CleaverBrooks FLX Operation, Service And Parts Manual page 28

Chapter 2
PARALLEL POSITIONING
NOTE:
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.
COMPONENTS
A two bladed damper is
DESCRIPTION
controlled by an independent
parallel positioning actuator.
The remote mounted
modulating control
From its closed position the damper is
driven open by a signal from the parallel
PRE-PURGE
positioning control. The damper will
remain open for the duration of the pre-
purge cycle.
STARTUP,
Damper returns to the low fire position in
IGNITION
preparation for startup.
Damper
positioning actuator to a firing rate
position as determined by the parallel
RUN,
positioning control. The actuator and
MODULATE
parallel positioning control will then
continue to adjust the damper and fuel
actuators position based on signals from
remote sensors until demand is satisfied.
SHUT DOWN,
Damper returns to its closed position
POST-PURGE
during or following post purge.
Several parallel positioning
VARIATIONS
systems available. Consult the
factory for types and options.
2-16
Combustion Air
Parallel Positioning systems
is driven by its parallel
Gas
Safety shut off valve(s) are
provided to initiate the flow of
gas. The primary is
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.
Valves are closed.
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.
The gas valves remain in their open
position. The metering valve
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
combustion air heading until demand is
satisfied.
On shut down all gas valves close within
1 second. The butterfly valve returns to
it's starting position..
None
Profire V Burner
Oil
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
a parallel positioning actuator.
The pump is operational but the valves are
closed. Oil is flowing through an internal relief
valve and returning to the supply system.
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.
The safety shut-off oil valves remain open. The
and
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
the
described under the combustion air heading until
demand is satisfied.
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.
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
valve.
shut-off
750-177