SPX Cooling Technologies SS-NC-08A User's Manual
Contents
1. SPX COOLING TECHNOLOGIES UK LTD GREGORY S BANK WORCESTER WR3 8AB UNITED KINGDOM 44 0 1905 720 200 info uk 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 uk_SPEC SS NC 08A2. Marley NC Class Stainless Crossflow Cooling Tower Product Specifications i COOLING TECHNOLOGIES Marley NC Class Stainless Cooling Tower Contents Specifications Base Base Thermal Performance Performance Warranty Design Loading Construction Mechanical Equipment Fill Louvers and Drift Eliminators Hot Water Distribution System Casing Fan Deck and Fan Cylinder Access Cold Water Collection Basin Specifications Options Convenience and Safety Options Guardrail and Ladder Ladder Extension Ladder Safety Cage Ladder Safety Gate Access Door Platform Plenum Walkway Interior Mechanical Equipment Access Platform Control Options Fan Motor Starter Control Panel Vibration Limit Switch Basin Heater Electric Water Level Control Fan Motor Variable Speed Drive Marley Premium VFD System Miscellaneous Options Motor Outside of the Airstream Fan Cylinder Extensions Inlet Flow Control Valves Equalizer Flume Weir Gate Sound Control Inlet Sound Attenuators Outlet Sound Attenuators Low Noise Fan Ultra Low Noise Fan Single Hot Water Inlet Connection Air Inlet Screens High Wind Seismic Designs Multicell Basin Equalizer Outlets Basin Sweeper Piping Extended Geareducer Lube Line Dipstick COMO OMOON OAH HRA oS 11 11 11 11 12 12 12 14 15 15 15 16 17 18 18 19 19 19 19 20 20 21 21 21 21 22 22 22 Marley NC Class Stainless Cooling Tower NC Class St
3. but with approximately 2m clear headroom Outside the tower stainless steel safety cage material is not normally considered necessary If you air quality is sufficiently poor to warrant stainless steel change the specification wording accordingly E A galvanized self closing gate located at the guardrail level of the fan deck exterior motor access platform and access door platform Stainless steel is available with the stainless guardrail option Marley NC Class Stainless Cooling Tower Specifications Options GUARDRAIL ACCESS DOOR PLATFORM LADDER EXTENSION N N N Marley NC Class Stainless Cooling Tower Specifications Options Specification Value Access Door Platform Add the following paragraph in the Access section There shall be an access platform at the base of the tower extending from the vertical lad der to the endwall access door The platform shall be galvanized steel bar grating supported by galvanized steel E Where towers are installed on an elevated grillage or piers it is often difficult to get to and through the access door conve niently This platform provides easy safe a
4. rail and kneerail system NOTE OSHA and other concerned authorities are in the process of developing guidelines regarding the safety procedures and protective equipment that should be provided maintenance per sonnel who are required to go inside cooling towers We feel it advisable to provide for as much maintenance as possible from outside the cooling tower and to that end offer such options as Guardrail and Ladder pg 11 Ladder Extension pg 11 Ladder Safety Cage pg 11 Access Door Platform pg 13 and Motor Out of the Airstream pg 18 Such interior convenience options as Plenum Walkway pg 13 that are offered are not meant as an invitation to perform inside maintenance They are intended solely to maximize the comfort and safety of maintenance per sonnel during the performance of any inside work may become necessary Marley NC Class Stainless Cooling Tower Specifications Options Specification Value Control Options Fan Motor Starter Control Panel Add the following paragraph in the Mechanical Equipment sec tion Each cell of the cooling tower shall be equipped with a UL listed control system in a IP14 or IP56 out door enclosure capable of controlling single speed or two speed motors as required and designed specifically for cooling tower applications The panel shall include a main fused disconnect or main circuit breaker with an external operating handle lockable in the off position for safety Acr
5. Access section A hole and bolt circle shall be provided in the depressed sec tion of the basin for equalizer piping between cells A full face 25 thick 50 durometer gasket shall be provided at each equalizer location Basin Sweeper Piping Add the following paragraph in the Access section The cold water basin shall be equipped with PVC sweeper piping with plastic eductor nozzles The piping should create a grid under the fill and force all dirt and debris to the depressed section of the collection basin Extended Geareducer Lube Line with Dipstick Add the following paragraph in the Mechanical Equipment section An external oil level dipstick shall be locat ed adjacent to the motor at the fan deck surface and shall be accessible from a portable maintenance ladder E Used as water level equalizers between multicell towers Not intended for water migration Piping and attachment hardware by others Flat faced flange required E PVC sweeper piping and Lakos nozzles Designed for the following flows at 20 psig NC8301 thru NC8304 33m h NC8305 47m3 h NC8306 thru NC8312 64m h E The dipstick option is accessible from a portable maintenance ladder on one and two cell towers only Maintenance considerations recom mends this option be combined with the ladder and guardrail option on installations of three or more cells since the dipstick cannot be reached without accessing the fan deck SP COOLING TECHNOLOGIES
6. basin water in which zinc ions are pres ent copper immersion heat ers must not be used Insist upon stainless steel The ambient air temperature that you insert in the specifi cations should be the lowest 1 level of winter tempera ture prevalent at site E Solid state liquid level controls provide you with state of the art sys tems to control and monitor the water level in your cooling tower col lection basin Relays operating in conjunction with suspended stainless steel electrode probes monitor basin water levels providing simple solenoid valve water makeup or discrete on off signals to more sophis ticated automation controls Optional configurations might include makeup along with high and low water level alarm and cutoff or pump cutoff Packaged systems including any of these variations are available Consult you Marley sales representative or download a copy of ACC NC 9D from spxcooling com for additional information Marley NC Class Stainless Cooling Tower Specifications Options Specification Value in quantities and locations as indicated on the drawings An overflow and drain connection shall be provided in each cell of the cooling tower The basin floor shall slope toward the drain to allow complete flush out of debris and silt which may accumulate Towers of more than one cell shall include stain less steel flumes for flow and equal ization between cells The basin shall be accessible and maintainable
