The purity of a gas is an indication of the amount of other gases contained in it. A high purity refers to a low amount of other gases. High purity gas are considered to be of better quality and are generally more expensive.
The purity of the gas can be expressed as a percentage or as a decimal fraction.
Applications for checking the purity of the gases across different industrial sectors by air separation plants, cryogenic facilities, the quality control of industrial gases to the steel mills, etc. ..
ETG has various instruments according to specific needs. In particular is monitored the level of nitrogen in different gas mixtures. A second economic needs is available the measurement of traces of nitrogen or only in Argon and / or helium or in a gas mixture of different
The field of application of analytical procedures is extremely broad. For example for verify the quality of the food, to test the engines in the automotive industry, for process control in the chemical or pharmaceutical industry, in medicine, in metallurgy or in environmental monitoring, analytical methods are performed for process control, quality assurance or to demonstrate compliance with the requirements of the law
METHODS OF ANALYSIS
Analytical methods used are as numerous as are the fields of application. In analytical chemistry, the analysis with gas as a special area of organic and inorganic analysis, has undergone significant development over the last thirty years, if at the beginning of the seventies the classical methods volumetric absorption and trimetrici you were still industrial practice current and gas chromatographs still a rarity, is now prefer the instrumental analysis.
Gas chromatography is used to analyze mixtures of gaseous or volatile liquid compounds. Via a special injector, the prepared sample is placed in a column separator. The individual substances interact with the material of the column separator in different ways depending on the type of substance. The gas-carrier transports the individual substances through the separator column at different speeds depending on the intensity of the interaction. Because of the relatively short time of analysis, is usually employed as a carrier gas helium, but often are also used nitrogen or hydrogen.
Exploits the principle of electroluminescence with a cell emission elettroscopica (without the aid of lamps) via an electromagnetic field. The gas is ionized and detected by the use of a detector for emissions Plasma; when the nitrogen concentration changes within Argon or Helium, will also change its spectrum
Mass spectrometry for the analysis of gas is in common use today, even in standard operations monitoring, for example at train refueling, air separation plants, or even in the filling of pure gases. The ionization method most widely used is the electronic impact ionization; examples are special cases of the atmospheric pressure ionization (Atmospheric Pressure Ionisation – APIMS) for the measurement of traces in pure gases, and ionization by inductively coupled plasma which, as in emission spectrometry, is used for the sensitive analysis of metals in reactive gases
The chemiluminescent analyzers are used for the determination of nitrogen oxides NO / NOx, and emission spectroscopy in the UV excitation with visible Plasma for analysis of purity of reactive gases.
FTIR and NDIR
The UV spectroscopy of the field until the IR field is used in some cases for the analysis of gas mixtures. Particularly popular are the NDIR monitor for the analysis of carbon monoxide or carbon dioxide in the exhaust gas of automobiles.
The analysis ensures the quality
The analytical procedures are now an essential part of daily practice in various fields of activity. The reliability and accuracy of the results obtained depend on many secondary conditions, very often the quality of the process gas and calibration employees plays a decisive role.