background image

10   

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:

  The cooling tower establishes only the cold water temperature attain-

able 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, an 11°C reduction in wet-
bulb may result in only an 8°C reduction in cold water temperature.

3.  Water Flow Rate  Increasing the water flow rate (m

3

/hr) will cause a 

slight elevation in cold water temperature, while reducing the water flow 
rate will cause the cold water temperature to lower slightly. However, 
at a given heat load (see formula above), m

3

/hr reductions also cause 

an increase in the incoming hot water temperature. Use care to prevent 
the hot water from exceeding 46°C, in order to prevent damage to the 
tower components.

4.  Airflow Rate  Reducing airflow 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 temperature then 
becomes too warm for your process, the motor can be restarted.

operation

Range – °F    =

Heat Load (Btu/hr)

GPM  x  500

or — in SI units

Range – °C

    =

Heat Load (kW)

Water Flow (m

3

/hr)  x  1.162

Summary of Contents for NC fiberglass

Page 1: ...NC fiberglass cooling tower INSTALLATION OPERATION MAINTENANCE uk_Z0702489_D ISSUED 8 2018 READ AND UNDERSTAND THIS MANUAL PRIOR TO OPERATING OR SERVICING THIS PRODUCT user manual ...

Page 2: ...wn Instructions 19 Prolonged Shutdown 19 Maintenance Schedule 20 Additional Services 21 Troubleshooting 22 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 Note Indicates presence of a hazard which can cause severe personal injury death or substantial prope...

Page 3: ...ut the operation and or maintenance of this cool ing tower and you don t find the answers in this manual please contact your Marley sales representative When writing for information or when ordering parts please include the serial number shown on the cooling tower nameplate Safety First The location and orientation of the cooling tower can affect the safety of those responsible for installing oper...

Page 4: ...rchitect to certify that the location of the tower is in compliance with applicable air pollution fire and clean air codes Tower Assembly YourMarleysalesengineerisabletoprovideforthetowerassemblybyMarley s construction division or through a qualified subcontractor Our subcontrac tors provide safe efficient assembly which complies with all requirements for warranty protection of your tower by SPX C...

Page 5: ...ng tower commissioning when the tower is dry and the ambient air temperature is cool Do not start the motor more than four to five times per hour Short cy cling the tower will cause fuses breakers or O L s to operate and will decrease motor life When using a two speed starter Motor rotation must be the same at slow speed and high speed Single winding motor requires a starter with a shorting contac...

Page 6: ...when the cooling requirement can be satisfied at reduced speeds To benefit from these advantages it is important that the drive be installed correctly Marley supplies VFD and VFD controls specifically designed for our cooling products If you have purchased a Marley VFD and or controls package please follow the instructions in the User Manual for that system Most VFD problems can be avoided by purc...

Page 7: ... from below If rotation is backwards shut off the fan and reverse two of the three primary leads supplying power to the motor If tower is equipped with a two speed motor check for proper rota tion at both speeds Check also to see that starter 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 purpos...

Page 8: ...ater basin entire hot water basin and hot water inlet Make sure that cold water suction screens are clear and properly installed 4 For NC8401 thru NC8405 fill the water system to an approximate depth of 178mm in the depressed section of the cold water basin For NC8407 thru NC8414 fill the water system to an approximate depth of 203mm in the depressed section of the cold water basin This is the rec...

Page 9: ...ium hypochlorite to a level of 4 to 5 mg L free chlorine residual at a pH of 7 0 to 7 6 The chlorine residual must be held at 4 to 5 mg L for six hours measurable with standard com mercial 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 stor...

Page 10: ...same extent as the wet bulb For example an 11 C reduction in wet bulb may result in only an 8 C reduction in cold water temperature 3 Water Flow Rate Increasing the water flow rate m3 hr will cause a slightelevationincoldwatertemperature whilereducingthewaterflow rate will cause the cold water temperature to lower slightly However at a given heat load see formula above m3 hr reductions also cause ...