7. cleaning Air inlet faces of the tower shall be free of water splash out Fill shall be capable of withstanding a hot water tempera ture of 52 C Drift eliminators shall be PVC triple pass and shall limit drift losses to 0 005 or less of the design water flow rate LOUVERS 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 and waste water If you plan to use your tower in the win tertime particularly for free cooling integral louvers will put your operat ing concerns to rest Integral louvers offer the best available technology for winter operation and water conserva tion d Fill options are available for hot water temperatures up to 60 C E Drift rate varies with design water loading and air rate as well as drift eliminator depth and number of directional changes A drift rate of 0 001 is readily available in standard configuration without premium cost If a lower rate is required please discuss with your Marley sales representative Keep in mind e Drift for towers with three pass high efficiency eliminators constitute a small percentage of water usage e Unlike thermal performance drift rates are not certified and field drift tests are cost prohibitive for most applications e Drift rates
8. collection basin a crossflow tower air inlet is still quieter Plus you do not have to worry about clog ging the splash matting Yet another maintenance and operation advan tage of the crossflow configuration E NC Class models with the L suffix in the model number are the special low sound editions To achieve the very lowest possible sound levels while maintaining efficiency the best available combination of motor gear ratio fan blade count and blade profile were carefully selected for every L model All L models come with the Low Noise Fan option If you choose the sound attenuator option the fan will automatically change to the Low Noise Fan option HTip Speed unlike thermal performance no certification program exists for sound While Marley conducts actual sound tests on all its configura tions there are only a few ways for the client to ensure they get a quiet tower e One is to conduct a field sound test after installation On site testing after installation can however be inaccurate depend ing on the environ ment e Another is to conduct a sound test at the factory However both can be cost prohibitive for smaller applications e Specifying fan blade tip speed is one way to physically force the tower selection to be quiet Tip speed is easily checked by multiplying the fan rpm by the fan circumference at the blade tip a fan dia Over 61m s is considered high by most people 51 61 is considere
9. ainless Steel towers are factory assembled crossflow cooling towers designed to serve air conditioning and refrigeration systems as well as light to medium industrial process loads on clean water They evolve from a factory assembled concept of towers pioneered by Marley some 50 years ago and incorporate all of the design advancements that our customers have found valuable The NC Class has been designed specifically for sound control and tonnage density and represents the current state of the art in this cooling tower category This booklet not only relates the language to use in describing an appropriate NC Class cooling tower but also defines why certain items and features are important enough to specify with the intention of insisting upon compliance by all bidders The left hand column of pages 4 thru 22 provides appropriate text for the various specification paragraphs whereas the right hand column comments on the meaning of the subject matter and explains its value Pages 4 thru 10 indicate those paragraphs which will result in the purchase of a basic cooling tower one that accomplishes the specified thermal performance but which will lack many operation and maintenance enhancing accessories and features that are usually desired by those persons who are responsible for the continued and continuing operation of the system of which the tower is part It will also incorporate those standard materials which testing and experienc
10. alue designed for 2 4kPa live load or a 91kg concentrated load Guardrails where specified shall be capable of with standing a 890N concentrated live load in any direction and shall be designed in accordance with OSHA guidelines Construction Except where otherwise specified all components of the cooling tower shall be fabricated of heavy gauge series 300 stainless steel The tower shall be capable of withstanding water having a chloride content NaCl up to 750 mg L a sulfate content SO4 up to 1200 mg L a calcium content CaCO3 up to 800 ppm silica SiO2 up to 150 mg L and design hot water temperatures up to 52 C The circulating water shall contain no oil grease fatty acids or organic solvents The specifications as written are intended to indicate those materials that will be capable of withstanding the above water quality in continuing service as well as the loads described in paragraph 4 1 They are to be regard ed as minimum requirements Where component materials peculiar to indi vidual tower designs are not specified the manufacturers shall take the above water quality and load carrying capabili ties into account in the selection of their materials of manufacture shipped handled hoisted and ultimately operated in a normal cooling tower environment Most NC Class models will withstand significantly higher wind and seismic loads If your geographic location dictates higher wind load or sei
