Fire alarms. Automatic alarms also consist of two parts : a detecting part, and a signalling part (bell, buzzer, visual indicator, etc.). In addition to the automatic fire alarms, the heading also covers non-automatic alarms, such as are mounted in streets, for calling the fire brigade. Flame alarms (flame detectors) incorporating a photoelectric cell which operates the alarm through a relay when the flame lights or goes out.
Fire alarms incorporating smoke detectors containing a radioactive substance (heading 90.22)
Flame detectors not incorporating electric sound or visual alarm devices are classified in heading 85.36.