A method of forming an optical fiber preform includes the steps: igniting a burner having a fume tube assembly to produce a first spray size of silicon dioxide particles; depositing the silicon dioxide particles on a core cane to produce a soot blank; and adjusting an effective diameter of an aperture of the fume tube assembly to produce a second spray size of the silicon dioxide particles. The second spray size is larger than the first spray size.

A method for manufacturing a glass particle deposit according to one aspect of the present disclosure includes manufacturing the glass particle deposit by producing glass particles through a hydrolysis reaction using flame of a burner and depositing the glass particles on a target in a reaction container, and taking out the glass particle deposit from the reaction container and transporting the glass particle deposit to a clean room. Air is introduced into the clean room through a clean room filter that removes particles in the air. When the glass particle deposit is manufactured, air is introduced from a space different from the clean room into the reaction container through a reaction container filter.

An optical fiber base material manufacturing apparatus including a reaction chamber; a burner that has a portion thereof inserted into the reaction chamber through an insertion opening that creates a connection between the inside and outside of the reaction chamber, and emits a flame toward a starting member positioned within the reaction chamber; and a seal connection member that creates an air-tight seal between the burner and the reaction chamber at the insertion opening. One end of the seal connection member firmly contacts the burner inserted therethrough, another end of the seal connection member firmly contacts the reaction chamber and has a through-hole formed therein through which the burner is inserted without contacting the seal connection member, and the seal connection member includes a connecting portion that connects the one end to the other end, while preventing transfer of stress between the one end and the other end.

A production method for a glass particulate deposit which includes a deposition step in which, at least two liquid source material ejecting ports 31a for a glass source material 23 jetting out from a burner 22 are provided per one burner 22, the area of at least one liquid source material port 31a is 2.2510.sup.4 or less of the area of the flame forming part of the burner 22, the glass source material 23 is, in the form of a liquid thereof, supplied to each liquid material source port 31a, jetting gas ports 31b are arranged in such a manner that the inner periphery of the jetting gas port is positioned outside by 1.0 mm or less from the outer periphery of each liquid source material port 31a, and a gas is jetted out from each gas jetting port 31b.

A soot glass deposit body is manufactured by placing a starting rod and a burner 22 for producing glass particulates in a reaction container, introducing a source material gas to the burner 22 through a supplying pipe 26, producing glass particulates by a pyrolytic oxidation reaction of the source material gas in a flame formed by the burner 22, and depositing the produced glass particulates on the starting rod. At the time, the source material gas to be supplied to the burner 22 is a siloxane, the burner 22 is heated so that temperature of the burner 22 falls within the range of from 30 C. to +30 C. relative to the boiling point of the siloxane, and also temperature of the supplying pipe is controlled within the range of from the boiling point of the siloxane to the boiling point plus 30 C.

Provided is a glass particulate deposit manufacturing method for manufacturing a glass particulate deposit comprising mounting a fixing jig on an outer periphery of an outermost pipe of a burner; inserting a burner cover from a tip end of the outermost pipe of the burner; and sandwiching and compressing a part of the fixing jig between the burner cover and the outermost pipe of the burner to fix the burner cover to the burner, wherein an outer diameter of a part of the fixing jig that is not compressed is greater than an inner diameter of a part of the burner cover inserted to the tip end of the outermost pipe of the burner.