CN:01-96

TAHVIEH CO.

CoolingTowersModel VX

English/Metric Measure

TAHVIEH

VX COOLING TOWERS

VXWater is one of our most preciousresources and consumption hasreached unprecedented levels . Coolingtowers recycle cooling water, so it canbe used over and over again . Recyclingreduces water consumption by 95%when compared to out-dated((once-through)) systems, thus, reducing waterand sewage costs .

EVAPORATIVE COOLING =WATER CONSERVATION

The water from the heat source isdistributed over the wet deck surfaceby spray nozzles . Air is simultaneouslyblown upward over the wet decksurface, causing a small portion of thewater to evaporate . This evaporationremoves heat from the remainingwater . The cooled water is collectedthe tower sump and returned to theheat source.

PRINCIPLE OF OPERATION

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COOLING TOWERS

...for cooling water inair conditioning, refrigeration,and industrial process systems

VX Cooling Towers extend the provenadvantages of V-Line with a broaderchoice of sizes to closely match thecapacity, space , and applicationrequirements of virtually any project.All units are designed to ensure quietoperation, dependable performance,long life, and ease of maintenance.

The compactness of the V-pan and thestatic pressure capabili ty of thecentrifugal fans make VX CoolingTowers the logical choice for indoorinstallations of restricted outdoorenclosures. Single-fan-side design anda variety of width and lengthcombinations provide alternativeconfigurations to fit the requiredcapacity in the available space.

Because the recessed centrifugal fansare inherently quiet, Vx CoolingTowers are preferred whenever lowsound levels are desired. Soundattenuation accessories manufacturedby TAHVIEH are available for projectsrequr ing very quie t opera t ion.

A choice of materials of constructionincluding two wet deck surface optionsand TAHVIEH engineered accessoriesmean the VX Cooling Tower can meet

vi r tual ly every appl icat ion andinstallation need including completefireproof construction for P.V.C. wetdeck surface and reliable year-roundoperation .

Product life is extended andmaintenance costs are minimized bythe blow-through design which placesall moving parts in the dry enteringairstream. VX Cooling towers areconstructed of heavy gauge,galvanized steel with a provencorrosion protection finish significantlybe t te r than ga lvaniz ing a lone.

Ease of maintenance is provided bythe self-cleaning V-pan and largeorifice spray nozzles. All rotating partsare located at the base of the unit foreasy access and main tenance.

All units are factory-assembled foruniform quality of construction andperformance with major componentshaving been designed, tested, andmanufactured by TAHVIEH.

C O N T E N T S

VX Advantages / 4Construction Details / 9Selection / 10Engineering Data / 14Application / 18Optional Accessory Equipment / 20Optional Materials / 22Support / 23Engineering Specif icat ion / 24

5

VX Advantages for the Designer

QUIET OPERATION

LOCATION VERSATILITYCompact Outdoor Installation

The ability to locate the compact VX Cooling Towers intight locations allows designers of cooling systems tobetter utilize available space . Smaller , less costlyenclosures can be used and units can be placed in narrowsetbacks or close to solid walls. Optional dischargehoods can be used to further reduce space requirments.

Compact Indoor Installation

VX Cooling Towers with centrifugal fans are ideally suitedfor indoor installation which are often desirable forfreeze protection, noise abatement, space limitation, orallows inlet ducting and uses a minimum amount ofvaluable indoor space .

Concern about noise pollution has made it necessary toconsider sound when select ing equipment . Manygovernmental bodies have enacted strict noise ordinancesthat affect the sound generated by mechanical equipment.TAHVIEH has the abili ty to solve sound problems.

Quiet Design

VX Cooling Towers are particularly suited for noise sensitiveinstallations. The use of centrifugal fans and the V designcreating a recessed fan position enables the VX CoolingTowers to achieve superior acoustical performance.

Directional Advantage

In situation where one direction is particularly noisesensitive, the single-fan-side design of VX Cooling Towersallows the quieter back-panel side to be directed towards thisnoise sensitive direction. In many instances, this procedureeliminates the need for additional acoustical treatment.

