16 0 10 0 14 1 14 73 4 123 111 650 6000 14 104 8 0 16 0 11 02 15 1 4 14 73 4 1000 6000 14 10 11 0 14 734 124 111 10 0 20 0 Se ioa S 6001 7500 16 2 11 1 14 85 125 111 1000 7500 16 12 10 0 20 0 BETA 17 1 4 14 834 126 111 1000 9000 161 12 12 0 24 0 13 12 17 1 4 14 834 127 111 1500 10500 18 14 14 0 28 0 13 5 17 1 14 93 4 NOTE 1 Use this bulletin for preliminary layouts only Obtain 4 Marley piping terminates at face of a cast iron flat face current drawings from your Marley sales representative flange Bolt circle conforms to class 125 Ib ANSI B 16 1 2 Pumping head contributed by the tower is static lift specifications G Actual pumping head will vary according to tower 5 Supports on tower for crossover piping are part of the circulating GPM Total pumping head will be furnished at tower design Do not support the riser s dead load or time of propos2. 14 4 7 0 168 75 17 4 124 111 1000 7500 29 4 20 0 20 1 5 7 0 168 75 17 4 125 111 1000 7500 33 4 20 0 20 1 5 7 0 216 75 yoy 126 111 1000 9000 33 4 24 0 20 1 6 7 0 216 100 175 127 111 1500 10500 33 4 28 0 20 1 y 7 0 216 100 17 6 NOTE 1 Use this bulletin for preliminary layouts only Obtain cur 3 Height shown is from base of tower columns to top of fan rent drawings from your Marley sales representative cylinder 2 Last number of model indicates number of cells Change as 4 Pumping head shown is from base of tower columns appropriate for your selection Primary engineering data is per cell Marley Sigma Steel Cooling Tower Engineering Data Support F 7 E A SPACES AT 4 0 L AIR INLET FACE z o a a lt x S amp 3 zoo gt RECOMMENDED iM D OPERATING WATER LEVEL S 5 1 6 w 6 i O zZ WU O Section S A AIR INLET FACE INTERMEDIATE PRIMARY SUPPORT BEAM BEAM Plan TEGN Dimensions Operating Weight Ib Modei 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 Use this bulletin for preliminary layouts only Obtain cur 3 Maintain at least 2
3. Construction section The tower shall include all design and material modi fications 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 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 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 E 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 E 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 E This could have a very beneficial effect upon your fire insurance premiums Towers not able to meet FM require ments may
4. Marley Sigma Steel Cooling Tower Engineering Data amp Specifications SP COOLING TECHNOLOGIES Marley Sigma Steel Cooling Tower Table of Contents Engineering Data Schematic 6 Support 7 Concrete Basin 8 Piping 9 Environmental 10 Energy Management 11 Specifications Base Base 12 Thermal Performance 13 Construction 14 Fan Deck and Fan Cylinder 15 Mechanical Equipment 15 Fill Louvers and Drift Eliminators 17 Hot Water Distribution System 18 Casing 18 Access 18 Cold Water Collection Basin 19 Scope of Work 19 Specifications Options Control Options Control System 20 Basin Heater 21 Fan Motor Variable Speed Drive 21 Marley Premium VFD System 22 Vibration Limit Switch 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 25 Factory Mutual Approval 25 Hot Water Basin Covers 25 Air Inlet Screens 25 Low Noise Tower 26 Service Life Relate Customization 27 Marley Sigma Steel Cooling Tower he Sigma Steel is a galvanized steel field erected general purpose crossflow cooling tower designed to serve normal air conditioning and refrigeration sys tems as well as medium sized industrial loads Evolv ing from the crossflow concept of towers pioneered by Marley in 1938 and incorporatin
5. on the front of the enclosure and shall consist of start and stop control bypass VFD selector switch Auto Manual selec or 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 motor 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 lce 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 E Unless specified otherwise a Metrix switch will be provided A double pole double throw Add the following paragraph in the model is also available If purchased in con Mechanical Equipment section A junction with the Control System it is also single pole double throw vibration limit factory wired The requirement for manual switch in a NEMA 4 housing shall be reset assures that the tower will be visited to installed on the mechanical equipment determine the cause of excess vibration support for wiring into the o
6. 0 of clear space at tower endwalls for rent drawings from your Marley sales representative construction purposes Air inlet faces must have unobstructed 2 Steel beams must include 7 dia holes to accept anchor bolts air supply If obstructions exist nearby consult your Marley provided with tower Other contractors or purchaser must sales representative design and erect supporting steel 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 6 MIN gt W INTO IN OF BASIN 6 MIN MIN gt 5 CASED ENDWALL FACE 4 el 3 B z WA z ANCHOR BOLTS hi F SEE NOTE 5 w T suma m __ rs b m eres z z im S O K ba lt CASED ENDWALL FACE 6 MIN 5 Plan RECOMMENDED OPERATING WATER LEVEL 4 LS Section Tower Dimensions Operating Weight Ib Model A Ww 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 4 Minimum basin depth is 1 6 Basin depth may vary to
7. a hinged access door shall be provided in each partition for freedom of access throughout the tower E The limiting water quality values indicated are those which are accept able 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 E Hot 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 E 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 opera tion of the tower would be completely unsatisfactory Marley Sigma Steel Cooling Tower Specifications Base 15 Specification Value Fan Deck and Fan Cylinder 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 Fan cylinders shall be molded FRP They shall be through bolted to the fan deck structure to provide a consistent ly stable operating shroud for the fan Mechanical Equipment Fan s shall be propellertype incorpo rating heavy duty blades of cast alumi num or high strength inert composite material Blades shall be i
8. basin to facilitate cleaning Air inlet faces of the tower shall be free of water splash out Drift eliminators shall be PVC triple pass and shall limit drift losses to 0 005 or less of the design water flow rate Louver Section Fill Section 17 Specification Value E 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 particu larly for free cooling integral louvers will put your operating concerns to rest E Vertical blade type eliminators as well as misdirected cellular types cause dy 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 a performance Drift rate varies with design water loading and air rate as well as drift eliminator depth and number of direc tional 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 represen tative Drift Eliminator Section Marley Sigma Steel Cooling Tower Specifications Base Hot Water Distribution System The mechanical equipment support crossover pipe shall deliver wat
