| CPC C03B 37/0146 (2013.01) | 14 Claims |
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1. An apparatus for drying and/or consolidating an at least partially porous optical fibre preform, comprising:
a furnace comprising a muffle tube extending along a vertical axis (Z) and forming a hollow muffle chamber configured to house a preform, the muffle tube having a muffle opening at its top side, which is configured to allow passage of the preform;
an extension tube forming a hollow extension chamber configured to house at least a length portion of the preform and having a central axis aligned in the vertical axis (Z), wherein the extension tube has a lower opening and upper opening placed at the top side of the extension tube and opposite to the lower opening, and wherein the extension tube is removably attached to the muffle tube at the lower opening so as to close the muffle opening when the extension tube is joined to the muffle tube to form a single chamber,
a hood placed on a top side of the extension tube and removably fixed to the same, the hood defining an inner space when fixed to the extension tube and including a discharge port and a hood cap with a hood through-hole which is substantially axially aligned to the upper opening, the hood through-hole and the upper opening being configured for the passage of a cylindrical supporting rod of a supporting handle for the suspension of the preform, and
a flow control assembly including a sealing assembly operatively connected with the hood and substantially centred about the vertical axis (Z), wherein the sealing assembly includes a ring-shaped seal and an expansible member having a generally tubular shape configured to allow passage of the supporting rod and to expand and contract in a vertical direction (L), wherein the ring-shaped seal is located radially inward of the expansible member and operatively connected thereto and has an inner diameter configured to directly contact the supporting rod.
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