Thermocouples are the most commonly used tool to monitor flare stacks. But these are contact type sensors, have relatively smaller design life and eventually fail over period of time due to harsh environment condition. Also, not being easily accessible due to their mounting location inside the stack, routine maintenance and quick replacements are difficult. UV Sensors detect a flame through its emitted ultra-violet energy. But they are less effective for flare monitoring as they need to be installed quite close to the stack. Otherwise they may detect UV energy from other sources, such as reflected sunlight and give false alarms. Also they can be blinded by smoke. Visual Cameras are often used as a low-end solution to visualize the flare in control room. But these are not at all suitable for smoky or foggy environment due to poor visibility. Further, the CCTV cameras cannot visualize those flames that are invisible to the naked eye.  Thermal camera recognizes the difference between the heat signature of a flare stack flame and the surrounding background (usually the sky or clouds). Even if the stack flame is invisible to the naked eye (or to a visual camera) because of its composition or low gas flow volume, a thermal camera can monitor whether a flare is burning or not.