45UV5-1101 45UV5 SCANNER DIMENSIONS

Fireye Type 45UV5 scanners are self-checking, flame sensing devices. When powered by a

compatible, self-checking Fireye control, the scanners detect the presence or absence of flames which emit
ultraviolet radiation (UV). Typical fossil fuels which emit UV include natural gas, propane, methane,

butane, kerosene, light petroleum distillates and diesel fuels. For burners firing steam-atomized
oil or pulverized coal, Fireye recommends the use of infrared (IR) scanners. Fireye offers a complete
line of infrared scanners best suited for these applications.

When used with a Fireye amplifier, the 45UV5 scanner provides flame failure protection on single
and multi-burner industrial applications such as electric utility boilers, power boilers and large furnaces or incinerators. The

45UV5 scanner monitors the flame(s) of only one burner. The pilot and
main flames may be monitored individually (2 scanners) or in combination (1 scanner). When properly sighted, the

scanner should discriminate between the burner being monitored and all other burners and any background flames.

45UV5-1101

The 45UV5 scanner employs a detector which is a sealed, gas filled, ultraviolet-transmitting special
glass envelope containing two electrodes connected to an AC voltage source. The detector responds
only to a portion of the ultraviolet spectrum from common flames.
When ultraviolet radiation of sufficient energy (at wavelengths shorter than those in sunlight at the
earth’s surface) falls upon the electrodes, electrons are released and the inter-electrode gas becomes
conductive. This results in an electric current flow from one electrode to the other.
The current flow in the detector starts and ends abruptly and is known as an “avalanche.” A very
intense source of UV radiation will produce several thousand avalanches or pulses per second. Less
radiation will produce fewer pulses per second. Upon total loss of flame, the detector output ceases
except for very infrequent single pulses caused by cosmic rays. The circuitry does not respond to
these infrequent pulses. Thus, the presence or absence of pulses is an indication of the presence or
absence of flame; the frequency of the pulses is a measure of flame intensity. Pulses generated by the
scanner are transmitted to a compatible Fireye control via scanner wiring.