"What goes around comes around" is particularly true for carbon dioxide (CO₂) as a refrigerant. In the late 1800s, CO₂ was used as a refrigerant in installations including chilling water and brines. It also was used for freezing and maintaining frozen products such as fish and meat. Manufacturers converted standard ammonia compressors to the high pressures required to condense CO₂ (ranging from 800 to 1,000 psi [5516 to 6895 kPa]). Of course, this limits the CO₂ system condensing temperature to 80°F or 85°F (27°C or 29°C), which is difficult to accomplish.