Marley NC Series Cooling Tower User Manual
Contents
1. Plugged Oil Lines or Vent Change Geareducer Oll Thoroughly Inspect Mechanical Couplings Check and Tighten as Required Mechanical Equipment Bolts Motor Anchor Bolts Tower Framework Structural Bolts Fan Assembly Bolts Inspect Metal Surfaces and Touchup X Motor Operation Required minimum 3 hrs month 0 Marley Cooling Tower w AUnited Dominion Company The Marley Cooling Tower Company 7401 W 129 Street Overland Park KS 66213 913 664 7400 In the interest of technological progress all products are subject to design and or material change without notice 1999 Marley Cooling Tower Printed in USA2. or in SI units Heat Load kilowatts Range C Liters sec x 4 187 Operation The cooling tower establishes onlythe cold water temperature attainable under any operating circumstance 2 Air wet bulb temperature Cold water temperature will also vary with the wet bulb temperature of the air entering the louvered faces of the tower Reduced wet bulb temperatures will result in colder water temperatures However the cold water temperature will not vary to the same extent as the wet bulb For example a 20 F 11 C reduction in wet bulb may result in only a 15 F 8 C reduction in cold water temperature 3 Water flow rate Increasing the water flow rate GPM or L s will cause a slight elevation in cold water temperature while reducing the water flow rate will cause the cold water temperature to decrease slightly However at a given heat load see formula above water flow reductions a so cause an increase in the incoming hot water temperature Use care to prevent the hot water from exceeding 125 F 52 C in order to prevent damage to the tower components 4 Air flow rate Reducing air flow through the tower causes the cold water temperature to rise This is the approved method by which to control leaving water temperature If your tower is equipped with a single speed motor the motor may be shut off when the water temperature becomes too cold This will cause the water temperature to rise When the water tem
3. including a handrail system around the perimeter of the fan deck with either one or two ladders for access to the deck ladder extensions used where the base of the tower is elevated safety cages for fan deck ladders external lube lines fan cylinder extensions flow control balancing valves access door platform motor located outside the tower external motor access platform Tower Location Space available around the tower should be as generous as possible to promote ease of maintenance and to permit freedom of airflow into and through the tower If you have questions about the adequacy of the available space and the intended configuration of the tower please contact your Marley sales engineer for guidance Prepare a stable level support foundation for the tower utilizing weight wind load and dimensional information appearing on appropriate Marley submittal drawings Supports must be level to insure proper operation of the tower The cooling tower must be located at such distance and direction to avoid the possibility of contaminated tower discharge air being drawn into building fresh air intake ducts The purchaser should obtain the services ofa Licensed Professional Engineer or Registered Architect to certify that the location of the tower is in compliance with applicable air pollution fire and clean air codes A Warning Receiving and Hoisting Tower Shipment Unless otherwis
4. Marley office or representative will be happy to give you copies of these reports at no charge Just call your local office and ask for the Cooling Tower Information Index series For complete parts and service assistance contact the Marley sales or representative office in your area If you need help locating the office nearest you please phone 913 664 7400 and ask for Marketing Services 25 Troubleshooting Trouble Cause Remedy Power not available at motor terminals e Check power at starter Correct any bad connections between the control apparatus and the motor e Check starter contacts and control circuit Reset overloads close contacts reset tripped switches or replace failed control switches e If power is not on all leads at starter make sure overload and short circuit devices are in proper condition Motor Will Not Start Wrong connections Check motor and control connections against wiring diagrams Low voltage Check nameplate voltage against power supply Check voltage at motor terminals Open circuit in motor winding Check stator windings for open circuits Motor or fan drive stuck Disconnect motor from load and check motor and Geareducer for cause of problem Rotor defectve Look for broken bars or rings Motor running single phase Stop motor and attempt to start it Motor will not start if single phased Check wiring controls and motor Motor leads conne
5. flushed by use of a moderate pressure water nozzle being careful not to cause physical damage A reliable water treatment program should be installed and maintained Filtration devices may be employed to reduce the suspended solids concentrations thus increasing the effectiveness of the water treatment program See Tower Startup instructions on page 9 Blowdown A cooling tower cools water by continuously causing a portion of it to evaporate Although the water lost by evaporation is replenished by the makeup system it exits the tower as pure water leaving behind its burden of dissolved solids to concentrate in the remaining water Given no means of control this increasing concentration of contaminants can reach a very high level In order to achieve water quality which is acceptable to the cooling tower as well as the remainder of your circulating water system the selected water treatment company must work from a relatively constant level of concentrations This stabilization of contaminant concentrations is usually accomplished by blowdown which is the constant discharge of a portion of the circulating water to waste As a rule acceptable levels on which to base a treatment schedule will be in the range of 2 4 concentrations The A Note A Warning Maintenance following table shows the minimum amount of blowdown percent of flow required to maintain different concentrations with various cooling ranges Number of Co