Sound Attenuation Available

When even quieter operation is desired , the VX CoolingTowers can be supplied with packaged sound attenuators toreduce sound levels further. These attenuators are designedand built by TAHVIEH specifically for use on this equipment.

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The versatile VX Cooling Tower is produced in a broadrange of capacities , with small capacity incrementsto permit close matching of unit size to design load.

A variety of width and length combinations providesalternative configurations to fit the available space.

Single fan design permits basic modules to be

Designed for Cold Weather

TAHVIEH VX Cooling Towers are ideally suited foryear-round operation. Since the below-through design placesthe fans, motors and drives in the dry entering airstream,these moving parts are protected from moisturecondensation and fan icing. The counterflow design providesmore even cooling and has fewer potential icing problemsthan crossflow designs.

maintaining a set leaving water temperature. Minimumyear-round energy consumption is an additional benefitsince less fan horsepower is required as the dampersmodulate from the full open position.

Fan CyclingSome installations do not require close control of thecooling water. VX Cooling Towers with fan cycling may besatisfactory for those systems . Additional steps ofcapacity control can be obtained by providing these unitswith two-speed motors.

BROAD RANGE OF SIZES

combined back-to-back and end-to-end for standardarrangements up to large 21100 kW; thusmaking the design of large capacity installations easier.

With a total of 65 models to choose from, the VX-Lineoffers the widest selection of centrifugal fan coolingtowers in the industry to meet virtually every installationand application need.

Accessories for Winter Operation

Standard accessories are available to provide protectionagainst icing conditions. They include sump water heaters,dampers and electric water level control packages. Since notall of these accessories are required for every cold weatherapplication. TAHVIEH should be consulted for the year-roundoperating needs of a particular installation.

YEAR-ROUND OPERATION

Modulating DampersMany installations requirecloser temperature control thancan be obtained from thecycling of the unit fans alone.On these systems, the VX Cool-ing Towers can be furnishedwith modulating capacity con-trol dampers. These dampersmatch the capacity of coolingtower to the system load while

CLOSE TEMPERATURE CONTROL (OPTIONAL)

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VX Advantages for the Owner

Single Fan Side Saves CostHaving a single fan side design means fewer motor starters to install andwire, fewer motors to maintain, and fewer accessories to purchase. This fanarrangement also saves cost by enalbing the units to fit close to walls or innarrow set-backs to allow more profitable use of premium space.

Lower Rigging CostRigging costs are greatly reduced with the modular design of the VX CoolingTowers. The fan sections are built into the pan with the motors and drivesfactory-installed and aligned eliminating the need for handling these items inthe field. As a result, rigging consists only of placing the fan/pan section inplace and mounting the heat transfer section on top of it .

Few Moving PartsLess maintenance is an inherent benefit of TAHVIEH`s singlefan side design because there are a minimum number offans, bearings, motors, and drives.

Easy AccessAll moving parts are located near the base of the unitwithin easy reach for cleaning, lubrication, or adjustment.Belt adjustment on VX units is accomplished by a singlethreaded bolt and nut assembly accessible from outsidethe fan assembly the interior of the unit is easilyaccessible through leakproof . Man-size access doors foradjusting the float valve, cleaning the strainer, or flushingthe sump.

Trouble-Free Water DistributionThe water distribution system employs large orificeplastic nozzles which greatly reduce the potential forclogging, so thermal performance is more consistentbetween maintenance periods. When nozzles must becleaned, the large orifices can be cleaned in place, butare grommeted to easy removal, i f necessary.

Easy To CleanLarge pan space simplifies cleaning the unit interior-another inherent benefit of single fan side design.

The cylindrical pan strainer provides a large effective areain a single strong. But lightweight, piece whichmaintenance personnel can easily remove for cleaning.

LOW INSTALLED COST

EASY MAINTENANCE

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The pan section of TAHVIEH VXCooling Towers is actually acombination of a pan and fanarrangement consisting of a V-shapedsump, with blow-through centrifugal fansmounted on one side underneath thesloping pan. The entire assembly isconstructed of heavy gauge, galvanizedsteel.

1. ACCESSLeakproof, circular access doors arefurnished to provide convenient accessto the interior of the pan/fan sections forinspection and adjustment of the floatvalve, cleaning the lift-out strainers, andflushing the sump.

