APPARATUS FOR PRODUCTION OF POROUS PREFORM FOR OPTICAL FIBER AND PRODUCTION THEREFOR

摘要

PROBLEM TO BE SOLVED: To produce a large-sized porous preform for an optical fiber stably for a period longer than heretofore and simultaneously, to improve the productivity of the porous preform for the optical fiber by making the life of an exhaust system consisting of a heat resistant flexible hose and a stationary exhaust pipe longer than heretofore. SOLUTION: A gas intake 21 is disposed between an air exit 6 and the heat resistant flexible hose 1. This gas intake 21 is provided with a damper 22 and its opening degree is regulated to take in the gas. The gas is mixed with the exhaust gases flowing from the air exit 6 into the flexible hose 19, by which the temperature in the flexible hose 19 is kept below its heat resistant temperature and the life of the exhaust system is prolonged.