6. total of 30 seconds hr Set on off or speed change set points farther apart Consider installing a Marley VFD drive for fine temperature control Deterioration of grease or foreign material in grease Flush bearings and relubricate Bearings damaged Replace bearings Voltage too low at motor terminals Motor Does Not Come Up because of line drop To Speed Check transformer and setting of taps Use higher voltage on transformer terminals or reduce loads Increase wire size or reduce inertia Broken Rotor bars Look for cracks near the rings A new rotor may be required Have motor service person check motor Wrong Rotation Motor Wrong sequence of phases Switch any two of the three motor leads 26 Troubleshooting Trouble Cause Remedy Geareducer bearings Geareducer Noise If new see if noise disappears after one week of operation Drain flush and refill Geareducer See Geareducer Service Manual If still noisy replace Gears Correct tooth engagement Replace badly worn gears Replace gears with imperfect tooth spacing or form Loose bolts and cap screws Tighten all bolts and cap screws on all mechanical equipment and supports Unbalanced drive shaft or worn Make sure motor and Geareducer shafts are in proper alignment and match marks properly matched Repair or replace worn couplings Rebalance drive shaft by adding or couplings removing wei
7. MINCserIEs OM NC2 A Marley Manual 92 1327F A Note A Warning A Caution A Note Contents This manual contains vital information for the proper installation and operation of your cooling tower Carefully read the manual before installation or operation of the tower and follow all instructions Save this manual for future reference TOWer LOGALIOM hss iies ssid oegt asa A EEE A nee ahaa esaeds 4 Tower SHipMentt cccccccecceescceeeeseceeesaeeeeeeeeeeeaaaeseaeeeeeaaaeseeneeeseaaaeseaes 5 RECEIVING FOWE iaic nite ee SE eden chai e eet teed 5 FOISting TOWO aioe eiaa NE AEAEE ANE EAA 5 Tower Installation rieren aee nn EEEE EARE 6 Tower Start Up ircen ainiai aaa iae aiaia at andan faas 9 Tower Operat OT ia Te a eaa aa a a e aa E E A EA ENEAS 12 Wintertime Operation ceccccceecceeeeeeeeeeeeeeceaeeeeeeeeeseaaeeeeeeeeeeeaaeeees 14 Water Treatment and Blowdown ecceeeeeeeeeeeeenneeeeeeeenaaeeeeeeeeeaaes 17 Schedule of Tower Maintenance cccccsceeeeceeeeeeeeeeeeeeeeesseeeeeenes 19 Motor Relubrication Instructions cceeeecseeeeeeeencneeeeeeeeeneeeeeeeeeaaas 21 Seasonal Shutdown Instructions c cccesceeeeeeeeeeeeeeeeeeeeeesenaeeeeneees 22 Prolonged Shutdown c cccccceeeeeeeeeececeeeeeeeeeeeeaeeeeceeeseaeeseceeeesaeees 23 Marley Semice Sirnea aed adnan atl ait de 23 Additional Information 0 ecceeeceeeeeeeeeeeeeeeeeeeeeeeeseeaaeeeeeeeeaaeeeeeesenaaees 25 Tro
8. ange intervals To maintain five year change intervals use only oil designed specifically for these Geareducers If after five years turbine type mineral oil is used the oil must be changed semiannually Refer to the Geareducer Manual for oil recommendations and further instructions Annually Inspect the tower thoroughly making maximum use of instructions given in the separate service manuals Check structural bolted connections and tighten as required Make preventive maintenance repairs as necessary Every 5 Years Change Geareducer oil Refer to Geareducer Service Manual for instructions Motor Relubrication Instructions Motor located outside plenum option Open and lock out disconnect switch to make certain motor cannot be started 1 Remove guard as shown on the next page Opposite end motor bearing is accessible from outside the tower 2 Remove grease fill and relief plugs at both shaft extension end and opposite end bearings and remove hardened grease using clean wire 3 Insert grease fittings in grease fill openings and add grease until grease is forced out through relief openings mB 21 A Note 22 Maintenance Steel Side Casing Attachment Screw Guard Grease Relief Plug 4 Replace fill plugs and operate mechanical equipment 30 minutes to one hour to purge excess grease at grease relief opening 5 Reinstall grease relief plugs and reinstall guard 6 Resume normal tower operatio
9. cer or dipstick standpipe located on fan deck if so equipped to confirm that the proper level is indicated 2 Install top fan ring and fan guard according to the installation drawing shipped with the tower NC1200 through NC3200 models include a single piece fan guard NC4200 through NCC200 models include a two piece fan guard Improper installation of the fan cylinder and fan guard will destroy the structural integrity of the fan guard Failure of the fan guard could allow operating or maintenance personne to fall into the rotating fan 3 Spin the fan manually to assure that all fan blades properly clear the inside of the fan cylinder Observe the action of the coupling or drive shaft couplings to be sure that the motor and Geareducer are properly aligned If necessary correct the alignment in accordance with the included manual It is essential that the fan cylinder and fan guard be installed in accordance with the Field Installation Manual shipped with the tower Do not force the fan cylinder out of round 4 Momentarily bump energize the motor and observe rotation of the fan The fan should rotate in a counterclockwise direction when viewed from below If rotation is backwards shut off the fan and reverse two of the three primary leads supplying power to the motor 11 Z Caution A Note 12 Operation Iftoweris equipped witha two speed motor check for proper rotation at both speeds Check also to see that start
10. cted incorrectly Check motor connections against wiring diagram on motor Bad bearings Check lubrication Replace bad bearings Unusual Motor Noise Electrical unbalance Check voltages and currents of all three lines Correct if required Air gap not uniform Check and correct bracket fits or bearing Rotor unbalance Rebalance Cooling fan hitting end bell guard Reinstall or replace fan Wrong voltage or unbalanced voltage Check voltage and current of all three lines against nameplate values Overload Check fan blade pitch See Fan Service Manual Check for drag in fan drive train as from damaged bearings Wrong motor RPM Check nameplate against power supply Check RPM of motor and gear ratio Bearings overgreased Remove grease reliefs Run motor up to speed to purge excessive grease Wrong lubricant in bearings Change to proper lubricant See motor manufacturer s instructions One phase open Motor Runs Hot Stop motor and attempt to start it Motor will not start if single phased Check wiring controls and motor Poor ventilation Clean motor and check ventilation openings Allow ample ventilation around motor Winding fault Check with Ohmmeter Bent motor shaft Straighten or replace shaft Insufficient grease Remove plugs and regrease bearings Too frequent starting or speed changes Limit cumulative acceleration time to a
