cATW Closed Circuit Cooler

Principle of Operation

The process fluid is circulated through the coil of the closed circuit cooler. Heat from the process fluid is dissipated through the coil tubes to the water cascading downward over the tubes. Simultaneously, air is drawn in through the air inlet louvers at the base of the cooler and travels upward over the coil opposite the water flow. A small portion of the water is evaporated which removes the heat. The warm moist air is drawn to the top of the closed circuit cooler by the fan and is discharged to the atmosphere. The remaining water falls to the sump at the bottom of the cooler where it is recirculated by the pump up through the water distribution system and back down over the coils.

Thermal-Pak II® Coil

EVAPCO's Thermal-Pak II® coils feature a patented design which assures maximum cooling capacity. The airflow through the coil is counter to the fluid flow, providing the most efficient heat transfer process. A special coil design is utilized to reduce the air pressure drop through the unit while maximizing tube surface area and increasing its heat transfer capabilities. The uniquely shaped tubes of the coil are staggered in the direction of airflow to obtain a high film coefficient.

The coils are manufactured from high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected to assure the material quality and then tested before being assembled into a coil. Finally, the assembled coil is pneumatically tested at 400 psig (2758 kPa) under water to ensure it is leak free.

To protect the coil against corrosion, it is placed in a heavy steel frame and then the entire assembly is dipped in molten zinc (hot-dip galvanized) at a temperature of approximately 800°F (427ºC).

Note: Closed circuit coolers should only be used on sealed, pressurized systems. Continual aeration of the water in an open system can cause corrosion inside the tubes of the cooler leading to premature failure.

Efficient Drift Eliminators

An extremely efficient drift eliminator system is standard on the cATW Closed Circuit Cooler. The system removes entrained water droplets from the air stream to limit the drift rate to less than 0.001% of the recirculating water rate. With a low drift rate, the cATW Closed Circuit Cooler saves valuable water and water treatment chemicals. The cATW Closed Circuit Cooler can be located in areas where minimum water carryover is critical, such as parking lots.

The drift eliminators are constructed of an inert polyvinyl chloride (PVC) plastic material which effectively eliminates corrosion of these vital components. They are assembled in sections to facilitate easy removal for inspection of the water distribution system.

Superior Air Inlet Louver and Screen Design

The air inlet louver screens on the cATW are constructed of corrosion-free PVC. They are a two pass design that minimizes splashout and reduces the potential for algae formation inside the cooler.

In single pass louver systems used by other manufacturers, circulating water droplets tend to splashout, especially when the fans are shut off. With the two pass louver system, the water droplets are captured on the inward sloping pass, minimizing splashout problems.

This unique louver design completely encloses the basin area. Direct sunlight is blocked from the water inside the cooler, thereby reducing the potential of algae formation. Water treatment and maintenance costs are substantially reduced.

While effectively containing the recirculating water and blocking sunlight, the louver design has a low pressure drop. The low pressure drop results in lower fan energy consumption, which reduces the operating costs of the cooler.

Pressurized Water Distribution System

EVAPCO's Zero Maintenance ZMII® Spray Nozzle remains clogfree while providing even and constant water distribution for reliable, scale-free evaporative cooling under all operating conditions. The heavy duty nylon ZM® Spray nozzles have a 33.3mm diameter opening and a 38mm splash plate clearance. Furthermore, the fixed position ZM® nozzles are mounted in corrosion-free PVC water distribution pipes that have threaded end caps. Together, these elements combine to provide unequaled coil coverage and scale prevention, and make the industry's best performing non-corrosive, maintenance-free water distribution system. 

Fast, On-Time Shipments

The cATW is completely factory assembled and manufactured by a dedicated professional workforce, expert in building closed circuit coolers. Factory trained mechanics and EVAPCO's strict quality control and inspection procedures guarantee the quality of every unit shipped.

EVAPCO's controlled factory environment ensures fast on-time shipments, allowing the cATW to be available WHEN THE CUSTOMER WANTS IT!

Easy Access

The cold water basin section is easily accessible from ground level by simply removing the (2) two Quick Release Fasteners on the inlet louver assemblies surrounding the closed circuit cooler and lifting out the lightweight louver. The basin can be accessed from all (4) four sides of the cooler. This open basin design enables the cATW basin to be easily cleaned.

Clean Pan Basin Design

The cATW features a sloped basin from the upper to lower pan section. This "Clean Pan" design allows the water to be completely drained from the basin. The closed circuit cooler water will drain from the upper section to the depressed lower pan section where the dirt and debris can be easily flushed out through the drain. This design helps prevent buildup of sedimentary deposits, biological films and minimizes standing water.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The cATW features a Quick Release Fastener design consisting of (2) two large thumbscrews and a latch system. By loosening the thumbscrews, the latch pulls up and out of the louver frame, allowing the louver to be removed while the latch and thumbscrews stay on the closed circuit cooler.

Motor Mount, Power Band Belt Adjustment and Bearing Lubrication

The fan motor and drive assembly are designed to allow easy servicing of the motor and adjustment of the belt tension from the exterior of the unit. The T.E.F.C fan motor is mounted on the outside on these models and is protected from the weather by a cover which swings away for maintenance.

