Infrared CO₂ sensors offer fast recovery times and a seven-year warranty. Incubators with IR sensors are used in applications with frequent door opening because CO₂ recovery is unaffected by changes in temperature or humidity. Continuously sampling the chamber atmosphere through a spectrophotometer flow cell, the IR sensor checks wavelength and rectifies an out-of-control condition. Recovery is rapid and changes in CO₂ concentrations are made within seconds.