11. d as follows e Circulating water with a pH between 6 5 and 8 a chloride content as NaCl below 500 ppm a sulfate content SO4 below 250 ppm total alkalinity as CaCO below 500 ppm calcium hardness as CaCO3 above 50 ppm a maximum inlet water temperature not to exceed 125 F 51 7 C no significant contamination with unusual chemicals or foreign substances and adequate water treatment to minimize scaling e Many systems can be successfully treated with the MarleyOzone System This removes the requirement for other chemical feed systems and provides significant water savings For complete information contact your local Marley office or representative e Chlorine if used shall be added intermittently with a free residual not to exceed 1 ppm maintained for short periods Excessive chlorine levels may deteriorate sealants and other materials of construction e An atmosphere surrounding the tower no worse than moderate industrial where rainfall and fog are no more than slightly acid and they do not contain significant chlorides or hydrogen sulfide H2S e Many proprietary chemicals exist for control of scale corrosion and biological growth and should be used prudently Also combinations of chemicals may cause reactions which reduce treatment effectiveness and certain chemicals such as surfactants biodispersants and antifoams may increase drift rate Unless you purchased a stainless steel NC Diamond Series the s
12. d intended solely to allow personnel to gain access to the fan deck The fan deck ladder should not be used when entering or exiting the maintenance access doors located on the cased face of the tower The purchaser or owner is responsible for providing a safe method for entering or exiting the access door Use of the fan deck ladder to enter or exit the access doors may result in a fall nl 19 A Warning 20 Maintenance Included with this instruction packet are separate Service Manuals on each major operating component of the tower and it is recommended that you read them thoroughly Where discrepancies may exist the separate Service Manuals will take precedence The following is recommended as a minimum routine of scheduled maintenance Always shut off electrical power to the tower fan motor prior to performing any inspections that may involve physical contact with the mechanical or electrical equipment in or on the tower Lock out and tag out any electrical switches to prevent others from turning the power back on Monthly Weekly at start up Observe touch and listen to the tower Become accustomed to its normal appearance sound and level of vibration Abnormal aspects relating to the rotating equipment should be considered reason to shut down the tower until the problem can be located and corrected Observe operation of the motor coupling or drive shaft Geareducer and fan Become familiar with the normal ope
13. e specified NC Series towers ship by truck on flat bed trailers which lets you receive hoist and install the tower in one continuous operation Single cell towers ship on one truck Multicell towers depending on their size may require more than one truck Responsibility for the condition of the tower upon its arrival belongs to the trucker as does the coordination of multiple shipments if required Receiving Tower Prior to unloading the tower from the delivering carrier inspect the shipment for evidence of damage in transit If damage is apparent note the freight bill accordingly This will support your future recovery claim Find and remove the installation instruction drawings and bills of material located in a plastic bag in the cold water basin This information should be kept for future reference and maintenance purposes Hoisting Tower NC8200 NC9200 and NCC200 models consist of two modules per cell The upper module includes hoisting clips at the top of the module The hoisting clips on the lower module are located near the bottom on the sides of the cold water basin All other models ship in a single module The hoisting clips for NCA200 and NCB200 are located near the bottom of the tower on the cold water basin sides The hoisting clips for all other models are located at the top of the tower A Hoisting Installation label is located on the side casing near the tower centerline Remove tower from the carrier and hoist i
14. ention tower serial number shown on the nameplate located on the access door Safety First The location and orientation of the cooling tower can affect the safety of those responsible for installing operating or maintaining the tower However since Marley does not determine the location or orientation of the tower we cannot be responsible for addressing those safety issues that are affected by the tower s location or orientation The following safety issues should be considered by those responsible for designing the tower installation access to and from the fan deck access to and from maintenance access doors e the possible need for ladders either portable or permanent to gain access to the fan deck or maintenance access doors e the possible need for handrails around the fan deck e the possible need for external access platforms e potential access problems due to obstructions surrounding the tower e lockout of mechanical equipment the possible need for safety cages around ladders e theneedtoavoid exposing maintenance personnel to the potentially unsafe environment inside the tower A Warning Preparation Those are only some of the safety issues that may arise in the design process Marley strongly recommends that you consult a safety engineer to be sure thatall safety considerations have been addressed Several options are available that may assist you in addressing some of these personnel safety concerns
15. equired See Page 21 for towers with motor located outside the plenum Do not start motor before determining that there will be no interference with free rotation of the fan drive The motor should be operated for three hours at least once a month This serves to dry out windings and re lubricate bearing surfaces refer to Marley Electric Motor Service Manual At start of new operating season make sure bearings are adequately lubricated before returning motor to service Prolonged Shutdown If shutdown period is longer than seasonal contact your Marley sales engineer for additional information Marley Services Marley s interest in your Series NC cooling tower does not end with the sale Having conceived designed and manufactured the most reliable and longest lasting cooling tower of its class we want to make sure that you gain the maximum possible benefit from its purchase Therefore the following services are available which are intended to assure the maximum possible service life under your operating conditions tailor the operating characteristics to your specific needs and maintain consistently optimum thermal performance capability They are available by contacting your Marley sales representative Replacement parts With the exception of the motor and float valve every standard component of your tower is designed and manufactured by The Marley Cooling Tower Company We do this because commercially available component
