Line-type heat detectors operate by which mechanism?

Line-type heat detectors operate by which mechanism?

• A. Two steel conductors coated with a heat-sensitive polymer that melts away to allow contact
• B. A single sensor that detects a rapid rise in temperature
• C. Infrared detection of flame presence
• D. Acoustic sensing of heat waves

Answer: (A)

Line-type heat detectors work by using a fusible link between two conductors. The two steel conductors are coated with a heat-sensitive polymer that acts as an insulator. When the temperature reaches the detector’s rated level, the polymer melts away, allowing the conductors to touch and complete the circuit, which triggers the alarm. This physical melting contact mechanism is what distinguishes line-type detectors from other types, such as rate-of-rise detectors (which sense a rapid temperature increase on a single sensor), infrared flame detectors (which detect flame radiation), or acoustic sensing methods (not typically used for fire detection).

Line-type heat detectors work by using a fusible link between two conductors. The two steel conductors are coated with a heat-sensitive polymer that acts as an insulator. When the temperature reaches the detector’s rated level, the polymer melts away, allowing the conductors to touch and complete the circuit, which triggers the alarm. This physical melting contact mechanism is what distinguishes line-type detectors from other types, such as rate-of-rise detectors (which sense a rapid temperature increase on a single sensor), infrared flame detectors (which detect flame radiation), or acoustic sensing methods (not typically used for fire detection).