Chapter 2 Profire V Burner
2-16 750-177
PARALLEL POSITIONING
Combustion Air Gas Oil
COMPONENTS
DESCRIPTION
NOTE: Parallel Positioning systems
incorporate independent actuators to
control each of the fuel and air metering
devices. Customizable "curves" can then
be created for each actuator to optimize
burner performance.
Safety shut off valve(s) are
provided to initiate the flow of
gas. The primary is a
diaphragm or motorized type
valve which have delayed
opening rates to prevent an "in
rush" of gas. A butterfly type
gas metering valve is directly
coupled to a parallel positioning
actuator. A manually adjusted
gas regulator limits maximum
firing rate.
Pressure Atomization: Two solenoid type safety
shut off oil valves initiate the flow of oil from the high
pressure pump to a return flow nozzle. In the return
line from the nozzle is an adjustable oil metering
valve which limits the amount of oil allowed to return
to the pump. The metering valve is direct coupled to
a parallel positioning actuator.
A two bladed damper is
controlled by an independent
parallel positioning actuator.
The remote mounted
modulating control
Operating Sequence
PRE-PURGE
From its closed position the damper is
driven open by a signal from the parallel
positioning control. The damper will
remain open for the duration of the pre-
purge cycle.
Valves are closed.
The pump is operational but the valves are
closed. Oil is flowing through an internal relief
valve and returning to the supply system.
STARTUP,
IGNITION
Damper returns to the low fire position in
preparation for startup.
Valves open. To prevent a surge the
primary gas valve opens at a slowed
rate. Gas flow to the manifold is metered
based on the butterfly valves low fire
setting.
Safety shut off valves open allowing oil to flow from
pump to nozzle. Oil pressure at the nozzle is based
on the pump's pressure setting less the volume of
oil returning through the metering valve.
RUN,
MODULATE
Damper is driven by its parallel
positioning actuator to a firing rate
position as determined by the parallel
positioning control. The actuator and
parallel positioning control will then
continue to adjust the damper and fuel
actuators position based on signals from
remote sensors until demand is satisfied.
The gas valves remain in their open
position. The metering valve and
actuator increases the flow of gas to the
manifold in conjunction with the opening
damper however, position adjustments
are made based on the fuel "curve"
stored in the parallel positioning control's
memory. The burner will continue to
modulate as described under the
combustion air heading until demand is
satisfied.
The safety shut-off oil valves remain open. The
metering valve and actuator decreases the flow of
oil returning to the pump in conjunction with the
opening damper however, position adjustments are
made based on the fuel "curve" stored in the parallel
positioning control's memory. This in turn is
increases the pressure and volume of oil at the
nozzle. The burner will continue to modulate as
described under the combustion air heading until
demand is satisfied.
SHUT DOWN,
POST-PURGE
Damper returns to its closed position
during or following post purge.
On shut down all gas valves close within
1 second. The butterfly valve returns to
it's starting position..
All valves immediately close. The metering valve
opens to it's low fire position. The oil pump is
operating with post-purge, but oil is flowing through
an internal relief valve and returning to the supply
system.
VARIATIONS
Several parallel positioning
systems available. Consult the
factory for types and options.
None
On models with a simplex nozzle oil is
diverted from the supply line through the
meter and back to the pump before the
first safety shut-off
valve.
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