🔍 Key Concepts

• Fixed-temperature heat detectors vs. rate-of-rise detectors • How different actuating elements (fusible alloy, liquid, bimetallic strip/disc) respond to small, normal temperature fluctuations • Which designs are better at avoiding nuisance/false alarms from minor, brief overheating

💭 Think About

• Think about which detector type will react to very small temperature changes around its set point rather than requiring a clear, sustained over-temperature condition. • Which element is more likely to flex or move repeatedly with everyday temperature cycling (day/night changes, galley heat, sunlight on bulkheads)? • Compare how "snap-action" behavior differs from gradual bending or expansion in terms of triggering an alarm only when a definite threshold is reached.

✅ Before You Answer

• Identify which device is designed to move gradually with temperature rather than giving a sharp, definite snap at a set point. • Consider which design is least selective and may respond to minor, localized heating or drafts. • Ask yourself which detector type is generally considered more stable and resistant to nuisance trips in marine fire-detection systems, and rule those out.