16. er is equipped with a 20 second time delay which prevents direct switching from high speed to low speed If the fan is intended to be reversed for deicing purposes make sure that the starter is equipped with a 2 minute time delay between changes of direction These delays will prevent abnormal stress from being applied to the mechanical equipment and the electrical circuit components 5 Runthe motor and observe the operation of the mechanical equipment Operation should be stable and there should be no evidence of oil leakage Ifthe water supply system is not being operated or if there is no heat load on the system motor amps read at this time may indicate an apparent overload of as much as 10 20 This is because of the increased density of unheated air flowing through the fan Determination of an accurate motor load should await the application of the design heat load Tower Operation General The cold water temperature obtained from an operating cooling tower will vary with the following influences 1 Heat load With the fan in full operation if the heat load increases the cold water temperature will rise If the heat load reduces the cold water temperature will reduce Note that the number of degrees range through which the tower cools the water is established by the system heat load and the amount of water being circulated in accordance with the following formula Heat Load Btu hr Range F GPM x 500
17. erflow according to the Field Installation Manual If you wish to pipe overflow and drain water to a remote discharge point make those connections at this time also IB A Caution A Warning Installation 11 Attach your warm water return piping to the inlet connections of the tower Except for the horizontal components of top mounted piping and as prescribed on Marley drawings do not support your pipe from the tower or inlet connection support it externally Normally one of the following four inlet arrangements is provided Standard distribution basin connections These are circular openings two per cell in the top deck of the tower near the air inlet face drilled to accept standard 125 flat face flanges Remove the inlet flume assembly to gain access to attach inlet fasteners Refer to NC Field Installation Manual shipped with tower Marley flow control valve connections option Marley flow control valves two per cell are designed to 1 take the place of the standard elbows normally required for inlet connection and 2 provide means of regulating flow to both sides of the tower Remove the inlet flume assembly to gain access for attachment of valves Refer to NC Field Installation Manual shipped with tower Valves provide a vertical face for attachment of your standard 125 flange Side inlet connection option An appropriately sized hole and bolt circle one per cell is provided in the endwall casin
18. eries and NC Series Modular cooling towers has air entrance louvers that are molded as an integral part of the fill This feature makes these towers very forgiving of cold weather operation even at the low temperature and reduced load conditions encountered in free cooling and other low temperature applications Nevertheless during operation in subfreezing weather the opportunity exists for ice to form in the colder regions of the tower Slushy transitory ice forms routinely in the colder regions of the fill of low temperature towers and is visible through the tower louvers Such ice normally has no adverse effect on tower operation but its appearance should be a signal to the operator to undertake ice control procedures Itis the operator s responsibility to prevent the formation of destructive hard ice on the cooling tower fill Certain guidelines should be followed 1 Do not allow the tower s leaving water temperature to drop below a minimum allowable level say 36 F to 40 F 2 C to 4 5 C If such low temperature operation is necessary or beneficial to your process establish the minimum allowable level as follows During the coldest days of the first winter of operation observe whether any ice is forming on the louver face particularly near the bottom part of the louver face If hard ice is present on the louvers you must increase the allowable cold water temperature If the coldest possible water is beneficial to your proce
19. g above the access door Bolt circle is designed to accept a standard 125 flat face flange Bottom inlet connection option An appropriately sized hole and bolt circle one per cell is provided in the floor of the cold water basin Bolt circle is designed to accept a standard 125 flat face flange 12 Wire motor in accordance with wiring diagram For maintenance safety purposes Marley recommends a lockout type disconnect switch for all mechanical equipment In addition to a disconnect switch the motor should be wired to main power supply through short circuit protection and a magnetic starter with overload protection A Note Operation Tower Start Up Water System 1 Remove any and all accumulated debris from tower Pay particular attention to inside areas of cold water basin hot water basins louvers and drift eliminators Make sure that cold water suction screens are clear and properly installed 2 Fill the water system to an approximate depth of 7 178 mm in the depressed area of the cold water basin at the center of the tower For models NC7200 through NC9200 and models NCB200 and NCC200 fill the water system to an approximate depth of 8 203 mm This is the recommended operating water level Adjust the float valve so that it is 75 open at that level Continue filling the system until the water reaches a level approximately 1 8 3 mm below the lip of the overflow If tower is equipped with a standard
