Fire extinguisher older models also achieved class B and C fire-fighting capability in the past, current models are rated A:K (Amerex, Ansul, Buckeye and Strike First) or K only (Badger/Kidde). Clean agents extinguish fire by displacing oxygen (CO or inert gases), removing heat from the combustion zone (Halotron-1, FE-36, Novec 1230) or inhibiting the chemical chain reaction (Halons). They are referred to as clean agents because they do not leave any residue after discharge which is ideal for protecting sensitive electronics, aircraft, armored vehicles and archival storage, museums, and valuable documents. Halon was completely banned in Europe and Australia except for critical
Fire triangle mechanically or chemically removing the fuel from the fire. Fuel separation is an important factor in wildland fire suppression, and is the basis for most major tactics, such as controlled burns. The fire stops because a lower concentration of fuel vapor in the flame leads to a decrease in energy release and a lower temperature. Removing the fuel thereby decreases the heat. Without sufficient oxygen, a fire cannot begin, and it cannot continue. With a decreased oxygen concentration, the combustion process slows. Oxygen can be denied to a fire using a carbon dioxide fire extinguisher, a fire blanket or water.