A flame detector is a detector that uses optical sensors to detect flames.

Types

Ultraviolet

Ultraviolet (UV) detectors work with wavelengths shorter than 300 nm. These detectors detect fires and explosions within 3–4 milliseconds due to the UV radiation emitted at the instant of their ignition. False alarms can be triggered by UV sources such as lightning, arc welding, radiation, and sunlight.

Infrared

Infrared (IR) flame detectors work within the infrared spectral band. Hot gases emit a specific spectral pattern in the infrared region, which can be sensed with a thermal imaging camera (TIC) a type of thermographic camera. False alarms can be caused by by other hot surfaces in the area.

UV/IR

UV and IR flame detectors compare the threshold signal in two ranges and their ratio to each other to confirm the fire signal and minimize false alarms.

IR/IR flame detection

Dual IR (IR/IR) flame detectors compare the threshold signal in two infrared ranges.

IR/IR/IR flame detection

Triple IR flame detectors compare three specific wavelength bands within the IR spectral region and their ratio to each other to reliably detect flames and minimize false alarms.

Video

Closed-circuit television or a web camera can be used for video detection (wavelength between 0.4 and 0.7 µm). Like humans, the camera can be blinded by smoke or fog.

Applications

UV/IR flame detectors are used on hydrogen stations.

See also

• Active fire protection
• Flame ionization detector
• Gas leak detection
• Fire alarm system

References