20. ghts from balancing cap screws See Drive Shaft Service Manual Un Fan Driv Make certain all blades are as far from center of fan as safety BOR a ve Fan devices permit All blades must be pitched the same See alio Fan Service Manual Clean off deposit build up on blades Worn Geareducer bearings Check fan and pinion shaft endplay Replace bearings as necessary Disconnect load and operate motor If motor still vibrates Unbalanced motor rebalance rotor Bent Gearsducer shafi Check fan and pinion shaft with dial indicator Replace if necessary Blade rubbing inside of fan cylinder Adjust cylinder to provide blade tip clearance Fan Noise 9 y y p is Loose bolts in blade clamps Insufficient blowdown Scale or foreign substance Check and tighten if necessary See Water Treatment section of this manual in circulating water system Water treatment deficiency Consult competent water treating specialist See Water Treatment section of this manual Entering wet bulb temp is above design Check to see if local heat sources are affecting tower See if surrounding structures are causing recirculation of tower discharge air Discuss remedy with Marley representative Design wet bulb temp was too low May have to increase tower size Discuss remedy with Marley representative Cold Water Temperature Too Warm Actual process load greater than design May have to increase tower size Discuss remedy with Marley represen
21. l valves adjust them to equalize hot water depth in the distribution basins after reaching design water flow rate Each basin should have from 3 to 5 1 2 76 mm to 140 mm water depth with uniform depth from basin to basin Fix valves in this position when depth is correct If the tower is equipped with Marley s internal piping option the basins are self balancing and this step is not necessary Uniform distribution depth of 3 to 5 1 2 76 mm to 140 mm is essential to efficient tower operation Contact your Marley sales engineer if you are considering a permanent change in circulating water flow rate that would prevent operation within these limits Continue pump operation for about 15 minutes after which it is recommended that the water system be drained flushed and refilled While operating the condensing water pump s and prior to operating the cooling tower fan execute one of the two alternative biocidal treatment programs described in the following e Resume treatment with the biocide which had been used prior to shutdown Utilize the services of the water treatment supplier Maintain the maximum recommended biocide residual for the specific biocide for a sufficient period of time residual and time will vary with the biocide to bring the system under good biological control or e Treat the system with sodium hypochlorite to a level of 4 to 5 mg L ppm free chlorine residual at a pH of 7 0 to 7 6 The chlorine resid
22. lace top module on the top peripheral bearing surface factory installed gasket of bottom module aligning mating holes as it is set in place Make sure that the orientation of the top module agrees with your intended piping arrangement Sections are 180 reversible with respect to each other Attach top module to bottom module with fasteners provided according to Field Installation Manual instructions If tower purchased is one cell only ignore steps 4 through 8 4 6 If collection basins are to be equalized by the use of Marley standard flumes unbolt the coverplate from the basin of the cell just installed The coverplate is located in the center of the basin side Unbolt temporary coverplate from the basin of the 2nd cell and set 2nd cell or bottom module of 2nd cell in place Align anchor bolt holes and flume openings in basin sides Install flume according to Field Installation Manual instructions It is important that the cells be firmly anchored before the flume is attached to the 2nd cell Installation Repeat steps 2 and 3 for 2nd top section on NC8200 NC9200 and NCC200 models Repeat steps 4 through 7 for any remaining cells Attach your cold water supply piping to the cold water basin suction connection in accordance with drawing instructions and utilizing gaskets provided by Marley Do not support your pipe from the tower or outlet connection Z Caution 10 support it exter
23. n Seasonal Shutdown Instructions When the system is to be shut down for an extended period of time it is recommended that the entire system cooling tower system piping heat exchangers etc be drained Leave the basin drains open During shutdown clean the tower see Warning page 18 and make any necessary repairs Pay particular attention to mechanical equipment supports and coupling or drive shafts Following each year s shutdown and cleaning inspect the tower s metal surfaces for evidence of the need to apply a protective coating Do not misinterpret grime and transient rust from the piping system as a need to have the tower painted If relatively bright metal can be exposed by cleaning consider that the galvanizing has remained effective Unless there is evidence of a generalized failure of the galvanizing localized touch up should be all that is required To the extent that the galvanizing zinc coating still exists paint will not adhere to it readily Contact the manufacturer of the coating you intend to use for instructions A Caution Maintenance Tower framework Check structural bolted connections and tighten as required Fans Check fan assembly bolting and tighten as required Use torque settings prescribed on the fan nameplate Electric motors Clean and lubricate motor at close of each operating season refer to motor manufacturer s recommendations Check motor anchor bolts and tighten as r
24. nally Normally one of the following three outlet arrangements is provided Side suction connection This is a factory installed galvanized pipe nipple extending horizontally from the side of the cold water basin It is both beveled for welding and grooved for a mechanical coupling If a weld connection is used it is recommended that the weld area be protected against corrosion Cold galvanizing is suggested applied according to the manufacturer s instructions Bottom outlet connection This is a factory installed screened circular opening in the cold water basin floor of one or more cells An appropriately sized circular opening has been drilled to accept a 125 ANSI B16 1 flat face flange connection Depressed sump connection Unless otherwise specified sumps are manufactured of heavy duty FRP fiber reinforced polyester construction Because of their size they are attached upside down in the basin to prevent damage in shipment They must be inserted into the square opening prepared in the floor of the cold water basin of one or more cells sealed against leakage and attached by machine bolts according to the installation drawing included An appropriately sized circular opening in the vertical face of the sump has been drilled to accept a 125 ANSI B16 1 flat face flange connection Attach makeup water supply piping to appropriately sized float valve connection located in cold water basin side wall Install the drain and ov
