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FACTORY-ASSEMBLED (FAP) VS. FIELD-ERECTED (FEP) TOWERS

Induced draft cooling towers have fans that are typically mounted on top of the unit and pull air through the fill media. Conversely, air is pushed by blowers located at the base of the air inlet face on forced draft towers. Factory-assembled towers (FAP) are rebuilt and shipped in as few sections as the mode of transportation will permit. A relatively small tower will ship essentially intact. A larger, multi- cell cooling tower is manufactured as modules at the factory, and shipped ready for final assembly. Factory-assembled towers are also known as "packaged" or "FAP" (factory-assembled product). Factory-assembled cooling towers can be crossflow or counterflow, induced draft or forced draft, depending on the application. While all applications are different, the factory- assembled Marley NC crossflow, induced draft tower is widely used for HVAC and light industrial applications. Factory-assembled cooling towers can be crossflow or counterflow, induced draft or forced draft, depending on the application.

Field-erected cooling towers (FEP) Field-erected towers are primarily constructed at the site of ultimate use. All large cooling towers, and many of the smaller towers, are prefabricated, piece- marked, and shipped to the site for final assembly. The manufacturer usually provides labor and supervision for final assembly. Field-erected towers can be crossflow or counterflow, depending on the application. For power and heavy industrial applications, the field-erected Marley F400 counterflow tower can be customized to meet your exact specifications for performance, structure, drift and plume abatement.

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PERFORMANCE DRIVERS

Using a total system approach, every cooling tower and component is designed and engineered to work together as an integrated system for efficient performance and long life.



HVAC Free Cooling - A free cooling system allows the tower to directly satisfy a building's cooling needs without the need of operating the chiller in cold weather. The goal of a free cooling system is to save energy. There are specific types of free cooling systems and certain elements that must be in place for a free cooling system to be considered.


Variable Flow- There may be significant energy savings opportunities if the cooling tower can be operated under variable flow in off-peak conditions. Variable flow is a way to maximize the effectiveness of the installed tower capacity for whatever flow the process has.


OEM parts - Precision-engineered to provide a reliable product,  are built to the highest standards and tightest tolerances for extended service life.



Fill - One of the single most important components of a cooling tower is the fill. Its ability to promote both the maximum contact surface and the maximum contact time between air and water determines the efficiency of the cooling tower. The two basic fill classifications are splash type fill (breaks up the water) and film type fill (spreads the water into a thin layer).



Drift eliminators - Designed to remove water droplets from the discharged air and reduce loss of process water, drift eliminators cause the air and droplets to make sudden changes in direction. This causes the drops of water to be separated from the air and deposited back into the tower.



Nozzles - Crossflow configuration permits the use of a gravity-flow distribution system with a nozzle such as the Marley ST. With this system, the supply water is elevated to hot water distribution basins above the fill and then flows over the fill (by gravity) through nozzles located in the distribution basin floor. Counterflow configuration necessitates the use of a pressure type system of closed pipe and spray nozzles like the Marley NS.



Fans - Cooling tower fans must move large volumes of air efficiently, and with minimum vibration. The materials of manufacture must not only be compatible with their design, but must also be capable of withstanding the corrosive effects of the environment in which the fans are required to operate. The Marley Ultra Quiet fan is an example of a fan that can be used in situations where very low sound is a necessity.



Driveshafts - The driveshaft transmits power from the output shaft of the motor to the input shaft of the Geareducer. Because the driveshaft operates within the tower, it must be highly corrosion resistant. Turning at full motor speed, it must be well balanced and capable of being re-balanced. Due to the rigorous cooling tower specification requirements, the Marley Comp-DS carbon-fiber driveshaft was designed.