What is the flash point of #6 fuel oil?

• A. 140 degrees F
• B. 120 degrees F
• C. 100 degrees F
• D. 180 degrees F

Answer: (A)

Flash point is the lowest temperature at which a liquid’s vapors can form an ignitable mixture with air. For heavy fuels like #6 fuel oil, you need to heat the oil more before its vapors can ignite, so the flash point sits relatively high. The standard value listed for #6 fuel oil is about 140 degrees Fahrenheit, making it less likely to ignite at typical room temperatures than lighter fuels. The other numbers don’t match the usual specification for this fuel—100 and 120 are too low for a heavy oil, and 180 is higher than the common rating. So 140 degrees Fahrenheit is the correct flash point.