1-32 750-166
CB780/CB784
CHECKOUT
HOT REFRACTORY SATURATION TEST
(ALL INFRARED DETECTORS)
Test to make certain that radiation from hot refractory
does not mask the flickering radiation of the flame itself.
Start the burner and monitor the flame signal during the
warmup period. A decrease in signal strength as the refrac-
tory heats up indicates hot refractory saturation. If saturation
is extreme, the flame signal will drop below 1.25 Vdc and the
system will shut down as though a flame failure occurred.
If hot refractory saturation occurs, the condition must be
corrected. Add an orifice plate in front of the cell to restrict
the viewing area, lengthen the sight pipe or decrease the pipe
size (diameter). Continue adjustments until hot refractory
saturation is eliminated.
HOT REFRACTORY HOLD-IN TEST
(ALL INFRARED DETECTORS)
Test to make certain hot refractory will not delay the
flame detection system response to a flameout. This condi-
tion can delay response to flame failure and also can prevent
a system restart as long as hot refractory is detected.
Infrared (lead sulfide) detectors can respond to infrared
rays emitted by a hot refractory, even when the refractory has
visibly ceased to glow. Infrared radiation from a hot refrac-
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 ap-
plying 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 Burner
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) are
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 RE-
SPONSE 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 shut-off
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.
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 Flame Failure Response Time
(FFRT) and conduct Safety Shutdown Tests under all oper-
ating conditions.
FLAME SIGNAL WITH HOT COMBUSTION
CHAMBER (ALL INSTALLATIONS)
With all initial start-up tests and burner adjustments com-
pleted, operate the burner until the combustion chamber is at
the maximum expected temperature. Observe the equipment
manufacturer warm-up instructions. Recycle the burner un-
der these hot conditions and measure the flame signal. Check
the pilot alone, the main burner flame alone, and both
together (unless monitoring 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 3 sec-
onds maximum.
If the flame signal is too low or unsteady, check the flame
detector temperature. Relocate the detector if the tempera-
ture 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.
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