| 摘要 |
The purpose of the invention is to ensure the safety of an operator and minimize the area in which purging is halted. The internal space of a device is divided into a work area and a non-work area, and purging products in the work area is halted while purging of products in the non-work area is carried on. The oxygen concentration in the work area is measured, and if the oxygen concentration in the work area decreases to a predetermined value or lower, purging of products in the non-work area is halted. |
