(a) Detectors must be responsive to heat, smoke, or other products of combustion, flame, or any combination of these factors. Detectors responsive to other indicators of incipient fires may be used if approved.

(b) Detectors must be capable of being triggered or tested and restored to service without the replacement of any component.

(c) Heat detectors must be rated not lower than 130 °F (54 °C) and not higher than 172 °F (78 °C). The operating temperature of heat detectors located in spaces of high normal ambient temperatures may be up to 260 °F (130 °C). The operating temperatures of heat detectors in saunas may be up to 284 °F (140 °C).

(d) Fire detectors fitted in passenger cabins must also emit, or cause to be emitted, an audible alarm within the cabin when activated.

(e) The required sensitivity and other performance criteria of detectors must be as set forth in 46 CFR 161.002.