🔍 Key Concepts

• Fixed-temperature vs rate-of-rise heat detectors and how they operate • Which detector types rely on permanent physical change or destruction to operate • Which detector designs are mechanical and resettable vs one-shot devices

💭 Think About

• For each detector type, ask yourself: does it permanently deform, melt, or rupture when it trips, or can it go back to normal when cooled? • Think about which device is most likely to use a simple mechanical action (like bending or snapping) that can reset, rather than melting or breaking. • Eliminate any options that clearly involve melting, burning, or a chemical/physical change that cannot be reversed on board.

✅ Before You Answer

• Identify which option clearly involves melting metal and therefore cannot be reused. • Decide which options would likely be single-use safety elements (sacrifice themselves in a fire). • Pick the one option that works by mechanical movement of parts that can return to their original position after cooling.