🔍 Key Concepts

• Fire tetrahedron – the four things a fire needs to keep burning • Difference between cooling, smothering, and chemical interruption of a fire • Typical use and effect of dry chemical (Purple K) and Halon systems

💭 Think About

• Think about which part of the fire tetrahedron these agents mainly affect: heat, fuel, oxygen, or the chemical chain reaction? • Compare these agents to water. Water mainly cools the fire – do Halon and Purple K work the same way or differently? • On ships, fixed Halon or similar gas systems are often used in machinery spaces. What are they designed to do to the burning reaction inside that closed space?

✅ Before You Answer

• Identify which option describes chemical interruption of combustion rather than just cooling or fuel removal • Recall that dry chemical agents like Purple K are known for stopping the combustion process very quickly • Verify whether these agents are primarily used for cooling, fuel removal, or stopping the reaction that keeps the fire going