Flammable liquids burn in presence of an ignition source and are easily ignited by heat, sparks, or flames. Which of the following is NOT a typical ignition method?

Flammable liquids burn in presence of an ignition source and are easily ignited by heat, sparks, or flames. Which of the following is NOT a typical ignition method?

• A. Heat
• B. Sparks
• C. Gravity
• D. Flames

Answer: (C)

Ignition of flammable liquids requires an energy source that raises the vapor-air mixture to its ignition energy. Heat, sparks, and flames all provide that energy, directly capable of starting combustion. Gravity does not supply ignition energy; it can influence how a spill or vapor moves—causing pooling or spreading—but it cannot ignite the liquid by itself. So gravity is not a typical ignition method.

Ignition of flammable liquids requires an energy source that raises the vapor-air mixture to its ignition energy. Heat, sparks, and flames all provide that energy, directly capable of starting combustion. Gravity does not supply ignition energy; it can influence how a spill or vapor moves—causing pooling or spreading—but it cannot ignite the liquid by itself. So gravity is not a typical ignition method.