After 1990s, the specifications of imported air separation unit increased to 20000m³/h and above, mostly from Linde and French Air Liquide, and also American Air Products. Foreign companies began to build manufacturing bases in China precisely because they were optimistic about the rapid development of China's national economy and the high market demand. After 1994, Linde and Air Liquide established large air separation plant manufacturing bases in Dalian and Hangzhou, Liaoning Province, re...