Portable air conditioning is a popular choice for temporary cooling when installed HVAC equipment is offline for refurbishment or repair. When the space being served is a manufacturing cleanroom, the temporary cooling requirements become more complex. A 12-ton mobile cooling unit supplied by Atlas Sales & Rentals, Inc. provided an effective solution for Swift Engineering a San Clemente, Calif. company specializing in the design, development and manufacturing of lightweight composite structures, components and vehicles. Portable cooling allowed Swift to maintain required temperatures and air quality in their aerospace composites manufacturing cleanroom during the two-week shutdown of their permanent a/c equipment.
The unit supplied for the job was a compact, yet powerful, 12-ton portable air conditioner. It was positioned in a warehouse area adjacent to the 56,000 cu ft. cleanroom to which cool air was delivered while the permanent 9-ton and 5-ton air handling units serving that area were refurbished.
According to Swift purchasing manager Steve Pascoe, “To meet Class 100,000 cleanroom standards, we needed to keep the temperature below 75 degrees F during layup operations. Another requirement was to maintain air cleanliness, and to accomplish that Atlas helped us devise a system that would not draw any outside air into the space.”
Four 12”-diameter ducts to the evaporator – two on the supply side and two on the return side – were hooked up. The return ducts pulled the air from inside the space, where it passed through the air conditioner across the evaporator coil, removing excess heat and moisture before recirculating the cooled air back into the space. A temporary plywood bulkhead with 12” openings for the ducts was built to isolate the cleanroom and provide good air flow for the temporary a/c system. Swift built the bulkhead in-house to ensure that it would meet their specifications. Condensate was removed through a side drain line equipped with a P-trap to prevent backflow. Condensate water collected in a drain pan beneath the evaporator coil and flowed out through a drain in the warehouse. A large exhaust duct on the condenser section of the portable cooler vented hot air outside to maintain comfortable warehouse temperatures.
Pascoe commented: “The 12-ton portable worked very well and had no problem keeping up with demand. Operating noise was not an issue either for employees working in the warehouse; in fact, it was quieter than our permanent air handling units.
Atlas regional manager John Wheeler noted that the unit, “…provides 12 tons (144,000 BTU/hr) of cooling – yet at 34” wide, it’s narrow enough to roll through a standard doorway. It can go where most other 12-ton units can’t – for example, server rooms, conference and meeting rooms, offices and many other locations.”
High-efficiency radial blowers with built-in variable speed motors provide uniform airflow across the evaporator coil of the portable cooler. These premium blowers are designed to operate at higher pressure with less turbulence and noise than standard fans. Combined with the use of acoustical insulation in the evaporator section, the blowers ensure an unusually low sound level for a unit of this size. Installation and maintenance ease are additional features of the 12-ton cooler.
Clark Michel is with Atlas Sales & Rentals, a national distributor of portable cooling and heating products. www.atlassales.com