2. STRAINERA strainer assembly of anti-vortexingdesign is standard on all VX-CoolingTowers. Large area lift-out strainerscreens are provided to avoid the needfor frequent servicing while the perforatedstrainer surface washes clean quickly,when service is required. Theantivortexing baffle is specially designedto preclude air entrainment.

3. MOTORS AND DRIVESDrip-proof fan motors are furnished asstandard. In addition to being suitable foroutdoor service, the motors are shelteredfrom the weather by their location underthe sloping pan side. V-belt drives aredesigned for not less than 150%of motor nameplate power rating. Thebelts are easily adjusted by means of athreaded bolt and nut arrangement.

4. FAN SHAFT& BEARINGSAll models have a solid steel fan shaftsupported on each end by a ballbearing. Where intermediate bearingsare required , self-aligning , oil lubricated,sleeve type bearings with split, cast iron,pillow-block housings are furnished .

5. FANSThe forwardly curved centrifugal fansare statically and dynamically balanced.They are mounted in fan housings.

6. HEAVY DUTY CONSTRUCTIONThe pan/fan section consists of heavygauge , hot-dipped galvanized panels.This heavy duty construction provides the

strength and rigidity required for lastingtrouble-free operation. All pan/fan sectionpanels are formed for maximum strength.

7. PROTECTION FOR MOVING PARTSAll moving parts are protected by inletscreens on the front of the fan housingsand by solid panels on the ends of theunit fan section(s). Screens and panelsare easily removable for access to fans,bearings, motor and drives. Bottomscreens or a solid bottom panel areavailable as optional equipment if the unitinstallation requires this additionalprotection.

8. FAN DISCHARGE COWLSFan discharge cowls, mounted inside thesloping pan sides, are designed to recovernormal velocity pressure losses, providingincreased fan efficiency and lower energyconsumption.

9. WATER MAKE-UP VALVEThe base float valve on the water make-up connection is actuated by a largediameter plastic float. Water level iseasily adjusted by means of wing nuts onthe float rod.

Construction Details / Pan Section

PAN SECTION

Construction Details / casing Section

1. WATER DISTRIBUTION SYSTEMWater is distributed over the wet decksurface by a header and spraybranches. The branches are connectedto the main header by means of agrommet assembly so they can beindividually removed for flushing andcleaning . Large diameter, non-clog,pastic spray nozzles are oriented foroptimum water distribution over the wetdeck surface.the nozzles are held in place withsnap-in rubber grommets which premitquick removal for cleaning. A 8 mmtapping in the header facilitatesmounting of an external pressure gauge

CASING SECTION

to check water spray pressures

2. TAHVIEH WET DECK SURFACE*An efficient polyvinyl chloride (PVC) wetdeck surface manufactured by TAHVIEHis furnished as standard in VX CoolingTowers.The special configuration prividesmaximum contact between air and waterwith low air pressure drop to ensureefficient heat transfer while minimizingpower requirments. Optional wet decksurface materials are discussed onpage 22.

3. CASINGThe casing of the heat transfer sectionis constructed of heavy gauge,galvanized steel. All casing panels areformed for maximum strength anddie-punched to assure accurate matingof the casing section to the pan section.

4. ELIMINATORSThe eliminators are constructed ofP.V.C. assembled in easy to handlesections the eliminators lift aside foraccess to the spray tree and nozzles.

*Patent Pending

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Engineering dataModels VXT 10 to VXT 185

This brochure includes data current at the time of publication which should be reconfirmed at the time of purchase.

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Engineering dataModels N215 to VXT N535

This brochure includes data current at the time of publication which should be reconfirmed at the time of purchase.

15

This brochure includes data current at the time of publication which should be reconfirmed at the time of purchase.

Engineering data / Models VXT

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315 to VXT 4800

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Application

Satisfactory VX Cooling Tower performance is dependenton correct selection and proper attention to overallsystem design and installation . Some of the major designconsiderations are discussed below. For more detailedrecommendations, consult TAHVIEH.

