Self-checking ultraviolet scanning capabilities make the Fireye 45UV5 ideal for continuously fired applications where recycling is infrequent or absent. These scanners can be used to detect ultraviolet emissions from fossil fuel flames such as natural gas, coke oven gas, propane, methane, butane, kerosene, light petroleum distillates, and diesel fuels. Self-checking circuit tests the electronics and the UV tube for proper operation every four seconds during the firing period. The Fireye 45UV5 also features a replaceable UV tube and shutter mechanism.