ADK series applies for dry air supply on maintenance work of transformers, reactors and other large electrical equipment. Provide dry air to ensure that the internal insulation of electrical equipment will not be damp, and maintenance personnel working within the device will not suffocate from lack of oxygen. The system is much safer, more reliable, more economical and more convenient than nitrogen system. By using ADK, the maintaining work is not influenced by climate change. Especially for the overnight operation, just seal around the flange, fill dry air 0.02~0.03MPa, while the transformers and reactors won't damp without oiling. Reducing the daily pumping and oiling work, to shorten the repair period and improve the quality of maintenance. Inflating the dry air to the fuel injection device and oil inflate in the purify process, can improve insulation and reduce water when it is in rainy and humid environment. ADK can also used as indoor air condition when it is left unused.