publication_number US 5122255 A abstract an atmosphere control system including a standard gas supplying device for supplying a gas of a determined composition an oxygen concentration controlling device connected to the standard gas supplying device for adjusting oxygen concentration of the gas of the determined composition an atmosphere holding device connected to the oxygen concentration controlling device for receiving the oxygen concentration adjusted gas and an oxygen concentration measuring device arranged at the upstream side of the atmosphere holding device between the standard gas supplying device and the oxygen concentration controlling device or between the oxygen concentration controlling device and the atmosphere holding device or at the downstream side of the atmosphere holding device for measuring oxygen concentration in the gas at the position of the oxygen concentration measuring device is provided the present system can provide gases of low oxygen concentration easily and precisely control oxygen concentration in the gas of the system and prevent oxidization of articles in treating thereof in the atmosphere holding device application_number US 44080689 A description hereinafter the present invention will be explained in more detail with reference to examples referring to fig1 a structure of an embodiment of the oxygen concentration controlling device constituting the atmosphere control system of the present invention is shown in a flow diagram in this embodiment a pair of an outer electrode 2.