A controlled atmosphere (CA) storage facility is a modern type of storage for goods, widely used in developed countries for preserving fruits like apples and pears through controlled atmosphere technology. The construction of a CA storage unit not only requires insulation and moisture protection but also the ability to block gases, demanding high airtightness to maintain the required concentrations of oxygen and carbon dioxide within the storage. It must also be capable of withstanding certain pressures during fluctuations in internal air pressure. The airtight layer is typically made with galvanized steel plates, thin iron plate welds, or high-density plywood and foil-faced insulation boards for sealing. Currently, aluminum (or steel) prefabricated sandwich panels with polystyrene foam or polyurethane foam as the core are widely used. These panels can serve triple functions of vapor barrier, thermal insulation, and gas barrier, capable of blocking a temperature difference of up to 40°C. Their airtightness is considered adequate if, when subjected to a positive or negative pressure of at least 15 mm water column difference between the inside and outside of the storage unit, the pressure does not return to its original level within 30 minutes, indicating they meet the standards.

The gas composition in a controlled atmosphere storage room must be regulated by the controlled atmosphere equipment, primarily involving oxygen reduction and carbon dioxide removal devices. The oxygen reduction equipment includes four types ranging from primary to advanced: combustion nitrogen generators, carbon molecular sieve nitrogen generators, hollow fiber membrane nitrogen generators, and cracking ammonia nitrogen generators. The carbon dioxide removal devices mainly utilize activated carbon adsorption and elution for half-pressure drop, and can also use sodium hydroxide aqueous solution for elution, as well as silicone rubber membrane filtration for elution, which involves the absorption of calcium hydroxide.

The controlled atmosphere storage can adjust the appropriate temperature, humidity, low oxygen, and high carbon dioxide gas environment according to the requirements of different fruits and vegetables. It can also eliminate harmful gases like ethylene released during their respiratory metabolism, thereby achieving better suppression of product respiration intensity and delaying the senescence and aging process than simple refrigeration. Although controlled atmosphere storage has the aforementioned advantages, not all fruits and vegetables can be stored in it, and the storage effects will not always surpass refrigeration. It is a large-scale centralized facility for storage and sale, which is less flexible in terms of inventory turnover compared to conventional cold storage due to the inconvenience of adjusting gas composition within the storage once. After a concentrated, short-term storage and loading of the storage room, the door must be sealed properly, and then the internal temperature and gas are regulated by refrigeration and controlled atmosphere equipment. During the storage period, personnel are not allowed to enter the storage at will (respirators are required upon entry), and generally, they can only check the internal conditions through observation ports and according to market needs. The door should not be opened arbitrarily until the storage is complete, allowing the gas to return to normal, and then the facility can be accessed for shipment.