A large hinged access door is located on the side of the unit for easy access to the fan drive system. The belt can be adjusted by tightening the J-Bolts on the motor base and the tension can be checked easily through the access door, all while standing at the side of the unit. The bearings can also be lubricated from the side of the unit. The bearing lubrication lines have been extended to the exterior casing and are located by the access door, thus making bearing lubrication easy. Sloped access ladders are available as an option to facilitate maintenance.

Fan Motors

All cATW Closed Circuit Cooler models utilize heavy duty totally enclosed (T.E.F.C.) fan motors designed specifically for closed circuit cooler applications. In addition to the standard fan motors offered on each cooler, EVAPCO offers many optional motors to meet your specific needs, including:

•  Premium Efficiency Motors
•  Multi-Speed Motors

for VFD Applications cATW models feature T.E.F.C. motors are located on the outside of the unit, protected by a hinged, swing away cover.

Power-Band Belt Drive

The Power-Band drive is a solid-back multigroove belt system that has high lateral rigidity. The belt is designed for closed circuit cooler service, and is constructed of neoprene with polyester cords. The drive belt is sized for 150 percent of the motor nameplate horsepower ensuring long and trouble free operation.

Drive System Sheaves

Drive system sheaves located in the warm, moist atmosphere inside the closed circuit cooler are constructed of an aluminum alloy. Those located externally are protected by a hinged cover.

Fan Shaft Bearings

The fan shaft bearings on the cATW Closed Circuit Cooler are specially selected to provide long life, minimizing costly downtime. They are rated for an L-10 life of 75,000 to 135,000 hours, making them the heaviest duty pillow block bearing in the industry used for Closed Circuit Cooler duty.

Five (5) Year Warranty

EVAPCO provides a standard five (5) year motor and drive warranty on all direct drive Power-Band belt drive and optional gear drive cATW Closed Circuit Coolers. This unique warranty is designed to offer the end user optimum protection against fan drive and motor failure. It is a comprehensive plan which includes the fan, fan shaft, sheaves, fan bearings, belts, gear box, flexible coupling, driveshaft and the motor.

Motor Davit

The Motor davit option eliminates crane rentals and facilitates the removal of motors and gear drives. The davit and bracket are constructed of heavy duty galvanized steel and are mounted on the side of the unit. The optional fan motor and gear davit ships loose and is installed in the field.

Sloped Access Ladders

The EVAPCO designed access ladder features a sloped "ships type" ladder arrangement which provides fast and easy access to the water distribution system and drive components. A grab bar is attached to the sloped ladder for safe and easy ascent and descent. There is no need for safety cages or railings with this design. The ladder(s) will ship loose and must be field mounted. The sloped ladder meets all applicable OSHA requirements.

 

Stainless Steel Water Touch Basin

The cATW Closed Circuit Cooler has a modular design which allows specific areas to be enhanced for increased corrosion protection. The basin area of the cooler experiences turbulent mixing of air and water, in addition to silt build-up. In conjunction with the EVAPCOAT Corrosion Protection System, EVAPCO offers an optional Stainless Steel Water Touch Basin. This option provides Type 304 or Type 316 stainless steel for the entire basin area including the support columns of the closed circuit cooler and the louver frames.

The basin section provides the structural support for the unit and is a critical part of the closed circuit cooler. The Stainless Steel Water Touch Basin provides maximum corrosion protection.

Extended Surface Coil

Closed circuit coolers can be provided with spiral fins on the heat exchanger coil to increase the dry performance of the unit. Dry performance is accomplished by rejecting heat to the atmosphere without the use of the spray pump and the evaporation process. Dry operation can be practical in cold climates and/or when reduced winter loads exist. The number of fins per inch and and quantity of rows finned can be varied to obtain different dry performances.

Electric Heaters

Electric immersion heaters are available as an option and are located in the basin of the cooler They are sized to maintain a +40° F (4,4º C) pan water temperature at 0°F (-18º C) ambient with the fans off *. They are furnished with a combination thermostat/low water protection device to cycle the heater on when required and to prevent the heater elements from energizing unless they are completely submerged. All components are enclosed in rugged, weather proof enclosures for outdoor use. Heater control packages that include contactor, transformer or disconnects are available.

(*) - Electric heater selection based on 0°F (-18º C) ambient temperature. For alternate low ambient heater selections consult the factory.

Electric Water Level Control

EVAPCO closed circuit coolers are available with an optional electric water level control system in place of the standard mechanical makeup valve and float assembly. This package provides very accurate control for the basin water level and does not require field adjustment, even under varying operating conditions.

The control was designed by EVAPCO and is manufactured exclusively for EVAPCO. It consists of multiple heavy duty stainless steel electrodes. These electrodes are mounted external to the unit in a vertical stand pipe. For winter operation, the stand pipe must be wrapped with electric heating cable and insulated to protect it from freezing.

The weather protected slow closing solenoid valve(s) for the makeup water connection is factory supplied and is ready for piping to a water supply with a pressure between 25 and 50 psig (138 kPa and 345 kPa).

Other Options

• Vibration Switches
• Remote Sump Connections
• Motors– Energy Efficient / Inverter Duty /2S/1W and 2S/2W / Mill and Chem Duty and Many More, Consult the Factory