LocationVX Cooling Towers must be located so there is anunimpeded supply of air to all fans. When units arelocated in enclosures or close to building walls, the top ofthe unit must be level with the top of adjacent walls. Thiswill, reduce the possibility of capacity reduction due torecirculation of the warm saturated discharge air backinto the fan intakes . On installations where the unitcannot be elevated to premit discharge above adjacentwall a discharge hood (see page 20) orduct should be provided to raise the dicharge openingeven with the top of the enclosure or adjacent wall.Additionally, each Cooling Tower should be located andpositioned to prevent the introduction of its discharge air intothe ventilation systems of the building on which the tower islocated and of adjacent buildings.

Indoor InstallationsMany indoor installations require the use of inlet and/ordischarge ductwork. Towers installed with inlet ductworkmust be ordered with solid bottom panels. Generally,intake ducts are used only on the smaller units while theequipment room is used as a plenum for the larger units.

Discharge ductwork will normally be required to carry thesaturated discharge air from the building.

Both intake and discharge ductwork must have accessdoors to allow servicing of the fan assembly, eliminators,and water distribution system. All ductwork should besymmetrical and designed to provide even air distributionacross the face of intakes and discharge openings.

Ducts must be designed for static pressure loss of 125 Paor less and fan motor sizes must be increased one size.

Wet Deck Surface CompatibilityThe maximum allowable entering water temperature for VXTower with PVC wet deck surface is 55 C.The PVC wet deck surface is compatible with the water foundin most cooling tower applications . However, for applicationswhich may require an alternative type of wet deck surfacematerial refer to the Optional Construction Section (page 22)where wet deck surface options are discussed. For the properchoice of wet deck surface contact TAHVIEH .

pipingPiping should be sized and installed in accordance withgood piping practice. In order to prevent overflowing ofthe tower basin and ensure satisfactory pump operationat start-up, all heat exchangers and as much tower pipingas possible should be installed below the operating levelof the tower. In addition , all piping should be supportedseparately from the unit through the use of pipe hangersor supports.

If more than one inlet connection is required , balancingvalves should be installed to properly balance flow toeach cooling tower cell. Shut-off valves are optional andtheir use is dictated by the necessity to isolate units forservicing. Maximum required spray pressure at the inletheader is 35 kPa.

When multiple towers (such as Models VXT-1260 throughVXT-4800) are used on a common system, equalizing linesshould be installed between the sumps of the separateunits to ensure a balanced water level in all units.

Capacity ControlMost cooling tower systems are subject to substantialchanges in load and/or ambient temperature conditionsduring the normal operating season. The capacity of VXCooling Towers varies greatly as the wet bulbtemperature changes. When a reasonably constantleaving water temperature is desired , some form ofcapacity control is required during periods of reducedload or low ambient temperature condit ions.

Fan cycling is the simplest method of capacity control onVX Cooling Towers and is often used on multiple unitinstallations. At above freezing ambient temperatureswhere close control of the water temperature leaving thetower is not essential, fan cycling affords an adequateand inexpensive method of temperature control.

The number of steps of capacity control can be doubledby using two speed fan motors in conjunction with fancycling . This is particularly useful on single fan motorunits. Two speed fan motors also provide additionalenergy savings when compared to simple fan cycling.

Where close control of the leaving water temperature isrequired or the unit is to operate at subfreezing ambienttemperatures, the recommended method of capacitycontrol is modulating capacity control dampers (SeeAccessories, page 20). Fan discharge dampers providemodulation of capacity by varying the airflow to matchthe tower capacity to the system heat load. End switches

18*Patent pending

on the damper motors shut off the fan motors when thedampers reach the minimum position. Damper controlalso provides operating savings since the fan power rating isreduced with reduced airflow.

Protection Against Pan Water FreezingAs lons as the VX Cooling Tower is in operation underload with capacity control dampers, the recirculatingcooling water will not freeze. However, when the tower isshut down, the pan water must be protected. An indoorauxiliary sump is the best means of avoiding pan waterfreezing in an idle tower. With this remote sump system,the pan water is always drained to the indoor sumpwhenever the recirculating water pump is stopped.

Where a remote sump is impractical because of towerlocation or space limitations, supplementary heat must besupplied to the pan water through the use of electricimmersion heaters, steam coils, or hot water coils (seeAccessories, page 20).

