High purity sulfur hexafluoride is an important medium in the electric power industry.It is used as an arc extinguishing and insulating gas in enclosed and high voltage switches.The ultimate performance of SF6 gas enables the device to operate economically and with low maintenance.At present,there is no other technology that can surpass SF6 gas from a technical,economic and ecological point of view as an insulating and arc extinguishing medium.

　　Because the gas has been widely used in electrical equipment.From the application point of view,high purity sulfur hexafluoride circuit breaker and GIS is the main field of***,has basically replaced 126kV and above voltage grade oil circuit breaker.Obviously,SF6 gas instead of insulating oil as arc extinguishing and insulating medium is the inevitable trend of development.

　　With the deep and wide application of high purity sulfur hexafluoride electrical equipment in China,the consumption of this gas is increasing.Due to the high purity gas is expensive,and when SF6 gas contains water,it will cause the following harm to electrical equipment:

　　(1)In the presence of water,high purity sulfur hexafluoride decomposition products hydrolysis reaction,hinder the composite of SF6 decomposition products,reduce the medium recovery strength of SF6,thereby reducing the insulation characteristics of equipment;

　　(2)the hydrolysis of low fluoride and the decomposition of metal fluoride are intensified.The generated fluorinated sulfite and hydrofluoric acid are highly toxic,harmful to human body,and will corrode electrodes and insulation materials;

　　(3)Condensation in the equipment.The moisture in the high-purity sulfur hexafluoride gas exists in the form of water vapor.When the temperature drops,it may form dew inside the equipment and adhere to the surface of the equipment,such as electrodes and insulators,which is easy to produce surface discharge(flashover)and cause accidents.

　　(4)Fluorinated sulfite and hydrofluoric acid will pollute the environment if they are put into the atmosphere.Therefore,high-purity sulfur hexafluoride electrical equipment should be recovered and purified in the production and maintenance of SF6 gas,and remove the moisture and decomposition products in SF6 gas in time.

　　It is because of the above hazards that sulfur hexafluoride recovery and purification device arises at the historic moment and becomes a necessary equipment for SF6 electrical equipment users and SF6 electrical equipment manufacturers to produce,repair and support.