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Standard Gases Gas Replacement
Oct 27, 2017

Standard Gases Gas replacement

For the just after the repair or just completed the preparation of standard gas pipeline, there will be a certain amount of air in the pipeline, the need for gas replacement, if this time with the direct replacement of natural gas there will be a very great security risks, Because the actual amount of natural gas in the air is between 5% and 15%, the mixture will explode very easily. Therefore, when replacing air, it must not be natural gas, but it needs to be replaced with nitrogen. In the natural gas standard gas is the main component of methane, under normal circumstances the methane content can account for more than 90% of the weather, which also contains butane, propane, and ethane and some hydrocarbon gases and carbon dioxide, nitrogen and so on Some non-hydrocarbon gases. Natural gas after burning will not produce waste water, waste residue, and oil, coal and other energy can be compared with the clean, high calorific value and the use of security and other advantages. Nitrogen is an odorless, odorless, odorless gas that is not toxic in general. The volume fraction of nitrogen in the air is 78.12%, which is a very important component in the atmosphere. At room temperature in the case of gas state, under standard pressure, it will be cooled to minus 195.8 degrees Celsius will become no color to cool to minus 209.86 degrees Celsius, the nitrogen will become solid, was flower-like. Nitrogen has a very stable chemical temperament, under normal circumstances will not react with other substances. Unlike other gases, the requirements for cylinders containing electronic standard gases are very strict. Otherwise, even if the accuracy of the mixed gas is high, the stability can not be used anymore. First mixed gas cylinders geometric dimensions such as volume, diameter, bottle height to meet user requirements. In the field of semiconductor and other fields, the cylinder is usually placed in the cylinder cabinet to use, the size of the cylinder cabinet and the connection of the pipe to determine the gas, the gas can not be arbitrary.

For different types of standard gas in the cylinder color, warning signs and other aspects of foreign countries have extremely detailed standards, such as the United States CGA, the EU ISO, etc., our country is still in this area is recognized and improved for the mixed gas Valve CGA, ISO also has its provisions. The chemical characteristics of the mixed gas is basically based on the LC50 calculation of the mixed gas as a basis for judging, and if we fail to support the series of standards, how can we meet the user's requirements for electronic mixed gas. At present, China's gas suppliers only according to the needs of a user to meet their specific needs, can not meet, the use of the so-called transition joints to achieve. This can meet the demand, but because the increase in leakage, no doubt is not conducive to safe use, so as soon as possible on the electronic mixed gas regulatory significance. Electronic standard gas cylinders In addition to the basic requirements of the above, the cleanliness of the inner wall is particularly important, otherwise, no matter how good the gas will be due to the pollution of the cylinder and come to naught. The concept of cleanliness of gas cylinders is still in the initial stage of our country, while foreign countries have three specific indicators for the treatment of cylinders: oxygen content, water content, particulate matter content, usually after the physical or chemical treatment of the cylinder dry After the ultra-pure helium, by measuring the indicators of ultra-pure helium to determine whether the cylinder to meet the requirements. There are many ways to deal with the inner wall of the cylinder. Sandblasting, deodorization, de-oiling, pickling and so on are the basic pre-methods. The other methods such as nickel plating and grinding are to deal with the inner surface, such as "SUPERUNIQUAL" Treatment method, the filling of PH3 0. 8% -He cylinder treatment, the cylinder wall roughness of 0. 8 μm below the particle content: 10 ps / cf (0. 1 μm at N2).