In addition, all exposed water piping and makeup linesthat do not drain at shutdown should be traced withelectric heater tape and insulated.

Water TreatmentAs water evaporates in a cooling tower, the dissolved solidsoriginally present in the water remain in the system. Theconcentration of dissolved solids increases rapidly and canreach unacceptable levels. In addition, airborne impuritiesand biological contaminants are often introduced into therecirculating water. If impurities and contaminants are noteffectively controlled, they can cause scaling, corrosion,sludge or biological fouling .

Accordingly, a water treatment program should be employedto control all potential contaminants. While in many casessimple bleed-off may be adequate for control of scale orcorrosion, it is insufficient to control biological contamina-tion and this subject must be addressed in any treatmentprogram. The treatment program must be compatible withgalvanized steel and the pH of the pan water must bemaintained between 6.5 and 8.5 .

Batch chemical feeding for scale and corrosion control is notrecommended since effective mixing may not be achieved inthe cooling tower sump.

For specific recommendations on water treatment contact acomponent water treatment supplier.

SOUNDAs society becomes more concerned about the quality ofits environment, sound is becoming an important consider-ation in the selection and location of mechanical equipment.There are basically three steps involved in evaluatingthe sound from a cooling tower to determine if it will beacceptable for the installation. These three steps are :establishing the sound criteria, estimating the sound levelsgenerated by the cooling tower, and comparing the soundcriteria to the generated sound levels.

Establishing the Sound Criteria- The system designerusually establishes the acceptable sound level for theproject based on his judgement , local code requirements,and the needs of the owner.

Sound Levels Generated By the Cooling Tower- TAHVIEHhas certified sound rating data available for all of itsproducts. These data is required to calculate sound levelsgenerated by the cooling tower . In addition, the designermust take into account the effects of the geometry of thetower to noise sensitive areas.

Comparing Sound Levels -The last step is compare theestablished noise criteria with the expected sound levels todetermine if the tower sound will be acceptable.

In the event that the cooling tower sound may be excessivefor the particular site conditions; packaged soundattenuation, barrier walls, or relocation of towers may beused to reduce or control the sound levels.

Application ChecklistShown below are items that should be checked before thedesign of a VX Cooling Tower installation is completed.

1. Correct Selection2. Location a. Outdoor b. Indoor3. Wet Deck Compatibility4. Piping a. Inlet b. Outlet c. Drain d. Make-up e. Overflow f. Support g. Equalizer5. Capacity Control6. Pan Water Freeze Protection7. Water Treatment8. Sound

Adequate precautions should be taken to safeguard theequipment and the premises from damage and the publicfrom possible injury as appropriate for the installationand location of these products.

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Optional Accessory Equipment

ELECTRIC WATER LEVEL CONTROLA factory-set electric water level control system can besubstituted for the standard mechanical makeup valve toprovide exceptionally accurate water level control. Nofield adjustment is necessary regardless of variations inthermal loads on the cooling tower or variations inmakeup water supply pressure. This system consists of aweather protected electric float switch with stillingchamber mounted on the pan/fan section and a solenoidvalve factory installed at the makeup water connection onthe unit. All wiring must be provided by others.

Because this accessory assures a constant water levelwithout adjustment, it is recommended for use on unitsthat will require year-round operation in a freezingclimate.

SOLID BOTTOM PANELSFactory-installed bottom panels are available. Their use isrequired when the intake air is ducted to the unit.

When a tower is specified for use with inlet ductwork, thesolid bottom panel pakage includes lubrication fittingsextended outside the fan section and the unit is furnishedwithout air inlet screens.

BOTTOM SCREENSAir inlet screens can be factory installed on the bottom ofthe cooling tower when location makes this additionalprotection desirable or necessary for safety or otherreasons.

PAN WATER HEATERSCooling Towers that will be exposed to below-freezing

ambient temperatures require protection to preventfreezing of the pan water when the cooling tower is idle.Heaters se lected to mainta in +4 C pan watertemperature afford a simple and inexpensive way ofproviding such protection. Factory-installed pan heatersof two types are available.

