Abstract: A glass tube (31) from which optical fiber is to be drawn is heated by a torch assembly comprising a plurality of nozzles (54--54) disposed on a carriage. In order to avoid contamination of the tube by particles of the torch assembly resulting from thermal degradation,the nozzles are disposed in a plane which is normal to an axis (36) of the tube with each nozzle axis inclined so that flame fronts associated with the nozzles are substantially closer to the tube than to the torch assembly. Reaction of materials which are flowed into the tube is enhanced by including a second row of nozzles (91--91) which are inclined within a plane which is inclined to the longitudinal axis of the tube. In order to collapse the tube into a rod, a muffle member (100) preferably is caused to be disposed about the tube with an opening in the periphery of the muffle member to allow portions of the gas flows to converge and to allow heat energy to be transferred from the flame fronts to the tube.

Abstract: Apparatus for supplying fluid to a rotary tube uncontaminated with ambient air comprises an end cap having an open ended bore in which an end portion of the tube may be rotatably positioned, a first conduit extending into the end cap through which fluid may be fed into the rotary tube, and a second conduit communicating with the end cap bore through which a purge fluid may be fed into and at least partially through the bore to the exterior of the end cap.

Abstract: A method of introducing a vapor stream into a rotating optical fiber preform tube comprising the steps of: (a) generating a vapor stream comprised of a vaporized glass forming precursor entrained in an oxidizing carrier gas; (b) flowing the vapor stream into the rotating optical fiber preform tube through a sealed rotary joint; and (c) preventing any material alteration in the composition of the vapor stream from occurring should the sealed rotary joint become leaky by flowing a stream of fluid consisting essentially of the oxidizing carrier gas over the rotary joint at a pressure greater than the pressure of the vapor stream as it flows through the rotary joint.