Flame detectors are solutions for virtually any application where fire may result in a large loss of capital equipment and where risk to personnel is high. Industrial and commercial applications include oil and gas pipelines, turbine enclosures, off-shore platforms, automotive manufacturing facilities, aircraft hangers, munitions plants, nuclear facilities, and many, many more.
These systems use devices that respond to radiant energy visible to the human eye (approximately 4000 to 7000 angstroms) or to radiant energy outside the range of human vision [usually infrared (IR), ultraviolet (UV), or both]. Flame detectors are sensitive to glowing embers, coals, or actual flames with energy of sufficient intensity and spectral quality to initiate the detector.
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 thermo graphic camera. False alarms can be caused by other hot surfaces in the area. A typical frequency where single frequency IR flame detector is sensitive is in the 4.4 micro meter range. Typical response time is 3-5 seconds.
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. In order to reduce false alarms, a time delay of 2-3 seconds is often included in the UV Flame detector design.
Ultraviolet / Infrared Detection
UV and IR flame detectors compare the threshold signal in two ranges in "AND" configuration and their ratio to each other to confirm the fire signal and minimize false alarms.