11. below 0 001 are difficult to measure in the field e Certain water treatment chemicals can impact the drift rate DRIFT ELIMINATOR separate from fill on some models Marley NC Class Stainless Cooling Tower Specifications Base Specification Value Hot Water Distribution System Two stainless steel open basins one above each bank of fill shall receive hot water piped to each cell of the tower These basins shall be installed and sealed at the factory and shall be equipped with removable stainless steel covers capable of withstanding the loads described in paragraph 4 1 All components of these basins with the exception of the nozzles shall be stainless steel The water distribution system shall be accessible and main tainable during tower fan and water operation Each basin shall include an inlet hole and bolt circle to accept a 125 flange connection per ANSI B16 1 Removable interchangeable polypro pylene nozzles installed in the floor of these basins shall provide full coverage of the fill by gravity flow The water distribution system shall be accessible and maintainable while tower is operating Casing Fan Deck and Fan Guard The casing and fan deck shall be heavy gauge stainless steel and shall be capable of withstanding the loads described in paragraph 4 1 The top of the fan cylinder shall be equipped with a conical non sagging removable fan guard fabricated of welded 8mm and 7 gauge rods and
12. ce test under the supervision of a qualified disinterested third party in accordance with CTI or ASME standards during the first year of operation and if the tower fails to perform within the limits of test tolerance then the cooling tower manufacturer will pay for the cost of the test and will make such corrections as are appropriate and agreeable to the owner to compensate for the perfor mance deficiency Warranty The entire tower including struc ture casing basins decking fan s motor s and all mechanical drive com ponents including belts if used shall be warranted against failure due to defects in materials and workmanship for a period of five 5 years from the date of shipment to the job Towers not covered by a warranty of this scope will not be accepted Design Loading The tower structure anchorage and all its components shall be designed by licensed structural engineers per the International Building Code to with stand a wind load of 1 44k Pa as well as a 3g seismic load The fan deck and hot water basin covers shall be Specification Value E CTI Certification means that the tower has been tested under operating condi tions and found to perform as rated by the manufacturer under those circum stances It assures the buyer that the tower is not intentionally or inadvertent ly undersized by the manufacturer CERTIFIED The minimum efficiency per ASHRAE Standard 90 1 for induced draft
13. creens Add the following paragraph to the Casing Fan Deck and Fan Guard sec tion The air inlet faces of the tower shall be covered by 1 mesh hot dipped galvanized welded wire screens Screens shall be secured to removable galvanized U edge frames High Wind Load Seismic Designs Replace this paragraph with the fol lowing The tower structure anchor age and all its components shall be designed by licensed structural engineers per the international build ing code to withstand a wind load of gt E For more severe cases requiring the lowest possible fan sound levels the Marley Ultra Low Noise fan option is now available on all but the NC8301 NC Class models Tower height may increase slightly obtain current sales drawings from your Marley sales representative for accu rate dimensions If your requirement calls for inlet and outlet attenu ation you might consider the Ultra Low Noise fan in lieu of attenua tion Outlet attenuators are not available with the Ultra Low Noise Fan option This option reduces what might otherwise be a complex hot water piping layout to a simple single connection per cell It also avoids an unsightly perhaps unsafe maze of pipe exposed above the top deck of the tower The single inlet connection can be located either in the tower s endwall casing or below the cold water basin The endwall entry point is suit able for single cell towers and for those that might be installed in gr
14. d reliability and low maintenance Ideal for owners concerned about downtime or maintenance costs Currently available on 49 NC models the Marley Power Belt drive system features all aluminum sheaves power band belts and long life bearings for dependable ser vice TEFC motors offer additional benefits over TEAO motors whose only source of cooling is the flow of air produced by the cooling tower fan This air rate is not always ideal due to motor position blockage etc TEFC ensures the motor will always be cooled properly Unless otherwise specified motor speed will be 1500 RPM on standard models Low noise models will use motor speeds appropriate for the specific model If you prefer the operating flexibility of two speed oper ation please specify two speed single winding motors which offer full and half speeds for maximum energy savings Incidentally two speed motors are a better choice than separate pony motors which simply double the problems indicated above and induce parasitic loads during operation for lower than nameplate efficiency Marley NC Class Stainless Cooling Tower Specifications Base Fill Louvers and Drift Eliminators Fill shall be film type thermoformed of 0 40mm thick PVC with louvers formed as part of each fill sheet Fill shall be suspended from hot dip gal vanized structural tubing supported from the tower structure and shall be elevated above the floor of the cold water basin to facilitate
15. d typical and expect ed 41 51 would be considered low noise Below 41 is difficult to hear above the water noise Marley NC Class Stainless Cooling Tower Specifications Options 21 Specification Value Ultra Low Noise Fan Replace paragraph 6 1 with the fol lowing Fan s shall be propellertype incorporating wide chord forward swept FRP blades and galvanized hubs Blades shall be individually adjustable Maximum fan tip speed shall be 51 m s Fan s shall be driven through a right angle industrial duty oil lubricated geared speed reducer that requires no oil changes for the first five 5 years of operation The gearbox bearings shall be rated at an Lio Ser vice life of 100 000 hours or greater Available on Models NC8302 through NC8312 Single Hot Water Inlet Connection per Cell Replace this paragraph with the following Each cell of the tower shall include a single hot water inlet connection located as shown on the plans An internal system of piping shall deliver water equally to the dis tribution basins without the need for balancing valves This internal piping system shall require no scheduled maintenance and shall be located such that it does not interfere with normal maintenance access The internal pip ing must extend to the tower exterior Removable interchangeable polypro pylene nozzles installed in the floor of these basins shall provide full coverage of the fill by gravity flow Air Inlet S
