By David Hoskins • Updated March 24, 2022
The use of liquid oxygen has surged across diverse sectors—food preservation, medical therapy, and aerospace. Liquid air is obtained by cooling atmospheric air until it liquefies, and then applying fractional distillation to exploit the differing boiling points of its constituents. Below is a concise, expert‑approved protocol for extracting pure liquid oxygen, accompanied by essential safety guidance.
Filter the incoming air to eliminate dust and particulates. Cool the air in a staged process until it reaches –79 °C. At this temperature, carbon dioxide solidifies and is removed, leaving a mixture of nitrogen, oxygen, and argon.
Continue cooling until the mixture reaches –200 °C and fully liquefies.
Pump the liquid air into a fractionating column. Provide a controlled heat input at the base. As the temperature rises above –196 °C, nitrogen vaporizes, ascends, and is collected at the column’s top via a dedicated outlet.
Keep the column’s base temperature below –183 °C so that oxygen remains liquid. Withdraw the liquid oxygen from the bottom into a secondary column.
Apply gentle heating in the second column to raise the temperature until argon vaporizes. Separate the argon vapor and collect the remaining liquid oxygen into a storage vessel.
A central collection port in the fractionating column can capture argon, eliminating the need for a separate column.
Separating liquid oxygen from liquid air is inherently hazardous and must be performed only by trained professionals in compliant facilities. Liquid oxygen is a strong oxidizer that can cause severe frostbite upon contact and expands violently when warmed. Always wear appropriate protective gear and store the product in certified containers.
