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Profire EV/LNEV Burner
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 eccen-
tric shaft and plate. The piston adjustment plate is posi-
tioned 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 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.
Separate Compressor Module
EV burners have a burner mounted oil metering unit and a
separate compressor module. The system functions as
follows:
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 reservoir 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
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lubricating oil from the tank to the compressor to lubricate
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.
Fuel is delivered to the positive displacement metering pump
at 10 to 15 psi. Metered oil is delivered 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. Air enters a rotary vane
compressor through an air cleaner where it is compressed to
atomizing pressure. Air flows from the compressor 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
Chapter 2
2-3
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