A "chlorate candle", or an "oxygen candle", is a cylindrical chemical oxygen generator that contains a mix of sodium chlorate and iron powder, which when ignited smolders at about , producing sodium chloride, iron oxide, and at a fixed rate of about 6.5 man-hours of oxygen per kilogram of the mixture. The mixture has an indefinite shelf life if stored properly: candles have been stored for 20 years without decreased oxygen output. Thermal decomposition releases the oxygen. The burning iron supplies the heat. The candle must be wrapped in thermal insulation to maintain the reaction temperature and to protect surrounding equipment. The key reaction is: