Patent ID: 6255653
Filing Date: 2001-07-03
Classification: G01N

Abstract:
An improved diffusion-type Non-Dispersive Infrared gas analyzer, comprising:a specularly reflective waveguide with a plurality of apertures which includes a first aperture located in a first portion of the waveguide and a second aperture located in a second portion of the waveguide;an infrared source located proximate to a first end of the waveguide in the first portion of the waveguide;a window located in a second end of the waveguide in the second portion of the waveguide;a detector located proximate to the second end of the waveguide which is thermally isolated by the window from the waveguide;a semi-permeable membrane made of a hydrophobic material with a thickness sufficient to provide its own structural integrity which surrounds the waveguide and creates a diffusion pocket of space between the membrane and the waveguide;wherein the plurality of apertures are sized and spaced apart such that gas flow into the waveguide is assisted by a convection flow created by a temperature gradient between gas located within the waveguide and gas located within the pocket.