16. e has proven to provide acceptable longevity in normal operating conditions Pages 11 thru 22 provide paragraphs intended to add those features components and materials that will customize the tower to meet the user s requirements Space does not permit definition and explanation of all of the possible options that can be applied to the NC Class We realize that you the purchaser must be happy with the tower s characteristics and we are prepared to provide or provide for any reasonable enhancement that you are willing to define and purchase Your needs will become part of the continuing evolution of this Marley product line Marley NC Class Stainless Cooling Tower Specifications Base Specification Value Base Provide an induced draft crossflow type factory assembled film fill industrial duty stainless steel cooling tower situated as shown on the plans The limiting overall dimensions of the tower shall be wide long and high Total operating kilowatt of all fans shall not exceed kW consisting of ___ kW motor s Tower shall be similar and equal in all respects to Marley Model E Your specification base establishes the type configuration base materi al and physical limitations of the cooling tower to be quoted During the planning and layout stages of your project you will have focused your attention on a cooling tower selection that fits your space allotment a
17. e 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 E Marley Variable Speed Drive systems are designed to combine absolute temperature control with ideal energy management The cooling tower user selects a cold water temperature and the drive system will vary the fan speed to maintain that temperature Precise temperature control is accomplished with far less stress to the mechanical equipment compo nents The improved energy management provides fast payback to the user Marley NC Class Stainless Cooling Tower Specifications Options X Specification Value cold water temperature The application must be able to handle very cold water while 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 cooling tower 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 cooling tower 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 Pr
18. emium 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 IP52 indoor or IP14 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 pro tection and external operating handle lockable in the off position for safety The system shall include a solid state PI temperature controller to adjust fre quency output of the drive in response to the tower cold water temperature The temperature of the cold water 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 the bypass mode shall be automatic in the event of VFD failure or for specific trip conditions allowing safe transfer of utility voltage to the motor Automatic bypass with an earth ground condition is not allowed The bypass contactor shall be cycled on and off while operating in bypass to maintain the set point temper ature of the cold water The drive design Marley NC Class Stainless Cooling Tower Specifications Op
19. g means of flow regulation between hot water basins and between cells of multicell towers as well E Where it is your intention to be able to operate both cells of the tower while the flume cover plate is installed separate outlet connections float valves and overflows must be provided for each cell Likewise this would require separate sensors and controls for basin heater systems if installed E Sound produced by a standard NC Cooling Tower operating in an unobstructed environ ment will meet all but the most restrictive noise limitations and will react favorably to natural attenuation Where the cooling 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 dB A 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 e Where only a slight reduction in noise will satisfy and the source of concern is in a particular direction merely turning the cooling tower may be the answer Less sound emanates from the cased face of the cooling 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 operating the fans a
20. ga service life of 40 000 hours or greater Currently available on Models NC8304 through NC8309 Motor s shall be ____ kW maximum TEFC 1 15 service factor variable torque and specially insulated for cool ing tower duty Speed and electrical characteristics shall be RPM single winding __ phase ____ hertz volts Motor shall operate in the shaft horizontal position and name plate kilowatt shall not be exceeded at design operation The complete mechanical equipment assembly for each cell shall be support ed by a rigid steel structural support that resists misalignment between the motor and the gear reducer lM The Marley NC is the only crossflow cooling tower approved for single cell FM installations This could have a very beneficial effect upon your fire insurance premiums Towers not able to meet FM requirements may require the inclusion of a fire protection sprinkler system to achieve a comparable level of insur APPROVED ance premium cost Even if you are not insured by FM this requirement ensures that each cell will contain any fire that may occur without losing the ability of limited operations and capacity E Propeller type fans require only half the operating hp of blower type fans However they should be readily adjustable to permit compensa tion for jobsite conditions With NC the choice is yours The exclusive Marley System5 Geareducer requires no oil changes for five years offering you unmatche