Page 11: ... Marley Technical Report H 001 Cooling Tower Energy and its Management available from your Marley sales representative or you can download a copy from Marley s website at spxcooling com Freezing Weather Operation During operation in subfreezing weather the opportunity exists for ice to form in the colder regions of the tower Your primary concern is to prevent the formation of destructive ice on th...

Page 12: ... as outlined in Item 4 under Tower Operation on page 10 However in towers of more than one cell the limiting temperature established applies to the water temperature of the cell or cells operating at the highest fan speed not necessarily the net cold water temperature produced by the entire tower 2 As cold air enters the louvers it causes the falling water to be drawn inward toward the center of t...

Page 13: ...reezing Several methods are used to combat this Consult your Marley sales representative for more information 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 representative C...

Page 14: ... with zinc In working with your water treatment supplier it is impor tant that you recognize the potential effects on zinc of the specific treatment program you choose Blowdown Acoolingtowercoolswaterbycontinuouslycausingaportionofittoevaporate 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 t...

Page 15: ...nagementplan WMP andimplementationofmaintenance proceduresareessentialtopreventthepresence disseminationand amplification of Legionella bacteria and other waterborne contami nants throughout premise plumbing Before operating the cooling tower the water management plan and maintenance procedures must be in place and regularly practiced In addition the following steps are recommended Do NOT attempt ...

Page 16: ... contact your Marley sales represen tative For help identifying the sales representative in your area visit spxcooling com replocator Schedule of Tower Maintenance Included with this instruction packet are separate User Manuals on each major operating component of the tower and it is recommended that you read them thoroughly Where discrepancies may exist the separate User Manuals will take precede...

Page 17: ...ate method for tensioning V belts Check with you local belt supplier Sheave Alignment The motor sheave is to be positioned as close as possible to the motor in order to minimize torque on the motor bushings The motor and fan sheaves may have grooves that are not used The bot tom surface of the motor and fan sheaves must be aligned within 3mm of each other and level within 3mm in 300mm in order to ...

Page 18: ... may have accumulated Check for any buildup of silt on the floor of the cold water basin Mentally note the amount if any so future inspections will enable you to determine the rate at which it is forming Every 3 months Lubricate fan shaft bearings While rotating equipment by hand grease the bearings with lithium based grease until a bead forms around the seals Mobil SHC 460 grease is recommended S...

Page 19: ...en as required Fan Check fan assembly bolting and tighten as required Use torque settings prescribed on the fan nameplate Refer to fan user manual Fan Motor Clean and lubricate motor if required at close of each operating season Refer to motor manufacturer s recommendations Does not apply to motorswithsealedbearings Checkmotoranchorboltsandtightenasrequired Do not start motor before determining th...

Page 20: ...x element for unusual wear x x Lube lines if equipped Check for oil leaks in hoses or fittings x R x Belt drive if equipped Fan shaft bearing lubrication every 3 mo every 3 months every 3 months Check and tighten support fasteners x Check shaft sheave and belt alignment x Check belt tension and condition x x Check sheave bushing fastener torque x Fan Check and tighten blade and hub fasteners x Che...

Page 21: ...complete stock of all 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 par...

Page 22: ...cket fits or bearing Rotor unbalance Rebalance Cooling fan hitting end bell guard Reinstall or replace fan Motor runs hot Wrong voltage or unbalanced voltage Check voltage and current of all three lines against nameplate values Overload Check fan blade pitch See Fan User Manual Check for drag in fan drivetrain as from damaged bearings Wrong motor RPM Check nameplate against power supply Check RPM ...

Page 23: ... shaft with dial indicator Replace if necessary Fan noise Blade rubbing inside of fan cylinder Adjust cylinder to provide blade tip clearance Loose bolts in blade clamps Check and tighten if necessary Scale or foreign substance in circulating water system Insufficient blowdown See Water Treatment section of this manual Water treatment deficiency Consult competent water treating specialist See Wate...

Page 24: ... RESERVED In the interest of technological progress all products are subject to design and or material change without notice SPX COOLING TECHNOLOGIES UK LTD 3 KNIGHTSBRIDGE PARK WORCESTER WR4 9FA UK 44 1905 750 270 ct fap emea spx com spxcooling com NC Fiberglass US E R MAN UAL ...

Reviews: