Investigation of the Feasibility of an NDIR Technique to Detect CO2in a Hyperbaric Gaseous Environment.

摘要

A nondispersive infrared (NDIR) technique for monitoring CO2has been thoroughly evaluated to determine its suitability for use in a hyperbaric environment. The technique used is to subject a known volume of sample gas to a periodic density modulation and to measure the amount of CO2present by observing the fractional change in a beam of infrared radiation transmitted through that volume. Experimental results indicate the validity of the technique for total pressures up to 1200psia,in He containing up to 15psia of O2/N2,and CO2partial pressures up to 30mm. A single point calibration with CO2span gas at any pressure should be necessary only infrequently. Response times of the order of a few seconds are possible. It is anticipated that this technique can be used in a CO2alarm sensor for inclusion in a saturation diver's breathing apparatus,as well as in hyperbaric habitats and Personnel Transfer Capsules. (Modified author abstract)