Complex sentence: Prior to the introduction of concentrators, home medical oxygen systems had relied solely on compressed gas in heavy metal tanks and later in the 1970's and early 1980's on small medical oxygen cryogenic systems, also pioneered by Union Carbide, with stationary and ambulatory components.
Split into simpler sentences: Prior to the introduction of concentrators, home medical oxygen systems relied solely in the early days on compressed gas in heavy metal tanks. These cryogenic systems, also pioneered by Union Carbide, were available with stationary and ambulatory components.