"The red item in the foreground is a combination ultraviolet and infrared flame detector focused on a flammable liquid processing assembly. These special devices often are found in high hazard and high value operations such as refineries, drilling and production platforms, fuel loading facilities, compressor stations, electrostatic and paint spray booths, liquefied petroleum gas processing and storage facilities, aircraft hangars and chemical plants. They sense invisible energy at either end of the light spectrum that is emitted in the early stages of a fire."
Coffee Break Training - Fire Protection Series No. 2008-2
United States Fire Administration: http://www.usfa.fema.gov/