750-204
Profire D/LND
1-7
1.8 — Oil System Air Atomizing
FIGURE 1-5. Integral Air/Oil Unit
1.8.9 — Air Compressor
Air is drawn into the vane-type, rotary compressor section of the air/oil unit through an air cleaner. The com-
pressed air flows to an air-lube oil tank which serves the multiple purpose of lube oil mist recovery, lube oil
sump, and air storage. The compressor is cooled and lubricated continuously by oil under pressure from the bot-
tom of the tank. Oil vapor is extracted from the compressor air by a mist eliminator in the upper section of the
tank. Atomizing air flows to the nozzle at a constant volume, but air pressure increases as the firing rate
increases. Atomizing air is regulated by an adjusting valve in the return air line on integral metering units or in the
air inlet on air compressor module burners.
1.8.10 — Oil Metering
Fuel oil under nominal pressure in the circulating loop, flows to the adjustable positive displacement, volumetric
metering unit. Oil metering is accomplished by changing the piston stroke by means of an eccentric shaft and pin
assembly. The pistons reciprocate in a rotor assembly, turning in a hardened steel sleeve having oil inlet and dis-
charge slots. During each revolution the pistons go through the following cycle:
1. Inlet Cycle. The piston is at the bottom dead center position. At this position the cavity between the top of the
piston and the outside diameter of the rotor fills with oil.
2. Discharge Cycle (180º from inlet cycle). The piston is at the top dead center position. At this position, the oil
is forced out of the discharge port to the nozzle. The piston stroke length is determined by the position of the
eccentric shaft and plate. The piston adjustment plate is positioned by an adjustable eccentric shaft. The
eccentric shaft is positioned by the modulator through adjustable linkage. Counterclockwise rotation of the
eccentric shaft increases the piston stroke (more oil delivered to the nozzle); clockwise rotation decreases the
amount of oil delivered. When the eccentric shaft is stationary, at any position, the stroke of the pistons
remains constant, delivering a constant volume of oil regardless of viscosity.
1.8.11 — Separate Compressor Module
All Models DE and DEG (also DL, DMG, DM, DMG 175-420) burners have a burner mounted oil metering unit
and a separate compressor module. The system functions as follows:
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