CleaverBrooks FLX 1000, Operation, Service And Parts Manual

Page: 27 / 136

LOW-HIGH-LOW MOD - LOW or 60% DAMPER PURGE
Combustion Air Gas Oil
COMPONENTS
DESCRIPTION:
A two blade damper is
controlled by a two position,
spring return actuator with
mechanical linkage. For 60%
damper purge a mechanical
stop is provided on the damper
to ensure sufficient air flow is
provided during prepurge.
Power to drive the actuator is
routed through a low/auto
switch and a remote located
modulating control. The
actuator also contains a limit
switch which is used to actuate
the second stage of the oil
supply system. (see oil at right).
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 linked
directly to the damper actuator
and provides gas flow metering
during the drive to the high
position. 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 the nozzle.
The oil pump has a built in solenoid controlled
two level pressure regulating system. Low and
high flow rates are set on the pump based on
pressure and the nozzle's flow
rating.
Operating Sequence
PRE-PURGE:
Damper is in its closed or low
fire position. For 60% damper
purge this would be against the
mechanical stop.
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 remains in its low fire
starting position.
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 low pressure setting.
Excess oil is flowing through an internal relief
valve and returning to the supply system.
RUN,
MODULATE:
Damper is driven open in 30
seconds by the two position
actuator. Low-High-Low
burners will modulate from the
low to high rate positions based
on the signal from the
modulating control and the
selection of the low/auto switch. The gas valves remain in their
open position. The actuator
begins it's travel to the high fire
position opening the gas metering
valve. The burner will then
modulate from low to high as
described in the combustion air
column.
The safety shut-off oil valves remain open. The
pump's solenoid is energized by the auxiliary
switch within the damper actuator as it opens
the air damper. Oil pressure is then increased
based the pumps high pressure setting. The
burner will then modulate from low to high as
described in the combustion air column.
SHUT DOWN,
POST-PURGE:
Damper returns to its start
position based on the 25
second closure speed of the
mechanical actuator. On shut down all gas valves close
within 1 second. The butterfly
valve closes in 25 seconds with
the two position actuator.
All valves immediately return to their startup or
de-energized 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: None None
For pumps without the internal dual pressure
solenoid an external pressure relief valve and
normally open solenoid valve are
used.
Profire V Burner Chapter 2
750-177 2-15