Honeywell 7800 SERIES Manual page 24

RM7890A,B,C
CHECKOUT
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, 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 longer
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 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, try lengthening the sight pipe or decreas-
ing 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 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. Start the burner and run through the PILOT IGN
period. Ignition spark should 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 further 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.
65-0126—2
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
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 operation,
check the Flame Failure Response Time (FFRT) and conduct
Safety Shutdown tests under all operating conditions.
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.
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 RM7890 reset pushbutton to restart the
system.
1. Detect flame 40 seconds after entry to STANDBY.
a. Simulate a flame to cause the flame signal voltage
level to be at least 1.25 Vdc for 30 seconds after the
intial 40 second entry into STANDBY.
b. Safety shutdown will occur.
2. Failure to ignite pilot.
a. Close the pilot and main fuel manual shutoff
valve(s).
b. Depress the reset pushbutton.
c. Start the system.
d. Automatic pilot valve(s) should be energized but
the pilot cannot ignite.
e. Safety shutdown will occur.
3. Loss of flame during RUN (if Flame Failure Action
configuration jumper, JR2, is selected for Lockout).
a. Open the main fuel manual shutoff valve(s). The
manual pilot shutoff valve(s) must also be opened.
b. Depress the reset pushbutton.
24