25. ncentrations 1 5X 2 5X 3 0X 4 0X 5 F 2 78 C 78 38 25 18 11 10 F 5 56 C 1 58 78 51 38 25 15 F 8 33 C 2 38 1 18 78 58 38 20 F 11 11 C 3 18 1 58 1 05 78 51 25 F 13 89 C 3 98 1 98 1 32 98 64 Cooling Range Multipliers are based on drift of 0 02 of the circulating water rate Range Difference between hot water temperature coming to tower and cold water temperature leaving tower EXAMPLE 700 GPM 44 2 L s circulating rate 18 F 10 C cooling range To maintain 4 concentrations the required blowdown is 0 458 or 00458 times 700 GPM 44 2 L s which is 3 2 GPM 0 2 L s If tower is operated at 4 concentrations circulating water will contain four times as much dissolved solid as the makeup water assuming none of the solids form scale or are otherwise removed from the system When water treatment chemicals are added they should not be introduced into the circulating water system via the cold water basin of the cooling tower Water velocities are lowest at that point which results in inadequate mixing Schedule of Tower Maintenance Some maintenance procedures may require maintenance personnel to enter the tower Each cased face of the tower has a door for access to the interior of the tower The NC1200 and NC2200 have a 30 wide by 33 high door All other models have a 30 wide by 48 high door The optional fan deck ladder is designed an
26. nto place according to the instructions on the label Hoisting clips are provided for ease of unloading and positioning tower For overhead lifts or where additional safety is required safety slings shouldalso be placed under the tower Under no circumstances should you combine the top and bottom modules of modular models and attempt to hoist them at the same time by utilizing the hoisting clips alone A Note A Note Installation Tower Installation These installation instructions are intended to help you prepare before your tower arrives If discrepancies exist between these instructions and those shipped with the tower the instructions shipped with the tower will govern 1 Prior to placement of the tower confirm that the supporting platform is level and thatthe anchor bolt holes are correctly located in accordance with Marley drawings Place tower or bottom module of NC8200 NC9200 and NCC200 models on your prepared supports aligning anchor bolt holes with those in your supporting steel Make sure that the orientation agrees with your intended piping arrangement Attach tower to supporting steel with four 5 8 16 mm diameter bolts and flat washers by others Position flat washers between the bolt head and the tower basin flange NC8200 NC9200 and NCC200 models only Clean any debris from the underside of the top module fill skid and beams and from the top of the bottom module before hoisting into place P
27. off the water flow will increase in the vicinity of the louvers and reduce the ice buildup 3 Under extended extreme cold conditions it may be necessary to operate the fan in reverse This forces warm air out through the louvers melting any accumulated ice adequate heat load must be available Reversal may be at either full or half speed however Marley recommends reversal at half soeed Reverse operation of the fan should be used sparingly and should only be used to control ice not to prevent it Reverse fan operation should not need to exceed 1 or 2 minutes Monitoring is required to determine the time required to melt accumulated ice Reverse operation of fans for prolonged periods during subfreezing weather can cause severe damage to fans and fan cylinders Ice can accumulate inside fan cylinders at fan blade plane of rotation and fan blade tips will eventually strike this ring of ice damaging the fan blades or cylinder Ice can also accumulate on fan blades and be IB 15 Z Caution 16 Operation thrown off damaging fan cylinder or blades Allow a minimum of 10 minute delay between reverse operation and forward operation during subfreezing weather to permit ice to dissipate from fan blades and fan cylinders See Fan Drive Caution note on page 11 for fan speed change and reversing precautions 4 With no heat load on the circulating water icing cannot be controlled effectively by air control during freezing weather T
28. owers must not be operated with reduced water rate and or no heat load during freezing weather f the circulating water system cannot be shut down water returning from the process should be made to bypass the tower If a bypass is used all water must be bypassed without modulation If the water bypass is directly into the tower s cold water basin its design must be approved by Marley Engineers Intermittent Wintertime Operation If periods of shutdown nights weekends etc occur during freezing weather measures must be taken to prevent the water in the cold water basin and all exposed pipework from freezing Several methods are used to combat this including automatic basin heater systems available from Marley Unless some means of freeze prevention is incorporated into your system the tower basin and exposed pipework should be drained at the beginning of each wintertime shutdown period It is recommended that you discuss your freeze prevention options with your local Marley sales engineer A Note Maintenance Water Treatment and Blowdown Maintaining Water Quality The steel used in NC Series towers has been galvanized with a heavy zinc coating averaging 2 0 mils in thickness NC Diamond Series towers are stainless steel Other materials used PVC fill drift eliminators and louvers aluminum fans cast iron Geareducer etc are selected to offer maximum service life in a normal cooling tower environment define
29. perature then becomes too warm for your process the motor can be restarted When operating in this mode care must be taken not to exceed a total A Caution acceleration time of 30 seconds per hour Fan cycling limits From a dead stop determine the number of seconds it takes the fan to arrive at full speed Divide this number into 30 to determine the allowable number of starts per hour Considering the normal fan and motor sizes utilized on NC Series towers anticipate that approximately 4 to 5 starts per hour are allowable If your tower is equipped with a two speed motor you will enjoy greater opportunity for temperature control When the water temperature becomes too cold switching the fan to half speed will cause the cold water temperature to rise stabilizing at a temperature a few degrees higher than before With a further reduction in water temperature the 13 A Note 14 Operation fan may be cycled alternately from half speed to off subject to the same constraint of 30 seconds of allowable acceleration time per hour as outlined above If your tower consists of two or more cells cycling of motors may be shared between cells increasing your steps of operation accordingly For greater insight on cold water temperature control please read Cooling Tower Energy and its Management Technical Report H 001 A available from your Marley sales engineer Wintertime Operation The Marley fill system used in NC S
