| 摘要 |
PURPOSE:To lower the manufacturing cost of a base material for an optical fiber through reducing the amount of used He by recovering exhaust gas from an electric furnace, separating gaseous He alone, adding necessary components, and feedig them to the furnace again. CONSTITUTION:In the manufacture of a base material for an optical fiber by a VAD method, a mixed gas of He, O2, SOCl2, etc. is fed into electric furnace 23 from feeder 25. OH groups and H2O molecules in a porous base material chemically react with the SOCl2, forming SO2 and H2O. As a result, gaseous He contg. SO2, H2O, O2, etc. is exhausted from exhaust port 27. This exhaust gas is passed through gas separator 26 to separate gaseous He alone, and the He is carried to feeder 25, where lost SOCl2, O2 and He are added to adjust the composition to the same compsn. as is the initial conditions. The resulting mixed gas is fed into furnace 23 again. By this method loss of expensive gaseous He can be reduced remarkably. |
