Apparatus for producing oxidized filaments

An apparatus for continuously producing continuous oxidized filaments which comprises an oxidizing furnace having a heated oxidizing gas atmosphere therein, into which continuous precursor filaments such as polyacrylaonitle filaments are continuously introduced, in which the precursor filaments are converted into oxidized filaments and from which the oxidized filaments are continuously drawn out, a first duct communicated with the furnace to provide a flow of an oxidizing gas such as heated air having a temperature in the range of from about 200 DEG C. to about 300 DEG C. into the furnace, a second duct communicated with the furnace to exhaust gas from the furnace, a conduit connected to the furnace to draw off a part of gas in the furnace together with sealing air introducing from the outside of the furnace into the furnace, an injecting means provided in the way of the conduit for injecting water in the form of liquid and/or in the form of steam to extinguish the fire in the conduit, a shutting means provided in the way of the conduit to shut a flow of gas in the conduit, and a water spraying means provided in the furnace to extinguish the fire in the furnace.