Methods and apparatus for controlling gas flows

Abstract

A chamber is isolated from ambient atmosphere by supplying a flow of inert gas to the entrance and/or exit of the chamber such as an oven for curing solvent borne resin coatings on a material passed therethrough. The inert gas is supplied at a substantially constant mass flow rate through an orifice which may be adjusted in opening or direction so as to enable the momentum of discharged inert gas to be controlled. A flow of gas is exhausted exteriorly of but in the vicinity of the chamber exit or entrance and the oxygen content of such flow is sensed. The sensed oxygen value is compared with a predetermined value and the difference is utilized to adjust the orifice to either increase or decrease the momentum of inert gas discharged therefrom. In this manner atmospheric oxygen is precluded from entering the chamber while only the amount (flow) of inert gas necessary to block such oxygen is utilized thereby minimizing the loss of inert gas from the chamber to ambient.

Dependencies are inferred from the claim text.