30. rating temperature of the motor as well as the sight and sound of all components as a whole Check for Geareducer oil leaks Check the Geareducer as well as any optional oil lines to external oil dipstick sight glass Inspect louvers and remove any debris which may have accumulated Observe operation of the float valve Depress the operating lever to make sure that the valve is operating freely Inspect the suction screen for plugging Remove any debris that may have accumulated Check for any buildup of silt on the floor of the cold water basin Mentally make note of the amount if any so future inspections will enable you to determine the rate at which it is forming Semi Annually Relubricate motor according to the manufacturer s instructions See instructions on page 20 for towers with the motor located outside the plenum A Note A Warning Maintenance Check Geareducer oil level Shut down the unit and allow 5 minutes for the oil level to stabilize Add oil if required Check to see that all bolts are tight in the fan and mechanical equipment region including the fan cylinder and fan guard Use torque settings prescribed on the fan nameplate Visually inspect the drift eliminators Remove any accumulated debris or scale If basin silt level is significant drain the basin and clean it out Refer to Cooling Tower Cleaning section on page 18 Geareducer models used on NC cooling towers are designed for 5 year oil ch
31. s have not proved capable of withstanding the harsh environment of a cooling tower nor do they contribute their share to the thermal capability and operating characteristics intended 23 24 Maintenance Acomplete stock of a parts and components is maintained at one or more of the various Marley plants In cases of emergency they can normally be shipped within 24 hours by air freight if necessary However you would obviously benefit from anticipating your need in advance thus avoiding the cost of special handling Be sure to mention your tower serial number from the tower nameplate when ordering parts Periodic maintenance You may wish to contract with Marley for regularly scheduled visits for the purpose of inspecting and reporting your tower s condition to make recommendations intended to prevent emergencies and to perform maintenance considered outside the norm This service is not intended to replace the important function performed by your maintenance staff Their attention assures the tower s routine operating performance and is invaluable However Marley recognizes that the unusual manner in which a cooling tower performs its function as well as the unique forces which act upon it may be considerations which occasionally require the services of an expert technician Additional Information Increased load requirements Series NC towers are designed such that cells of either equal or unequal capacit
32. side suction connection vent accumulated air from the top of the suction hood by removing one or both tap screws provided at that location Replace these tap screws when venting is complete On certain models the top of the suction hood for 14 356 mm diameter side suctions is 1 1 4 32 mm above the top of the overflow In those situations it is necessary to block the overflow and continue filling the basin to the level where the aforementioned tap screws are submerged before venting 3 Completely open all hot water flow control valves Start your pump s and observe system operation Since the water system external to the tower will have been filled only to the level achieved in the cold water basin a certain amount of pump down of the basin water level will occur before water completes the circuit and begins to fall from the fill The amount of initial pbump down may be insufficient to cause the float valve to open However you can check its operation by pressing down on the operating lever to which the stem of the float valve is attached Some trial and error adjustment of the float valve may be required to balance the makeup water with tower operation Ideally the float valve setting will be such that no water is wasted through the overflow at pump shutdown However the water level after pump start up must be deep enough to assure positive pump suction 10 Operation 4 If the tower is equipped with flow contro
33. ss ice of amushy consistency can be tolerated but routine periodic observation is advisable Z Caution A Warning Operation If the minimum allowable cold water temperature is established at or near maximum heat load it should be safe forall operating conditions However if established at reduced load increased heat loads may reintroduce the potential for icing Having established the minimum allowable cold water temperature maintaining that temperature can be accomplished by fan manipulation as outlined in Item 4 under Tower Operation However in towers of more than one cell where fans are manipulated sequentially please realize that the water temperature will be significantly lower in the cell or cells operating at the highest fan speed than the net cold water temperature produced by the entire tower would indicate Wintertime operation of multicell towers at low cold water temperature levels requires that the operator be especially watchful 2 As cold air enters the louvers it causes the water flowing over the fill to be drawn inward toward the center of the tower Thus under fan operation the louvers and lower periphery of the tower structure remain partly dry seeing only random splashing from within the tower plus normal atmospheric moisture from the entering air Such lightly wetted areas are most subject to freezing Therefore if excessive ice forms on the louvers stop the fan for a few minutes With the fan
