750-368
CBEX Elite 100-1200 HP
2-7
2.7 — Automatic Ignition
2.7 — Automatic Ignition
Oil or gas burners are ignited by an interrupted type pilot. The pilot flame is ignited automatically by an electric
spark.
Burners are equipped with a gas burning pilot. In the case of a combination burner, the gas pilot is used to ignite
either the main gas flame or the oil flame.
At the beginning of the ignition cycle, and governed by the program relay and the Hawk control system, the pilot
solenoid valve and ignition transformer are simultaneously energized.
The ignition transformer supplies high voltage current for the igniting spark. A gas pilot has a single electrode and
a spark arcs between the tip of the electrode and the wall of the tube surrounding it. A light oil pilot has two elec-
trodes and the arc is between their tips. The pilot solenoid valve and the transformer are de-energized after main
flame is ignited and established.
Fuel for the gas pilot is supplied from the utility’s main, or from a tank (bottle) supply. Secondary air flows into
and mixes with the pilot gas stream to provide an adequate fuel and air mixture for combustion.
Insurance regulations may require two gas pilot solenoid valves with a normally open vent valve between them.
The vent valve closes when the gas pilot valves open, and opens when the gas pilot valves shut to vent gas,
should any be present in the pilot line during the de-energized period of the gas pilot valves.
2.8 — Atomizing Air
Air for atomizing the fuel oil (referred to as “primary” air) is pumped by the air pump into the air-oil receiver tank
and delivered under pressure through a manifold block to the oil burner nozzle.
The atomizing air mixes with the fuel oil just prior to the oil leaving the nozzle.
Atomizing air pressure is indicated by the air pressure gauge on the burner gun.
Air pressure from the pump also forces sufficient oil from the tank to the pump bearings to lubricate them and
also to provide a seal and lubrication for the pump vanes. As a result, the air delivered to the tank contains some
lube oil; however, most of it is recovered through baffles and filters in the tank before the air passes to the burner.
Some of the primary air is also used to assist the oil pressure regulators of the fuel oil controller. Further explana-
tion is given in Chapter 5.
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