9. 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 Perfor mance from your Marley sales representative or on the web at spxcooling com 10 As suggested in the aforementioned Technical Report it may also be advisable to specify a design wet bulb tem perature 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 Atmo spheric 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 con sider 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 miti
10. adder 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 E 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 25 Specifications Specification Value Oil Level Sight Glass Replace paragraph 5 4 with the fol lowing 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 bronze bodied oil level sight glass Miscellaneous Options Steel Cold Water Basin Replace paragraph 10 1 with the fol lowing 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 connec tion 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 make up valve shall also be included installed adjacent to the endwall access door Factory Mutual Approval Add the following paragraph in the
11. ained while the tower is in operation Spray systems of counterflow towers sand wiched between the top of the fill and the drift eliminators are extremely awkward to access and maintain E 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 E Steel inner casings provide lateral sup port for the fill that FRP panels cannot They also support the FRP casing pan els against the high wind loads that will act on the tower during its lifetime E The access doors on other towers may be unreasonably small Specifying the size of the door will cause those bidders to take excep io a io Marley Sigma Steel Cooling Tower Specifications Base Specifications The top of the tower shall be equipped with a sturdy 42 high guardrail sys tem complete with top rails interme diate 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 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 d
12. al operating load from the tower Do not brace the riser s 3 If your application requires a bypass system seismic or thrust loads against the tower recommended location is through tower endwall into 6 Butterfly valves or piping expansion joints if used are plenum area Review of the system by SPX engineering is by others and must be located outside the limits of the required cooling tower F 7 Motor must be located 180 from inlet Marley Sigma Steel Cooling Tower Engineering Data Environmental Sound Control Sound produced by a Sigma Steel tower operating in an un obstructed environment will meet all but the most restrictive noise limitations and will react favorably to natural attenu ation 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 e 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 situa tions 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
13. all catch a fan spinning in the reverse direction without tripping The panel shall include a main discon nect 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 manage ment system the drive must have the capability to receive a 4 20 ma tempera ture 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 dis play shall be able to display the set point ML E The basin heater components described at left represent our recom mendation 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 E Marley VFD drive systems are designed to combine absolute tempera ture 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 com ponents The improved energy management provides fast payback Indeed many utiliti
14. atible with it than the designer and manufacturer of the cooling tower N Marley Sigma Steel Cooling Tower Specifications Options 21 Specifications Specification Value Basin Heaters 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 shut down The system shall consist of one or more stainless steel electric immer sion heaters installed in the basin A NEMA 4 enclosure shall house a mag netic 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 tem perature at an ambient air temperature of _ F 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 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 sh
15. ators 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 Your Marley representative can help you meet your sound require ments Marley Sigma Steel Cooling Tower Specifications Options 27 Specification Value Service Life Related Customization E Some adverse water conditions unsatisfactory air quality and or pro cesses 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 rep resentative and extract from it those paragraphs that make sense for you SP COOLING TECHNOLOGIES 7401 WEST 129 STREET OVERLAND PARK KANSAS 66213 UNITED STATES 913 664 7400 spxcooling spx com 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 SSIG TS 08A
16. eason 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 Your contract with the successful bidder should establish the accept able remedies for missed performance which might include eThe 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 start ers piping etc eThe 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 re pitch the fans to increase motor brake horsepower above that shown in the proposal That creates additional operating costs that wil
17. eck guardrail and shall be designed and installed in confor mance with OSHA standards Cold Water Collection Basin The collection basin shall be heavy gauge 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 fac tory installed float operated mechani cal 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 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 external piping pumps controls and electrical wiring will be outside the cooling tower manufacturer s scope of work 19 Specification Value tion alerting you to a potential maintenance head ache E Good maintenance practice requires period ic 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 secur ing hardware There are no induced draft cooling tower designs that are immune to this need E For the comfort and sa
18. equiring routine maintenance is as easily accessed The confined areas that typify counterflow designs can make difficult work for maintenance personnel we 2 Marley Sigma Steel Cooling Tower Specifications Base 13 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 Technology Institute ATC 105 standards during the first full year of operation If the tower fails to per form 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 per form as specified then the manufac turer shall make such reimbursements as are appropriate and agreeable to the owner to compensate for the perfor mance deficiency E Your r
