Flame Scanners

• Flame scanners are used to detect whether a flame exists on a boiler
• Flame scanners are either
• UV
• Typically used for fuel gas applications
• IR
• Typically used for fuel oil/ coal fired applications
• Combination of UV/IR
• Most accurate
• Expensive
• Selection of UV/IR depends on the type of ray emitted during combustion process
• Flame scanners are typically powered by 24Vdc power supply.
• The old type flame scanner will normally come with a split rack panel which can accommodate several flame scanner cards. They are:
• Amplifier card
• Monitor flames, amplifier card, old technology,
• Scanner just detects radiation,
• 1 amplifier is for 1 scanner
• Some amplifiers have the option for 2 flame scanner connectivity to provide redundancy. I.e. 2 flame scanners can be connected to an amplifier card and declared as redundant to each other. A simple PLC logic can exist in the amplifier card
• Converts the signal to 4-20mA or relay output if require
• Power supply card
• Multi voltage, accept both 110VAC, 240VAC and changes it to 24V
• Gives a stable voltage since AC currents may effect reading
• 1 supply card will power multiple 24vdc flame scanners and amplifier cards
• Picture below shows a burner and flame scanners
• 
• Picture of Flame scanner rack for old technology flame scanner where the amplifier and power supply cards are separate. Picture on right is flame amplifier