| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a porous glass preform for optical fiber having an excellent long-term durability. SOLUTION: The apparatus is equipped with a glass synthesizing burner 10, a gas supplying source which supplies a glass raw material gas to the burner 10, and a gas supplying pipe 20 connecting the gas supplying source and the glass synthesizing burner 10. The gas supplying pipe 20 contains at least one layer comprising a flexible synthetic resin and satisfies the expression: 0≤P/L<1.0×10<SP>-10</SP>, wherein P (g×cm/cm<SP>2</SP>×s×cmHg) is the coefficient of moisture permeability and L (cm) is the thickness. COPYRIGHT: (C)2005,JPO&NCIPI
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