Optical gas densitometer

An optical gas densitometer including an optical source for transmitting an optical beam, and a detection section for receiving said optical beam and for measuring the density of a particular gas, comprising:

• a holding cell portion having front and rear ends;
• filter portion means disposed inside said holding cell portion and having front and rear ends corresponding to said front and rear ends of said holding cell;
• a gas sampling tube for insertion into a flow channel of the gas to be measured, said tube having one end open to receive gas and a second end attached to the front end of said holding cell;
• fork plate means at said front end of said filter portion means for dividing the space between said holding cell and said filter portion means into a gas feed channel below said plate means and a gas exhaust channel above said plate means, said plate means extending substantially from said front end of said filter means to a point short of said rear end of said filter means, such that the area short of said rear end not divided by said plate means forms an open passage between the feed and exhaust channels;
• partition plate means disposed inside said gas sampling tube for dividing said tube into a first channel below said partition plate means and a second channel above said partition plate, said partition plate means being aligned with said fork plate means so that said first channel corresponds to said feed channel and said second channel corresponds to said exhaust channel;
• window openings situated at the rear end of said filter portion means for allowing said optical beam to enter and to exit said holding cell and the filter portion means;
• and
• reflecting means disposed at said front end of said filter portion means for reflecting said optical beam towards said detection system at a predetermined angle;
• such that upon inserting said gas sampling tube into a flow channel of the gas, said gas to be measured flows through said first channel, into said feed channel, into said open channel, into said exhaust channel and out said second channel, whereupon the gas which diffuses through said filter portion means into said holding cell affects said optical beam and allows said detection system to measure the density of said gas.