Manufacturing apparatus and manufacturing method of porous glass base material for optical fiber

A manufacturing method of a porous glass base material for optical fiber comprising:

• controlling a flow rate of a raw material liquid of an organic siloxane by a liquid mass flow controller;
• introducing the raw material liquid supplied from the liquid mass flow controller to a raw material liquid nozzle of a vaporizer by a raw material liquid pipe;
• ejecting the raw material liquid from the raw material liquid nozzle into the vaporizer;
• mixing the raw material liquid ejected in the vaporizer and a carrier gas to vaporize the raw material liquid to form a mixed gas in which the raw material gas and the carrier gas are mixed;
• supplying the mixed gas to a burner;
• combusting the mixed gas together with a combustible gas and a combustion supporting gas in the burner to produce SiO2 particles;
• depositing SiO2 particles on a starting core base material to form the porous glass base material for optical fiber;
• closing an open/close valve provided on a flow path of the raw material liquid pipe to stop the supply of the raw material liquid from the liquid mass flow controller, while continuing to supply the carrier gas, combustible gas, and combustion supporting gas;
• and
• supplying a purge gas from a purge gas supply pipe that joins the raw material liquid pipe between the open/close valve and the raw material liquid nozzle to the raw material liquid pipe after the closing of the open/close valve.