Customers who require large volumes of product in a continuous fashion can buy from or pay a monthly charge to Air Products for a cryogenic on-site system, which produces tonnage quantities of oxygen or nitrogen. Gases are produced by compressing air to such low, or cryogenic, temperatures that it liquefies and can then be separated into nitrogen and oxygen by distillation.

Gaseous oxygen plants supply up to 3000 MTD of product and are commonly used in the steel and chemical industries. They can also produce a small amount of liquid oxygen for peak periods or plant outages. Gaseous nitrogen plants are available as smaller standardized or packaged plants (up to 320 MTD) or as larger tonnage plants that produce between 320 and 3,300 MTD. Packaged plants supply the metals, electronics, glass and nuclear industries, while tonnage plants are commonly used for oil and gas recovery, ammonia synthesis, and natural gas Btu stabilization

Liquid-only cryogenic on-site plants produce large quantities of liquid oxygen, nitrogen, and argon, in volumes up to 1300 MTD. They typically supply merchant markets.