The vacuum threshold at which fuel oil may break apart is measured in inches of mercury and is which value?

The vacuum threshold at which fuel oil may break apart is measured in inches of mercury and is which value?

• A. 8 inches
• B. 12 inches
• C. 10 inches
• D. 6 inches

Answer: (C)

Vacuum in inches of mercury is a way to express how strong a pump is pulling on a liquid. For fuel oil, there’s a practical limit: when the suction becomes too strong, the oil can break apart into unstable chunks or foam, which disrupts flow and atomization in the burner. That threshold is about 10 inches of mercury. So, at around 10 inHg of vacuum, fuel oil is at the point where it may start to break apart, making that value the correct reference. Keeping vacuum below this level helps maintain smooth flow and proper combustion.

Vacuum in inches of mercury is a way to express how strong a pump is pulling on a liquid. For fuel oil, there’s a practical limit: when the suction becomes too strong, the oil can break apart into unstable chunks or foam, which disrupts flow and atomization in the burner. That threshold is about 10 inches of mercury. So, at around 10 inHg of vacuum, fuel oil is at the point where it may start to break apart, making that value the correct reference. Keeping vacuum below this level helps maintain smooth flow and proper combustion.