Honeywell 7800 Series Manual page 28

RM7885A
CHECKOUT
dition must be corrected as described in the last paragraph of
this test.
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 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 heaviest fuel that is most likely to reflect,
bend or obscure the hot refractory steady infrared radiation.
When the maximum refractory temperature is reached, press
the Stop Switch. If the FLAME LED takes longer than three
seconds after the flame goes out, the infrared detector is
sensing hot refractory. Do not open the master switch.
NOTE: Some burners continue to purge their 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 of 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. When using
an infrared detector, you can also 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 be sure that the ignition spark is not actuating the
FLAME LED:
1. Close the pilot and main burner manual fuel shutoff
valve(s).
2. Press the Start Switch. Ignition spark only will occur,
but the flame signal should not be more than 0.5 Vdc and the
FLAME LED should not turn on.
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.
4. Open the pilot and main burner manual fuel shutoff
valve(s).
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 Detector. The Q624A is only for use
with gas pilots.
RESPONSE TO OTHER ULTRAVIOLET SOURCES
Under certain conditions, an ultraviolet detector will
respond to other ultraviolet sources as if it is sensing a flame.
These ultraviolet sources include artificial light, such as
incandescent or fluorescent bulbs, mercury and sodium va-
por lamps, or daylight. To check for proper detector opera-
tion, check the Flame Failure Response Time (FFRT) and
conduct Safety Shutdown Tests under all operating condi-
tions.
FLAME SIGNAL WITH HOT COMBUSTION
CHAMBER (ALL INSTALLATIONS)
After all initial start-up tests and burner adjustments are
completed, operate the burner until the combustion chamber
is at the maximum expected temperature. Observe the equip-
ment manufacturer warm-up instructions. Recycle the burner
under these hot conditions and measure the flame signal.
Check the pilot alone for non-DSI applications or the main
burner flame for DSI applications.
Also check the FFRT. Press the Stop Switch 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.
1. Detect flame 40 seconds after entry to STANDBY for
a total time period of 30 seconds.
a. Simulate a flame to cause the flame signal voltage
level to be at least 1.25 Vdc for 30 seconds after
entry to STANDBY.
b. Press the Start Switch. No spark or pilot valve
should be energized.
2. Failure to ignite pilot.
a. Close the pilot and main fuel manual shutoff
valve(s).
b. Press the Start Switch.
c. Automatic pilot valve(s) and the spark should be
energized but the pilot cannot ignite.
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