| 摘要 |
PROBLEM TO BE SOLVED: To improve workability under a condition that since a sealing connection part of a column is arranged on an upper depth of an oven, the sealing connection part is shadowed by a hand and cannot be easily viewed in sealing connection work of the column.SOLUTION: A both-end opened tube 5 composed of quartz glass or the like having visible light transmissivity and heat resistance is inserted into an oven 1 and light is transmitted from a light source 8 arranged on the outside of the oven 1 through an inner space of the tube in order to suppress heat transmission from the inside of the oven 1 to illuminate sealing connection parts 10 and 11.SELECTED DRAWING: Figure 1 |