34. tative See Tower Operation Overpumping Reduce water flow rate over tower to design conditions Tower starved for air Check motor current and voltage to be sure of correct contract horsepower Re pitch fan blades if necessary Clean louvers fill and eliminators Check to see if nearby structures or enclosing walls are obstructing normal airflow to tower Discuss remedy with Marley representative Distribution basins overflowing Reduce water flow rate over tower to design conditions Be sure hot water basin nozzles are in place and not plugged Excessive Drift Exiting Tower Faulty drift elimination Check to see that integral fill louvers and eliminators are clean free of debris and installed correctly If drift eliminators are separate from fill make sure they are correctly installed in place Clean if necessary Replace damaged or worn out components 27 Maintenance Schedule Service Monthly Startup Shutdown Semi annually Inspect General Condition and Operation x x Observe Operation of Motor Coupling Geareducer and Fan Makeup Valve Inspect and Clean as Necessary PVC Air Inlet Louvers PVC Drift Eliminators Cold Water Basin and Outlet Hot Water Basins Fan Motor Exterior Check Cold Water Basin Level Blowdown adjust as required Check Geareducer for Oil Leaks Proper Oil Level Loose Bolts or Oil Plug
35. tructure of your NC Series consists primarily of galvanized steel therefore your water treatment program must be compatible with zinc In working with your water treatment supplier it is important that you recognize the potential effects on zinc of the specific treatment program you choose 17 A Warning 18 Maintenance Cooling Tower Cleaning Any evaporative type cooling tower must be thoroughly cleaned on aregular basis to minimize the growth of bacteria including Legionella Pneumophila to avoid the risk of sickness or death Service personnel must wear proper personal protective equipment Do NOT attempt any service unless the fan motor is locked out Operators of evaporative cooling equipment such as water cooling towers should follow maintenance programs which will reduce to an absolute minimum the opportunity for bacteriological contamination Public Health Service officials have recommended that good housekeeping procedures be followed such as regular inspections for concentrations of dirt scale and algae periodic flushing and cleaning and the following of a complete water treatment program including biocidal treatment The visual inspection should take place at least once a week during the operating season The periodic flushing and cleaning should be done before and after each cooling season but in any event atleast twice a year The louvers drift eliminators and easily accessible fill surfaces should be
36. ual must be held at 4 to 5 mg L ppm for six hours measurable with standard commercial water test kits If the cooling tower has been in operation and then shut down for a duration of time and not drained perform one of the two previous biocidal treatment programs directly to the cooling water storage vessel cooling tower sump drain down tank etc without circulating stagnant water over the cooling tower fill or operating the cooling tower fan After biocidal pretreatment has been successfully completed cooling water may be circulated over the tower fill with the fan off When biocidal treatment has been maintained at a satisfactory level for at least six hours the fan may be turned on and the system returned to service Resume the standard water treatment program including biocidal treatment A Warning A Warning A Caution Operation Mechanical Equipment Always shut off electrical power to the tower fan motor prior to performing any maintenance on the tower Any electrical switches should be locked out and tagged out to prevent others from turning the power back on 1 Check oil level in accordance with the operating instructions for the Geareducer Although Geareducer was filled to the proper level at the factory tipping during shipment and hoisting may have caused some loss of oil If oil is required fill Geareducer to the proper level with approved lubricant See Geareducer Manual Check oil level at Gearedu
37. ubleshooting sc ccs ceceitnae cnn e a eee At ae ae atte 26 The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk levels or to important information concerning the life of the product Indicates presence of a hazard which can cause severe personal injury death or substantial property damage if ignored Indicates presence of a hazard which will or can cause personal injury or property damage if ignored Indicates special instructions on installation operation or maintenance which are important but not related to personal injury hazards A Warning Preparation The Marley NC Series cooling tower purchased for this installation represents the current state of the art in crossflow induced draft cooling tower design Thermally and operationally it is the most efficient cooling tower of its class These instructions as well as those offered separately on motors fans Geareducers couplings drive shafts float valves etc are intended to assure that the tower serves you properly for the maximum possible time Since product warrantability may well depend upon your actions please read these instructions thoroughly prior to operation If you have questions about the operation and or maintenance of this tower and you don t find the answers in this manual please contact your Marley sales engineer When writing for information or when ordering parts please m
38. y can be added in the future This allows you to compensate for the load increases that normally occur with the replacement or addition of production equipment and still retain continuity with respect to your cooling tower system Tower rebuilding Marley routinely rebuilds and upgrades cooling towers of all materials and manufacture If your tower ever reaches the limit of its service life we recommend that you investigate the cost of rebuilding before you routinely order a new replacement tower Each NC tower includes a document package containing general orientation drawings a Field Installation Manual and tower component manuals These documents contain important information relating to safe installation and operation of the cooling tower Field installation is always required for fan guards piping inlets and piping outlets Some optional accessories such as valves handrails ladders and safety cages may also require field installation If installation details are not covered in the Field Installation Manual a separate installation drawing for each purchased option is included in the document package If you have purchased an option and can t find the appropriate installation drawing contact your local Marley office or representative before proceeding In addition to these specific documents Marley publishes numerous technical reports including more detailed information on a variety of cooling tower operation and service topics Your
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