Honeywell 7800 Series Manual page 30

RM7840E,G,L,M
CHECKOUT
tory is steady, but radiation from a flame has a flickering
characteristic. The infrared detection system responds only
to flickering infrared radiation; it can reject a steady signal
from hot refractory. The refractory steady signal can be made
to fluctuate if it is reflected, bent or blocked by smoke or fuel
mist within the combustion chamber. Be careful when apply-
ing an infrared system to verify its response to flame only.
To check infrared (lead sulfide) detectors for hot refrac-
tory hold-in, operate the burner until the refractory reaches its
maximum temperature. If the installation has a multi-fuel
burner, burn the heavier fuel that is most likely to reflect, bend
or obscure the hot refractory steady infrared radiation. When
the maximum refractory temperature is reached, close all
manual fuel shutoff valve(s), or open the electrical circuits of
all automatic fuel valve(s). Visually observe when the burner
flame or FLAME LED goes out. If this takes more than three
seconds, the infrared detector is sensing hot refractory.
Immediately terminate the firing cycle. (Lower the set point
to the operating controller, or set the Fuel Selector Switch to
OFF. Do not open the master switch.)
NOTE: Some burners continue to purge oil lines between the
valve(s) and nozzle(s) even though the fuel valve(s) is
closed. Terminating the firing cycle (instead of opening
the master switch) will allow purging the combustion
chamber. This will reduce a buildup of fuel vapors in the
combustion chamber caused by oil line purging.
If the detector is sensing hot refractory, the condition must
be corrected. Add an orifice plate in front of the cell to restrict
the viewing area of the detector. If this does not correct the
problem, resight the detector at a cooler, more distant part of
the combustion chamber. While resighting the detector, be
aware that it must also properly sight the flame. For an
infrared detector, try lengthening the sight pipe or decreasing
the pipe size (diameter). For details, refer to the detector
Instructions and the equipment Operating Manual. Continue
adjustments until hot refractory hold-in is eliminated.
ULTRAVIOLET SENSOR, IGNITION SPARK
RESPONSE TEST (ALL ULTRAVIOLET
DETECTORS)
Test to make certain that the ignition spark is not actuating
the FLAME LED:
1. Close the pilot and main burner manual fuel shutoff
valve(s).
2. Start the burner and use the Run/Test Switch to stop the
sequence in the PILOT IGN period. Ignition spark should
occur, but the flame signal should not be more than 0.5 Vdc.
3. If the flame signal is higher than 0.5 Vdc and the
FLAME LED does come on, consult the equipment operat-
ing manual and resight the detector farther out from the spark,
or away from possible reflection. It may be necessary to
construct a barrier to block the ignition spark from the
detector view. Continue adjustments until the flame signal
due to ignition spark is less than 0.5 Vdc.
NOTE: The Honeywell Q624A Solid State Spark Generator
will prevent detection of ignition spark when properly
applied with the C7027, C7035 or C7044 Minipeeper
Ultraviolet Flame Detectors. The Q624A is only for use
with gas pilots.
RESPONSE TO OTHER ULTRAVIOLET
SOURCES
Some sources of artificial light, such as incandescent or
fluorescent bulbs, mercury, sodium vapor lamps and day-
light, produce small amounts of ultraviolet radiation. Under
certain conditions, an ultraviolet detector will respond to
these sources as if it is sensing a flame. To check for proper
detector operation, check the FFRT and conduct Safety
Shutdown Tests under all operating conditions.
FLAME SIGNAL WITH HOT COMBUSTION
CHAMBER (ALL INSTALLATIONS)
With all initial start-up tests and burner adjustments
completed, operate the burner until the combustion chamber
is at the maximum expected temperature. Observe the equip-
ment manufacturer warmup instructions. Recycle the burner
under these hot conditions and measure the flame signal.
Check the pilot alone, the main burner flame alone, and both
together (unless monitoring only the pilot flame when using
an intermittent pilot, or only the main burner flame when
using DSI). Check the signal at both High and Low Firing
Rate positions and while modulating, if applicable.
Check the FFRT of the Flame Amplifier. Lower the set
point of the operating controller and observe the time it takes
for the burner flame to go out. This should be within .8 or 3
seconds maximum depending on the amplifier selected.
If the flame signal is too low or unsteady, check the flame
detector temperature. Relocate the detector if the temperature
is too high. If necessary, realign the sighting to obtain the
proper signal and response time. If the response time is still
too slow, replace the Plug-In Flame Signal Amplifier. If the
detector is relocated or resighted, or the amplifier is replaced,
repeat all required Checkout tests.
SAFETY SHUTDOWN TESTS
(ALL INSTALLATIONS)
Perform these tests at the end of Checkout, after all other
tests have been completed. If used, the external alarm should
turn on. Press the RM7840 reset pushbutton to restart the
system.
1. Opening a Preignition Interlock during STANDBY or
PREPURGE period. (Safety shutdown will occur.)
2. Opening a Lockout Interlock during PREPURGE,
PILOT IGN, MAIN IGN or RUN period. (Safety shutdown
will occur.)
3. Detection of flame 40 seconds after entry to STANDBY.
Detection of flame 10 seconds into Drive to Purge Rate for
RM7840E,L or 30 seconds for RM7840G,M or during mea-
sured PREPURGE time.
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