Gas industry terminology
The vibration and rotation spectra of most gas molecules are in the infrared band. When the frequency of the incident infrared radiation is the same as the characteristic frequency of the vibrational rotation of the molecules, the infrared radiation will be absorbed by the gas molecules, causing the attenuation of the radiation intensity. An infrared gas analyzer made using the principle of absorption of infrared radiation by this gas molecule has the characteristics of high measurement accuracy, fast speed, and continuous measurement, in the industrial departments of iron and steel, petrochemicals, fertilizers, machinery, etc. Instrument is an important monitoring method for production process control; it also has many successful applications in environmental pollution component detection and medical physiology research.
The operation of these infrared gas analyzers is based on the infrared absorption characteristics of the gas. Using a single infrared beam to detect the gas concentration, the analyzer produces results with high stability and reliability. The single infrared light beam is adjusted by the chopper and passes through a sample cell containing a predetermined length of gas sample to be analyzed. When the beam passes, the gas sample absorbs part of its energy. The energy-reduced beam exits the sample cell and is directed into the front chamber of a two-chamber infrared detector. The detector is filled with the gas to be detected, and then the energy of the beam is absorbed again. This receiving process increases the pressure in both chambers. The pressure difference between the front and back chambers of the detector creates a fine gas flow between the two chambers. A gas flow sensor detects the gas flow and converts it into an AC signal. Then the AC signal is expanded and adjusted to a DC voltage signal, which is finally provided to the output terminals and indicators. This electrical output signal is proportional to the concentration of the sample gas.