liquidoxygen

Liquid oxygen is the liquid phase of molecular oxygen, prepared from air by fractional distillation. It is a pale blue liquid at cryogenic temperatures, highly oxidizing, and significantly denser than air.

Physical properties include a boiling point of −183°C (90 K) at one atmosphere. It freezes at around −218°C. In its liquid form, oxygen is paramagnetic and acts as a strong oxidizer, supporting combustion vigorously.

Production and storage involve fractional distillation of clean air in air separation plants. Liquid oxygen is transported and stored in insulated cryogenic dewars designed for oxygen service, with venting to release boil-off gas to maintain pressure. All materials used in oxygen systems must be compatible to avoid accidental ignition sources.

Uses include its role as an oxidizer in rocket propulsion (often paired with RP-1 or hydrogen), medical oxygen therapy, and industrial processes such as steelmaking, metal cutting, and welding.

Safety considerations emphasize cryogenic hazards and the risk of asphyxiation in enclosed spaces due to displacement of ambient air. Oxygen-enriched environments can dramatically increase the tendency of materials to ignite or explode when contaminated with fuels or oils. Handling and storage require oxygen-compatible equipment, proper procedures, and training to prevent ignition sources and cold burns from contact with liquid oxygen.