Introduction
1-8
750-204
Profire D/LND
1. Air Compressor Module. Air is supplied by a positive displacement rotary vane compressor. This provides a
constant volume of atomizing air regardless of pressure. The compressor module includes motor, air-oil reser-
voir tank, air filter, and lube oil cooling coil. Air enters the compressor through the filter. The air flows from the
compressor into the air-oil separating and reservoir tank. Filtering material and baffles separate the lube oil
from the compressed air. The tank air pressure forces lubricating oil from the tank to the compressor to lubri-
cate bearings and vanes. A sight glass indicates the level of lubricating oil in the air/oil reservoir. Lubricating
oil must be visible in the gauge glass at all times. Air compression heat is absorbed in part by the flow of lube
oil, creating a hot oil mist. The air/oil mist is cooled by a coil assembly. Lube oil is also cooled before entering
the compressor.
2. Oil Metering. The oil metering unit is cored with channels through the housing. Fuel oil circulates through
these channels keeping the metering unit warm to prevent heavy oils from congealing when the burner is idle.
The operation of the oil metering unit is the same as the integral air/oil unit.
3. Operation. Fuel is delivered to the positive displacement metering pump at 10 to 15 psi. Metered oil is deliv-
ered to the common port of a 3-way solenoid valve for transfer to the burner nozzle through the normally
closed port or back to the storage tank through the normally open port. During pre- and post-purge, metered
oil is returned to the tank. During normal firing, all metered oil is delivered to the nozzle. Heavy oil burners
have a supplementary nozzle line heater between the metering and the 3-way valve. Air enters a rotary vane
compressor through an air cleaner where it is compressed to atomizing pressure. Air flows from the compres-
sor to an air/oil tank which serves the multiple purpose of dampening air pulsation, lube oil mist recovery,
lube oil and atomizing air storage. The compressor rotor is cooled and lubricated continuously by oil under
pressure from the air/oil tank. Oil vapor is extracted by a mist eliminator in the upper section of the tank.
Atomizing air from the upper tank section is delivered to the nozzle at a constant volume. Air pressure
increases as the burner firing rate increases. Atomizing pressure may be adjusted by the needle valve located
on the air-oil pump. The valve allows air to be bled from the tank to the compressor inlet. Delivery rate of the
fuel oil metering pump is controlled by the modulating motor through adjustable linkage.
FIGURE 1-6. Integral Oil-Air Metering System and Tank
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