How much combustion air is required to burn one gallon of fuel oil?

• A. 500 cu ft
• B. 1540 cu ft
• C. 1000 cu ft
• D. 2000 cu ft

Answer: (B)

Combustion air is the oxygen supply required for the fuel to burn completely. For fuel oil, the typical air-to-fuel needs are such that, when you translate the stoichiometric amount of air into volume under standard conditions, about one and a half thousand cubic feet of air are needed to burn one gallon of fuel oil. This reflects the amount of oxygen necessary for complete combustion of the hydrocarbon in that gallon.

If there isn't enough air, combustion becomes incomplete, producing carbon monoxide and soot. If there’s too much air, flame temperature drops and efficiency decreases. In practice, burners are designed to supply a bit more air than the exact stoichiometric amount (excess air) to ensure complete combustion, but the standard reference figure used on tests is roughly one and a half thousand cubic feet per gallon of fuel oil.