Sensor Electronics” optical gas analyzers measure EtO (ethylene oxide) concentrations in medical sterilization chambers. The company”s new dual-gas analyzer meets FDA requirements for precise data collection. In a sterilization chamber it gives accurate (within +/- 3 percent) readouts of both EtO and H2O (steam is used to enhance efficacy of EtO) despite abrupt changes in chamber temperature, humidity, pressure, condensation levels, product gas absorption. In petrochemical applications, the analyzer can give continuous readout of natural gas and CO2 levels despite varying pressures, proportions, and flows. The standalone dual-gas analyzer uses nonextractive sampling and patent-pending optical technology to simultaneously measure volumetric concentrations of two gases, as, for example, a hydrocarbon plus H2O or CO2.