21. hot dip galvanized after fabrication Fan cylinders 1 5m in height and over shall not be required to have a fan guard E Gravity flow distribution basins are a feature of crossflow type tow ers resulting in operating pump heads of 3 to 6 meters less than that encountered in counterflow towers with pressurized spray systems Also these basins are located where they can be easily inspected even maintained while the tower is in operation E Some manufacturers require shutting down the tower to clean the dis tribution system Can you afford to do that E Materials other than heavy gauge steel for fan decks may be unable to meet your specified loading requirements See remarks Guardrail and Ladder on page 13 In addition steel is excellent at resisting damage cracking UV and fire The heavy construction of the Marley fan guard generally precludes the need for stainless steel material If you would prefer these to be stain less steel please adjust the word ing of the last sen tence accordingly Oo io b Marley NC Class Stainless Cooling Tower Specifications Base Access A large stainless steel rectangular access door shall be located on both end panels for entry into the cold water basin Doors shall provide access to the fan plenum area to facili tate inspection and allow maintenance to the fan drive system Cold Water Collection Basin The collection basin sha
22. ided to elevate the fan dis charge to a height of ___ m above the fan deck level E For many years a feature of Marley cooling towers was that the electric motors were located outside the fan cylinders where they were easily accessible and where they were not subjected to the constant humidity that exists inside the tower plenum Although improved motor designs insulation bearings seals and lubricants have now made it fea sible for us to locate the motor inside the tower in close coupled prox imity to the Geareducer page 7 many users still prefer the motor to be located outside the humid airstream If you are among those users or are among those who see the wisdom of their thinking please spec ify this option If you do however please require it of all bidders E Extensions are available in 305mm increments to a maximum height equal to the diameter of the fan Such extensions may be considered necessary in order to elevate the discharge beyond the bounds of an enclosure Discuss applicability with your local Marley sales representa tive b N Marley NC Class Stainless Cooling Tower Specifications Options 19 Specification Value Inlet Flow Control Valves Add the following to the end of the paragraph Heavy duty flow regulator valves shall be provided at the hot water inlet connections These valves shall be disc type with cast iron bodies and stainless steel operating stems The
23. latively immune to poor water quality Where such conditions do exist how ever thought should be given to the prevention of such carryover or to the use of a Marley splash fill product Please discuss your situation with your Marley sales representative Factory Assembly 5 3 Marley NC Class Stainless Cooling Tower Specifications Base Specification Value The tower shall include all design and material modifications necessary to meet the fire rating requirements of Factory Mutual The product proposed shall be listed in the FM Approval Guide latest edition Standard on models NC8301 thru NC8309 Available as an option on models NC8310 thru NC8312 Mechanical Equipment Fan s shall be propellertype incor porating wide chord aluminum alloy blades and galvanized hubs Blades shall be individually adjustable Maximum fan tip speed shall be 66 m s Fan s shall be driven through a right angle industrial duty oil lubricat ed geared speed reducer that requires no oil changes for the first five 5 years of operation The gearbox bear ings shall be rated at an Liga service life of 100 000 hours or greater alternate Fan s shall be propeller type incorporating wide chord alumi num alloy blades and galvanized hubs Blades shall be individually adjustable Fan s shall be driven through a one piece multi groove solid back V type belt pulleys and tapered roller bear ings Bearings shall be rated at an Li
24. ll be heavy gauge S300 stainless steel and shall include the number and type of suction connections required to accommodate the outflow piping system shown on the plans Suction connections shall be equipped with stainless steel debris screens A factory installed float oper ated mechanical make up valve shall be included An overflow and drain connection shall be provided in each cell of the cooling tower The basin floor shall slope toward the drain to allow complete flush out of debris and silt which may accumulate Towers of more than one cell shall include stain less steel flumes for flow and equal ization between cells The basin shall be accessible and maintainable while water is circulating Specification Value E The access doors on NC8301 and NC8302 towers are 76cm wide by 84cm high On NC8303 thru NC8312 the access doors are 122cm high Small access doors are prohibitive and discourage maintenance which in turn can impact your operation Specifying the size of the door will cause some bidders to take excep tion alerting you to a potential maintenance headache Two doors are standard on all NC Class tow ers one in each endwall E The NC tower design offers side suctions side outlet sumps and bottom outlets to accommodate a significant variety of piping schemes Unless so specified the tower you may be asked to approve may only be available with one type of suction connection requiring you to redesig
25. n your piping layout N N es et eX Marley NC Class Stainless Cooling Tower Specifications Options Convenience and Safety Options Guardrail and Ladder Add the following paragraph in the Access section The top of the tower shall be equipped with a sturdy guardrail complete with kneerail and toeboard designed according to OSHA guidelines and factory welded into subassemblies for ease of field instal lation Posts toprails and kneerails shall be 388mm square tubing The guardrail assembly shall be hot dipped galvanized after welding and capable of withstanding a 890N concentrated live load in any direction Posts shall be spaced on centers of 2 4m or less A 46cm wide aluminum ladder with 76mm l beam side rails and 32mm diameter rungs shall be permanently attached to the endwall casing of the tower rising from the base of the tower to the top of the guardrail Ladder Extension Add the following to the end of the above paragraph Provide a ladder extension for connection to the foot 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 The installing contractor shall be respon sible for cutting the ladder to length attaching it to the foot of the tower lad der and anchoring it at its base Ladder Safety Cage Add the following paragraph in the Access section A heavy gauge galva