19. er 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 polypro pylene nozzles situated in the basin floor Nozzles shall be easily removable and replaceable Heavy duty industrial grade flow control 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 stain less steel operating stems and heavy duty locking handles Casing 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 In the waterwashed fill areas inner casings of 16 gauge galvanized steel shall also be provided Access 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 1 gt 18 Specification Value E Gravity flow distribution basins are a feature of crossflow type towers These basins are out where they can be easily inspected even maint
20. es offer generous rebates for users having installed VFD drives Marley Sigma Steel Cooling Tower Specifications Options m Specification Value emperature 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 o the bypass mode shall be manual in he event of VFD failure Once the motor is transferred to the by pass circuit the an 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 manu facturer shall supply VFD start up assis tance Tower vibration testing throughout the speed range is required to identify and lockout any natural frequency vibra tion levels which may exceed CTI guide lines Marley Premium VFD System Add the following paragraph in the Mechanical Equipment section when VFD is used as a stand alone system A co
21. fety 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 bid ders Portable ladders and other make do access means are inappro priate 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 steel cold water collection basin indi cated on page 24 should be included in the specifications 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 Marley Sigma Steel Cooling Tower Specifications Options 20 Specification Value Control Options Control System 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 8R or 4X outdoor enclosure capable of controlling single speed or two speed motors as required and designed specifi cally 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 start ers or solid state soft start
22. g 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 tow er 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 only accomplish the specified thermal performance but which will include normal operation and mainte nance 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 require ments Space does not permit definition and explanation of all of the possible options that can be applied to the Sigma Steel SPX Cooling Technologie
23. gating the potential of corrosion and scale but biological contamination can only be controlled with biocides An acceptable water treatment program must be compat ible 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 dam age 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 A 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 i 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 Unles
24. hall be equipped with 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 above the base of the ladder to the top of the guardrail sur rounding the fan deck E Although they are not necessary for routine operation and mainte nance 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 configura tions to accommodate your site requirements E This option permits freedom of movement for inspection or mainte nance within the tower without the need for wading boots or tower drainage It also helps prevent maintenance personnel from damag ing submerged accessories in the cold water basin such as screens probes basin heaters etc E 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 l
25. 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 E 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 flex ibility of two speed operation please specify the RPM to be 1800 900 1500 750 in 50 Hertz regions Marley Sigma Steel Cooling Tower Specifications Base 16 Specification Value 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 neo prene flexible coupling elements 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 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 eq
26. l continue for the life of the tower and imposes no penalty on the manufacturer 95 90 Hi 5 F RANGE 75 lt gt 10 F RANGE Aa 15 F RANGE 70 COLD WATER TEMP F 65 60 50 55 60 65 70 75 80 WET BULB TEMP F Typical cooling tower performance curve Marley Sigma Steel Cooling Tower Specifications Base 14 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 300 ppm a sulfate content S04 up to 250 ppm a calcium content CaCO3 up to 500 ppm silica SiO2 up to 150 ppm and design hot water tem peratures up to 120 F The circulating water shall contain no oil grease fatty acids or organic solvents 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 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 diameter and larger Series 300 stainless steel machine bolts nuts and washers Towers of more than one cell shall include galvanized internal partitions to separate the fan plenums and
27. 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 e In many cases noise concerns are limited to nighttime when ambi ent 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 e Variable speed drives automatically minimize the tower s noise level during periods of reduced load and or reduced ambient without sacri ficing 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 continu ously 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 Extreme cases may require inlet and discharge sound attenuator sections however the static pressure loss imposed by attenu
28. mplete 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 posi tion 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 tempera ture 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 Marley Sigma Steel Cooling Tower Specifications Options i Specification Value 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
29. ndividually adjustable and replaceable Fan s shall be driven through a rightangle indus trial duty oil lubricated geared speed reducer Speed reducers employing pulleys and belts will not be accepted 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 E 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 E Fiberglass reinforced polyester fan cylinders provide the close tip clear ances 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 E Propeller type fans require only half the operating HP of blower type fans They should be readily adjustable to permit compensation for job site conditions that may tend to overload the motor The fans of one manu facturer 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
