The methods used to cool people, equipment, and processes in plant and manufacturing areas changed in 1984 when portable air conditioners for industrial high-ambient applications were introduced to the United States. Portable-air-conditioner designs had been tested outside of the United States for more than 10 years, prompting the development of ANSI/ASHRAE Standard 128, Method of Rating Unitary Spot Air Conditioners, which has become the standard for all spot- and direct-cooling applications.

Standard 128-compliant portable air conditioners allow people, equipment, and processes in high-ambient areas to be cooled without the generation of excessive cooling temperatures, airflow rates, or air volumes that could lead to heath issues. Various models can cool a single person, several people, or an entire assembly line. Larger units with 3 to 5 tons of cooling capacity can be rolled into place or hung from a ceiling and ducted over workers in an assembly or work area.

Providing a cooler and dryer workplace can lead to improved health and safety and increased productivity. For example, a cooling station can help workers cleaning out vessels or industrial storage tanks to avoid having to take "exhaustion breaks."

The design characteristics of portable air conditioners can improve the use and effectiveness of cooling in high-ambient areas inside or outside of a plant or in open areas in which traditional air conditioners are inadequate. Available in 115-v, 208-to-230-v, and 460-v models for normal industrial applications, portable air conditioners typically include wheels for portability, heavy-duty metal cabinetry, an internal refrigeration system, and moveable airflow nozzles for directing or ducting airflow.

Portable air conditioners protect employees, processes, and equipment from hot environments and can operate in temperatures as high as 115 F. Utilizing spot cooling for industrial processes can help protect products, such as small electronic chips, plastic-molded items, metal extrusions, rubber items, metal bars, and glass products, by increasing flow rates, curing products to specifications, removing unwanted moisture, and preserving product shapes and integrity. Products coming down a process line can be freed from deformity and produced 50 to 90 percent more quickly.

Relieving production equipment of excessive heat can lead to increased asset life and reliability. For example, electrical control panels affected by summer heat could receive additional help from portable air conditioners. Electric-furnace operations, nuclear-plant control areas, and process control rooms that lose cooling or need additional cooling for equipment and people can be candidates for spot cooling. Portable air conditioners also have improved the life and reliability of numeric-control (NC) machines.

Cooling industrial areas with portable units is not an exact science. Renting a portable air conditioner first can be an inexpensive method of proving a portable unit's ability to cool an application.

Standard 128-compliant Designs

Tested for cooling capacity at 95 F ambient temperature and 60-percent relative humidity at their condenser and evaporator coils, Standard 128-compliant portable air conditioners require a specific volume (270 cfm) and air velocity (33 fps) to produce a delta-T of 19.8 F. The delta-T is the actual temperature difference between the airflow into a portable unit's evaporator section and the air coming out of the unit's grilles or nozzles (Figure 1).

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