26. nd comfortable access to that door It also extends beyond the door to provide ready access to the optional Control System See drawing on page 12 Outside the tower stainless steel platform material is not normal framework attached to the tower ly considered necessary If you air quality is sufficiently poor to The platform shall be surrounded by a warrant stainless steel change the specification wording accord guardrail kneerail and toeboard ingly Plenum Walkway Add the following paragraph in the Access section Provide a factory installed galvanized steel bar grating walkway extending from one endwall access door to the other endwall This walkway shall be supported by a gal vanized steel framework and the top of the grating shall be at or above the cold water basin overflow level Interior Mechanical Equipment Access Platform C8303 thru NC8309 Add the following paragraph in the Access section A factory installed elevated galvanized bar grating plat form convenient to the care and main tenance of the tower s mechanical equipment shall be provided Interior Mechanical Equipment Access Platform C8310 thru NC8312 N Add the following paragraph in the Access section An internal ladder shall extend upward from the plenum walkway to an elevated galvanized bar grating platform convenient to the care and maintenance of the tower s mechanical equipment The platform shall be surrounded by a sturdy guard
27. nd whose power usage is acceptable Limitations on physical size and total operating horsepower avoid the introduction of unforeseen opera tional and site related influences Specifying the number of cells and the maximum fan kW cell will work to your advantage The benefit of crossflow towers is that they are inherently easy to oper ate access and maintain Compared to counterflow towers crossflow towers have a spacious plenum between banks of fill for easy access to all of the tower s internal components plus the water distribution sys tem is adjacent to the fan deck and can be maintained during operation The NC is also available unassembled for on site assembly 3 1 Marley NC Class Stainless Cooling Tower Specifications Base Thermal Performance and Efficiency The tower shall be capable of cooling m3 h of water from ___ C to C at a design entering air wet bulb temperature of C and its thermal rating shall be Certified by the Cooling Technology Institute The tower shall be capable of a mini mum m h kilowatt efficiency per ASHRAE Standard 90 1 CTI Certification notwithstanding the cooling tower manufacturer shall guarantee that the tower supplied will meet the specified performance conditions when the tower is installed according to plan If because of a suspected thermal performance defi ciency the owner chooses to conduct an on site thermal performan
28. nized steel safety cage shall surround the ladder extending from a point approximately 2m above the foot of the ladder to the top of the guardrail Ladder Safety Gate Add the following paragraph in the Access section A galvanized steel self closing gate shall be provided at the guardrail level of the ladder 11 Specification Value E The NC Class cooling tower has been designed to minimize the need for mainte nance personnel to get on top of the tower to perform maintenance and inspections For the comfort and safety of your operat ing personnel we recommend that you specify a ladder and guardrail and that you require it of all bidders Although not required for safe operation by OSHA many user s own safety rules may dictate these options Outside the tower stainless steel guardrail material is not normally considered necessary If you air quality is sufficiently poor to warrant stainless steel change the specifica tion wording accordingly E Many towers are installed such that the base of the tower is 61cm or more above the roof or grade level This makes it difficult to get up to the foot of the attached ladder The ladder extension alleviates this problem Marley ladder extensions are available in standard 1 5m and 3 3m lengths E To meet OSHA guidelines towers whose fan decks are 6m or more above roof or grade and which are equipped with lad ders should have safety cages surrounding the ladders
29. open cooling towers applied to comfort cooling is 8 68 kW 35 29 5 24 There are no efficiency requirements for non comfort cooling applications If you want greater efficiency you can require it by specifying a higher ASHRAE Standard 90 1 m h kilowatt CTi E CTI certification alone is not sufficient to assure you that the tower will perform satisfactorily in your situation Certification is established under relatively controlled conditions and towers seldom operate under such ideal circumstances They are affected by nearby structures machinery enclosures effluent from other towers etc Responsible and knowledgeable bidders will take such site specific effects into consider ation in selecting the tower but the specifier must insist by the written specification that the designer manufacturer guarantee this real world performance Any reluctance on the part of the bidder should cause you some concern E It is important to understand the distinction between structure and anchorage Specifying that only the anchorage meet these require ments means the tower can become non functional even fall down yet remain attached to the foundation Specifying structure will require the tower to remain operational The indicated design values are the minimum allowables under accept ed design standards They give you assurance that the tower can be gt Marley NC Class Stainless Cooling Tower Specifications Base Specification V
