The Chemgard Gas Monitor uses photoacoustic infrared technology, allowing operation for months with virtually no zero drift. This technology takes a gas sample into the monitor’s measurement chamber and exposes the sample to a specific wavelength of infrared light. If the sample contains the gas of interest, that sample will absorb an amount of infrared light proportional to the gas concentration that is present in the sample. Photoacoustic infrared analysis, however, extends beyond simply measuring the amount of infrared light that is absorbed; this technology actually detects what occurs after the gas is absorbed. Always in motion, gas molecules move around the inside of the measurement chamber, generating pressure. A highly sensitive microphone detects the audible pulse to the lowest of gas levels. With PAIR technology, there is no downtime, and no fresh-air sampling lines are needed.