Abstract: An apparatus for producing an oxygen enriched gas having a compressor for supplying air under pressure, a unit for producing a gas enriched with oxygen from the air supplied from the compressor, a gas storage tank for reserving the oxygen enriched gas produced from the producing unit, a flow rate setting unit to set a flow rate of the oxygen enriched gas delivered from the gas storage tank, and a regulating unit for adjustably regulating an oxygen concentration of the oxygen enriched gas in response to a change in a requirement of an oxygen concentration of the oxygen enriched gas obtained at an outlet of the apparatus.

Abstract: A method for producing a textured polyester yarn, especially in an in-draw texturing system, in which starting yarn is processed by means of a non-touch type heater under a heater temperature in a range of from 350.degree. C. to 800.degree. C. and a shorter processing time in a range of from 0.04 second to 0.12 second. The dyeing evenness of the fabric made from the resultant yarn is improved because the dyeability of the yarn is almost constant despite fluctuation of the heater temperature. A belt-type twister is preferably utilized for false-twisting a yarn rather than a disc type.