In heat detector types, which must be replaced after activation?

In heat detector types, which must be replaced after activation?

• A. Fixed Temperature
• B. Line Detectors
• C. Spot Detectors
• D. Photoelectric

Answer: (A)

Fixed-temperature heat detectors use a fusible element or glass bulb that melts or ruptures when the ambient temperature reaches the preset point. That element is permanently altered by the activation, so the detector cannot be reset to its original state. Because of that, the entire unit must be replaced after it has triggered. Other heat detector types work differently. Rate-of-rise detectors respond to a rapid temperature increase with a bi-metallic element that can reset after cooling, so they don’t inherently require replacement after a single activation. Line and spot detectors are installation formats and may be reset or serviced rather than simply replaced due to activation. Photoelectric devices are used for smoke detection, not heat, so they aren’t the type that would be activated and replaced in the same way.

Fixed-temperature heat detectors use a fusible element or glass bulb that melts or ruptures when the ambient temperature reaches the preset point. That element is permanently altered by the activation, so the detector cannot be reset to its original state. Because of that, the entire unit must be replaced after it has triggered.

Other heat detector types work differently. Rate-of-rise detectors respond to a rapid temperature increase with a bi-metallic element that can reset after cooling, so they don’t inherently require replacement after a single activation. Line and spot detectors are installation formats and may be reset or serviced rather than simply replaced due to activation. Photoelectric devices are used for smoke detection, not heat, so they aren’t the type that would be activated and replaced in the same way.