Legal analysis: The industrial terminology of high-purity gas usually refers to a certain degree of purity that can be achieved through modern purification technology. For different kinds of gases, the purity index is different. For example, for nitrogen, hydrogen, argon and helium, it usually means that the purity is equal to or higher than 99.999%.

Legal basis: Catalogue of Encouraging Foreign Investment. Production and supply of large-scale, high-pressure and high-purity industrial gases (including electronic gases).