Electric Heaters - Electric immersion heaters are normallyfactory-installed in the cooling tower basin. The heatersare controlled by a thermostat with the sensing bulblocated in the pan water. A low water level control, alsoheater elements are fully submerged.

Immersion heaters should be interlocked with watercirculating pump to de-energize heaters whenever thecirculating pump is running.

Pan Coil - A steam coil or a hot water coil can be factoryinstalled in the cooling tower basin. The coil is constructedfrom galvanized steel pipe ready for piping to an externalsteam or hot water source.

Modulating capacity control dampers areavailable for all VX Cooling Towers and arerecommended when close control ofleaving water temperature is requiredand/or the tower will be operated undervarying loads at below-freezing ambienttemperatures. Capacity control thancan be obtained from the cycling of theunit fans alone.

Capacity control dampers consist of asingle airfoil type damper blade located

in the discharge of each fan housing. In this location, thedampers are protected from the cascading water in theunit, preventing corrosion of the damper linkage andblade icing at low ambient temperatures.

CAPACITY CONTROL DAMPERS

20

DISCHARGE HOODSBaltimore Aircoil offers a full line of standard dischargehoods for all VX Cooling Towers. These hoods aredesigned to increase the discharge air velocity to avoidrecirculation in extremely tight enclosures. They can beused to elevate the tower discharge above must be used whenhoods are provided.

ENGINEERED SOUND ATTENUATION SYSTEMSVX Cooling Tower installations will meet most sound levelcriteria without attenuation. For extremely noise sensitiveinstallations, factory-built sound attenuation systems areavailable for field mounting . The full line of sound attenuationsystems consists of two types of barrier attenuation to meethorizontal noise criteria and three types of air intake and airdischarge sound attenuators to meet both horizontal andvertical noise citeria. All engineered sound attenuationsystems are designed to allow easy access to all moving partsof the unit.

VIBRATION ISOLATORSTAHVIEH VX Cooling Towers operate with virtually no vibrationand generally do not require vibration isolation.

CONNECTIONSThe design of the VX tower allows for addit ionalconnections to be installed in the pan for equalizing,bypass, or optional suction location.

When the tower is specified for remote sump operation,the float valve and strainer are omitted and an oversizedoutlet is provided.

Connections can be provided as flanged, beveled-for-welding, or threaded depending on size and location.

EXPORT SHIPMENTSVX Cooling Towers can be prepared for export shipment ineither of two ways : minimum export crating acceptable tothe carr ier, or completely closed export boxing.

21

High Temperature

Optional Materials

WET DECK SURFACE

In application where temperatures may exceed 55 C, high temperature TAHVIEH wet deck surfacecan be provide

TAHVIEH WetDeck Surface

STAINLESS STEEL COOLING TOWERS

Water ContactWater contact stainless steel VX towers utilize 304 stainless steel in all areas ofthe tower which come in contact with water while the remainder of the unit is builtof hot-dip galvanized steel. This construction provides the corrosion resistanceof stainless steel where it is needed most at a lower cost than all stainlessconstruction.

The components made of stainless steel are : casing panels, discharge eliminators,V pan section panels, strainer assembly , fan discharge snout, and internalbaffles. Pan section components which are located in the dry entering air are madeof standard hot-dip galvanized steel protected.

All StainlessIn situations where the air moving equipment along with the water contactcomponents must be stainless steel, all 304 stainless VX construction can besupplied.

All components except the heat transfer section, fan motors, belts and sheavesare made of stainless steel when this type of construction is chosen.

For those installations where severe corrosion conditions exist and exceptionally long life is desired,TAHVIEH offers the VX Cooling Towers in stainless steel construction. VX Stainless Steel CoolingTowers can be built of stainless in water-touched areas only, or of complete stainless steelconstruction.

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The recommended support arrangement for TAHVIEH VXCooling Towers is two I beams running the full length ofthe unit . Besides providing support, the steel also servesto raise the unit above any solid foundation which mightrestrict air movement or prevent access to the bottom ofthe unit. The steel support beam must be located directlybeneath the unit and extend the full length of the pansection. Support beams and anchor bolts are to befurnished and installed by others.

