Infrared monitor and control for vapor hydrogen peroxide processing techniques

A vaporizer ( 14 ) supplies hydrogen peroxide and water vapor to a high level disinfection or sterilization region ( 20 ). Mid-infrared light detectors ( 32 ) detect light in the mid-infrared range which has traversed a region of the treatment chamber in a first narrow spectrum centered at 8,000 nanometers which is absorbed by the hydrogen peroxide vapor, a second narrow spectrum which is absorbed by the water vapor, and a third spectrum that is absorbed by neither the hydrogen peroxide vapor nor the water vapor. From these measurements, an absorbance or transmittance is determined ( 40 ) from which the concentrations of hydrogen peroxide and water vapor are determined ( 42 ). Monitored temperature ( 44 ) and the determined concentrations are converted into a percent saturation ( 54 ). The supply of hydrogen peroxide and water vapor to the chamber is controlled ( 60 ) in accordance with the determined percent saturation.