30. oss the line mag netic starters or solid state soft start starters as required shall be controlled with a thermostatic or solid state temperature controller Door mounted selector switches shall be provided to enable automatic or manual control and wired for 240VAC control Control circuit to be wired out to terminal blocks for field connection to a remote vibration switch overload trip alarms and remote temperature control devic es The temperature controller shall be adjustable for the required cold water temperature If a thermostatic control ler is used it shall be mounted on the side of the tower with the temperature sensing bulb installed in the cold water basin using a Suspension mounting bracket If a solid state temperature controller is used the controller will be door mounted on the control panel The temperature controller will display two temperatures one for outgoing water and the other for set point Water temperature input shall be obtained using a three wire RTD with dry well in the outlet water piping and wired back to the solid state tempera ture controller in the control panel E f it is your opinion that the control system for the cooling tower 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 cooling tower s operation and to apply a system most compatible with it than the design er and manufac
31. oups of two cells each Bottom inlet piping lends itself to close spaced multicell installations and to those situations where it is appro priate to keep all pipework below the level of the tower Be sure to specify that the internal pipe extends to the tower exterior panel either the casing panel or collection basin floor Some manufac turers require the contractor to complete the internal piping adding to your cost E In wooded or windy areas these screens help to keep leaves or blowing debris out of the cool ing tower and circulating water system E High wind load designs greater than 30 psf are available up to 100 psf It is important to consult the local code official for actual requirements Some manufacturers will claim their tower is capable but have never had the design reviewed by a licensed structural expert Not requiring expert review for high wind and seismic regions is dangerous to you and the public x Marley NC Class Stainless Cooling Tower Specifications Options 22 Specification Value psf as well as a seismic load The fan deck and hot water basin covers shall be designed for 50 psf live load or a 200 Ib concentrated load Guardrails where specified shall be capable of withstanding a 200 Ib con centrated live load in any direction and shall be designed in accordance with OSHA guidelines Multicell Basin Equalizer Outlets Add the following paragraph in the
32. rbox bearings shall be rated at an Liga service life of 100 000 hours or greater alternate Fan s shall be propeller type incorporating a minimum of seven wide chord aluminum alloy blades and galvanized hubs Blades shall be individually adjustable Fan s shall be driven through a one piece multi groove solid back V type belt pulleys and tapered roller bearings Bearings shall be rated at an Liga ser vice life of 40 000 hours or greater Currently available on Models NC8304 through NC8309 temperature without sacrificing the system s ability to maintain a con stant cold water temperature This is a relatively inexpensive solution and can pay for itself quickly in reduced energy costs eThe most extreme cases may require inlet and discharge sound attenu ator sections however the static pressure loss imposed by discharge attenuators may necessitate an increase in tower size Two stages of inlet or discharge attenuators supported by the tower and designed and tested for the most stringent requirements are available as an option E Falling water sound unlike counterflow towers which allow the water to free fall and splash into the cold water collection basin PVC film fill crossflow towers have no splashing This allows a crossflow tower much lower sound levels at the air inlet than a counterflow tower especially induced draft counterflow towers Even with the splash mat ting option in a counterflow cold water
33. re shall be a locking handle to maintain the valve setting in any position Valves shall be right angle configuration precluding the need for inlet elbows Equalizer Flume Weir Gates Add the following paragraph under Cold Water Collection Basin The interconnecting flume between cells shall be equipped with a removable cover plate to permit the shutdown of one cell for maintenance purposes or to permit independent cell operation Sound Control Add the following paragraph under Base The cooling tower shall be quiet operation and shall produce an overall level of sound not higher than dB A measured at m from the locations in the table below All low noise options and combinations shall be CTI Certified for thermal perfor mance Location 63 125 250 500 1000 Discharge Air Inlet Cased Face Location 2000 4000 8000 Overall dB A Discharge Air Inlet Cased Face Inlet Sound Attenuation Add the following paragraph under Base The cooling tower shall be equipped with inlet sound attenuation baffles positioned and spaced verti cally The baffles will be spaced across the entire length and extend the full height of the air inlet The baffles will be constructed of perforated sheet metal and contained within a steel gt E Marley flow control valves have been a favorite of users since the 1950s They remain serviceable for the life of the tower and provide a continuin
34. smic load values please make the appropriate changes after discussion with your Marley sales representative Note Some countries and states Florida require structure not anchor age Check with you local officials 1 44k Pa windload 3g seismic load applicable for most applications but consult the local code official for actual requirements 2 4kPa live load 890N concentrated load ensures the tower can be safely accessed for routine maintenance when a guardrail is installed as well ensuring the end user complies with government safety laws E For pure resistance to corrosion coupled with the capability to meet stringent fire and building codes there is no substitute for stainless steel No paints or electrostatically applied coatings however exotic they may be can match stainless steel s ability to withstand adverse operating conditions Although SPX Cooling Technologies makes use of many structural FRP components in various other product lines they are held to a relative minimum in the NC Class Stainless line This is to assure that there will be no question as to the structural integrity fire resistance and life expectancy in the mind of the owner Except for those unusual operating situations where the circulating water may be so laden with suspended solids algae fatty acids prod uct fibers active organisms reflected in BOD and the like that plug ging of film type fill is a probability the NC Class Stainless is re