BEAM SIZE AND LENGTHBeams size should be calculated inaccordance with accepted structuralpractice. Use 65 percent of theoperating weight as a uniform load oneach beam. The length of the beammust be at least equal to th elength ofthe pan. Refer to Engineering Datasection pages 14 to 17 for pandimensions.

Maximum permissible beam deflectionand center line distances between boltholes are tabulated below.

VIBRATION ISOLATORSIf vibration isolators are used, a rail orchannel must be provided between theun i t and the i so l a to r s t o p rov idecon t inuous un i t suppor t . Re fe r tov ibra t ion i so la tor drawings for thelength of the rails and mounting holelocations which may dif fer f rom thelength and the hole locations of theunit itself.

Support

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Engineering Specification forVX Cooling TowersCOOLING TOWER - Furnished and install, as shown on plans, .....factory-assembled cooling tower(s) of sectional, blow-through design.The tower(s) shall have centrifugal fan assemblies built completely into the panwith all moving parts factory-mounted and aligned. Tower(s) shall be internallybaffled to premit independent operation of the individual fan section assem-blies. Air entry shall be from one side only.All steel components shall be made from hot-dip galvanized steel, with alledges given a protective coat of zinc-rich compound. In addition, the finalzinc-chromatized aluminium finish shall be applied to the unit(s) after assem-bly to provide additional corrosion protection.

CAPACITY - The cooling tower(s) shall have the capacity to cool ...... I/sof ......... from ........... C to ........... C with ........... C entering air wet bulbtemperature. The tower(s) shall operate against .................. Pa External StaticPressure.

PAN/FAN SECTION - The combination pan/fan section shall consist of heavygauge hot-dip galvanized steel pan with centrifugal fans mounted beneath theslopping undersides of the pan . The fans and motors shall be located in the dryentering airstream to provide greater reliability and ease of maintenance.Standard pan accessories shall include circular access doors, large area lift-outhot-dip galvanized steel strainer with perforated openings sized smaller thanspray nozzle orifices, and brass make-up valve with large diameter plastic floatarranged for easy adjustment.

VXT MODELS - The forwardly curved centrifugal fans shall be statically anddynamically balanced. Fan housings shall have curved inlet rings for efficientair entry, and rectangular discharge cowls shall extend into the pan to increasefan efficiency and prevent water from entering the fans. Fans shall be mountedon a steel fan shaft supported by heavy-duty, self-aligning, relubricatablebearings with cast iron housings.

FAN MOTOR AND DRIVE - .......... kW, ........... rpm TEFC ball bearing fanmaotor(s) shall be suitable for outdoor service and operation on ........... volt,............. hertz, ............. phase electrical service. Each motor shall be mountedon an easily adjusted heavy-duty motor base located so the drive and motor arein a protective enclosure beneath the pan side.V-belt fan drive(s) shall be designed for not less than 150 % of motornameplate power rating. Drive(s) and all moving parts shall be protected byremovable hot-dip galvanized screens and panels.

SURFACE SECTION - The heat transfer casing section(s) shall be removablefrom the pan-fan section to facilitate rigging. Each section shall include theBACount*, PVC wet deck surface below a spray-type water distribution system,all encased by hot-dip galvanized steel panels with removable sectional elimina-tors at top. The wet deck surface shall consist of sheets of self-extinghuisingpolyvinyl chloride (PVC). a minimum of 0.4 mm thick.The surface shall be manufactured and performance tested by the cooling towermanufacturer to assure single source responsibility and control of the final product.

WATER DISTRIBUTION -Water shall be distributed evenly over the tower fillarea by a water distribution system consisting of header and spray branches ofof 19 mm x 8 mm. The branches and plastic spray nozzles shall be held in placecomplete branches for cleaning or flushing. The header shall include provisionsfor measuring spray pressure externally.

ELIMINATORS - Eliminators shall be constructed of hot-dip galvanized steeland be removable in easily handled sections. They shall have a minimum ofthree changes in air direction with a hooked leaving edge, and shall directdischarge air away from the fans.

UNIT SIZE - Overall dimensions shall not exceed approximately .......... mmx .............. mm with an overal height not exceeding approximately ............ mm.The operating weight shall not exceed ........... kg.The cooling tower shall be TAHVIEH MODEL ............ .

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