Which statement about flame detectors is true?

• A. They should NOT be installed in fully enclosed areas.
• B. They are usually in areas where other light sources are unlikely.
• C. They are NOT affected by natural light sources, such as sunlight.
• D. They respond to fires much more slowly than other types of detectors.

Answer: (B)

Flame detectors respond to the radiant energy emitted by flames, typically in ultraviolet or infrared wavelengths, so they provide a fast warning when a flame appears. Because they detect a flame signature rather than general light, they are usually placed in areas where other light sources are unlikely to cause false readings, which is why this statement is the best choice.

The idea that they are not affected by natural light sources isn’t accurate—bright daylight or other ambient radiation can cause false alarms in some flame detectors unless proper filtering is used. Also, flame detectors are designed to respond quickly to flames, not slowly, so claiming they react more slowly than other detectors isn’t correct. And installing them in enclosed areas can be appropriate where there’s a flame hazard, so saying they should not be used in enclosed spaces isn’t correct either.