🔍 Key Concepts

• Fire triangle: fuel, oxygen, and heat • Difference between flash point, fire point, and ignition temperature • Meaning of LEL (Lower Explosive Limit) and UEL (Upper Explosive Limit) for flammable vapors

💭 Think About

• Think about whether a solid or liquid actually burns, or whether it is the vapor above it that burns • Ask yourself: is having the right vapor/air mixture enough if there is no oxygen, or no heat? • Consider whether any one of the listed conditions alone is sufficient, or if all burning situations share more than one common requirement

✅ Before You Answer

• Verify what is required for the fire triangle to be complete • Check whether combustion can occur if the vapor/air mix is outside the LEL–UEL range • Confirm whether a substance can burn if it has heat and fuel, but no oxygen available