30. oling 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 E Your specification base establishes the type configuration base mate rial 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 allot ment and whose power usage is acceptable Limitations on physical size and total operating horsepower avoid the introduction of unfore seen 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 r
31. require the inclusion of a fire protection sprinkler system to achieve a comparable level of insurance premium APPROVED cost E These covers are designed to keep leaves and debris out of the circu lating water system They also serve to suppress algae formation by shielding the incoming hot water from direct sunlight E In wooded or windy areas these screens help to keep leaves or blow ing debris out of the cooling tower and circulating water system Marley Sigma Steel Cooling Tower Specifications Options 26 Specifications Specification Value Low Noise Tower 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 E 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 eWhere only a slight reduction in noise will satisfy and the source of concern is in a particular direction
32. s 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 better ment of this Marley product line Marley Sigma Steel Cooling Tower Engineering Data Schematic 6 x lu e w Sa rd N COLUMN COLUMN COLUMN on fe C DIAMETER FAN A BAYS AT 4 0 L 41 2 TOP OF FAN CYLINDER FAN DECK Use this data for preliminary layouts only B Obtain current drawing from your Marley sales representative er ae H The UPDATE web based selection software available at spxcooling com provides 13 11 8 Sigma Steel model recommendations based on customer s specific design requirements TOWER CouMNs Tower GPM Dimensions Maximum ae Model per cell w L H A B c Motor hp Head 121 111 500 4500 25 4 12 0 19 11 4 3 6 0 120 60 ny 122 111 650 6000 27 4 16 0 19 14 4 6 0 144 60 17 4 123 111 650 6000 29 4 16 0 20
33. s your system will benefit from the coldest possible water tempera ture you should consider controlling cold water tempera tures 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 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 tem peratures 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 increas ing the number of potential operating modes Users in north ern climates will find that the tower can carry winter loads at half speed reducing fan power requirements by 85 during
34. 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 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 tempera ture controller in the control panel the execution and implementation of the contract 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 whole hearted agreement with you Who better to determine the most efficient mode and manner of a tower s operation and to apply a system most comp
35. suit use for construction Obtain current drawings from your your storage requirements Marley sales representative Concrete basin design and 5 All anchor bolts complete with nut and washer must be construction are by other contractors or purchaser furnished by others Bolts must be diameter with 114 2 Operating weight is total wet operating weight of tower all thread projection only excluding water in concrete basin 6 Other contractors or purchaser must design locate 3 Maintain at least 2 0 of clear space at tower endwalls construct and furnish sump s and overflow s to suit or construction purposes Air inlet faces must have requirements The sump s should be designed according unobstructed air supply If obstructions exist nearby to the pump manufacturer s recommendations Other consult your Marley sales representative 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 Marley Sigma Steel Cooling Tower Engineering Data Inlet Piping Le gt lt D T C gt TYP SINGLE CELL FAN TYP MULTICELL FAN COLUMN AND q INLET INLET COLUMN AND ANCHOR BOLT ANCHOR BOLT Ly F MIN REQUIRED CLEARANCE
36. 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 expen sive two speed option They are also available in other combi nations 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 abso lute 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 tem perature 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 Specification Value Base Furnish and install an induced draft crossflow type field erected steel framed PVC fill industrial duty co
37. uipment 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 E The driveshaft turns at the motor speed and is therefore most sensi tive to operational imbalance Stainless steel manufacture assures that the driveshaft will not become unbalanced as a result of corrosion E 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 E 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 war ranty satisfaction Marley Sigma Steel Cooling Tower Specifications Base Fill Louvers and Drift Eliminators 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
38. very feasible solution in most areas of the world but the need to avoid cycling may cause the cold water temperature to vary significantly 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 temperature This is a relatively inexpen sive 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 2 3 fan speed or 10 dBA at half fan speed e 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 Your Marley sales representative will help you meet your sound requirements Enclosures Occasionally cooling towers are located inside architec tural enclosures for aesthetic reasons Although Sigma tow ers 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
39. wner 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 Marley Sigma Steel Cooling Tower Specifications Options Specifications Specification Value Convenience and Safety Options Stairway Replace paragraph 9 3 with the fol lowing 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 string ers Stairway posts guardrails and toeboards shall be as specified per Paragraph 9 2 Structural steel sup port columns for the stairway shall be provided by the cooling tower manu facturer 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 Add the following to the end of this paragraph Provide a 30 wide bar grat ing walkway extending from one endwall access door to the other in each cell This walkway shall be supported by a galva nized 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 s
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