35. t 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 A Marley Variable Speed Drive automatically minimize the tower s noise level during periods of reduced load and or reduced ambient Marley NC Class Stainless Cooling Tower Specifications Options 20 Specification Value box which is self supporting The inlet attenuation will not be allowed to impact the thermal performance effi ciency of the basic tower configuration Outlet Sound Attenuation Add the following paragraph under Base The cooling tower shall be equipped with outlet sound attenuation baffles positioned and spaced horizon tally across the entire fan opening The baffles will be constructed of perfo rated sheet metal and contained within a steel box which is self supporting and made of the same material as the tower Low Noise Fan Replace paragraph 6 1 with the fol lowing Fan s shall be propellertype incorporating a minimum of seven wide chord aluminum alloy blades and galvanized hubs Blades shall be individually adjustable Maximum fan tip speed shall be 56 m s Fan s shall be driven through a right angle indus trial duty oil lubricated geared speed reducer that requires no oil changes for the first five 5 years of operation The gea
36. temperature The system shall be capable of maintaining 5 C water tem perature at an ambient air temperature of go Electric Water Level Control Replace this paragraph with the fol lowing The collection basin shall be heavy gauge series 300 stainless steel and shall include the number and type of suction connections required to accommodate the out flow piping sys tem shown on the plans Suction con nections shall be equipped with stain less steel debris screens A solid state water level control system to monitor the water level with a multi relay con trol panel pre wired and mounted in a IP56 nonmetallic enclosure shall be provided The system shall consist of water level sensing and control units gt E Unless specified otherwise a Metrix switch will be provided A double pole double throw model is also available If purchased in conjunction with the Control System it is also factory wired The requirement for manual reset assures that the cooling tower will be vis ited to determine the cause of excess vibration lM The Marley basin heater components described at left represent our rec ommendation for a reliable automatic system for the prevention of basin freezing They are normally shipped separately for installation at the job site by the installing contractor When purchased in conjunction with the enhanced Control System option however they are customarily factory mounted and tested Submerged in
37. tions Specification Value shall be operated as a stand alone sys tem without the need for a BMS system Operator controls shall be mounted on the front of the enclosure and shall consist of start and stop control bypass VFD selector switch Auto Manual selector switch manual speed control and solid state temperature controller An emergency bypass selector switch internal to the panel allowing the cooling tower fan motor to be run at full speed shall be furnished To prevent heating problems in the cooling tower fan motor and to assure proper gear box lubrication the VFD system shall de energize the motor once 25 motor speed is reached and cooling is no longer required The VFD shall include de icing logic with auto canceling and adjustable time Speed in De lce mode shall not exceed 50 motor speed The cooling tower 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 Miscellaneous Options Motor out of the Airstream Add the following to the end of this paragraph The motor shall be mount ed outside the casing of the tower and shall be connected to the gear reducer by a dynamically balanced stainless steel tube and flange driveshaft Fan Cylinder Extensions Insert the following after the first sentence Fan cylinder extensions shall be prov
38. turer of the cooling tower Marley variable speed drives are also available for the ultimate in temperature control energy management and mechanical equip ment longevity See specifications on page 16 N Marley NC Class Stainless Cooling Tower Specifications Options Specifications Specification Value Vibration Limit Switch Add the following paragraph in the Mechanical Equipment section A single pole double throw vibration limit switch in a IP56 housing shall be installed on the mechanical equipment support for wiring into the fan motor shutdown circuit 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 Basin Heater 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 threaded cou plings provided in the side of the basin A IP56 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 cut off A control probe shall be located in the basin to monitor water level and
39. while water is circulating 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 IP10 indoor IP52 indoor or IP14 outdoor enclosure shall be provided The VFD shall use PWM technology with IGBT switching and integrated bypass design VFD out put switching shall not cause mechanical issues with gearbox teeth or drive shafts The VFD shall catch a fan spinning in the reverse direction without tripping The panel shall include a main disconnect with short circuit protection and external operating handle lockable in the off position for safety The VFD system shall receive a speed reference signal from the Building Management System monitoring the tower cold water temperature As an option to receiving the speed reference signal from a build ing management system the drive must have the capability to receive a 4 20 ma temperature signal from an RTD trans mitter The VFD shall have an internal PI regulator to modulate fan speed main taining set point temperature The drive s panel display shall be able to display the set point temperature and cold water temperature on two separate lines The bypass shall include a complete mag netic bypass circuit and with capability to isolate the VFD when in the bypass mode Transfer to the bypass mode shall b
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