Hot Refractory Hold-In Test (Rectifying Photocell, Infrared Detectors, Ultraviolet Detectors); Ignition Spark Response Test; Flame Signal With Hot Combustion Chamber (All Installations) - Honeywell R7140G Installation Instructions Manual

Hot Refractory Hold-in Test
(Rectifying Photocell, Infrared Detectors,
Ultraviolet Detectors)
This condition can delay response to flame failure and also
can prevent a system restart if 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 refractory
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 applying an
infrared system to verify its response to flame only.
The ultraviolet detector can respond to hot refractory above
2300°F (1371°C).
1. Operate the burner until the refractory reaches its
maximum temperature (Infrared Only). 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.
2. When the maximum refractory temperature is reached,
close all manual fuel shutoff valves, or open the
electrical circuits of all automatic fuel valves.
3. 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.
4. Immediately terminate the firing cycle. Lower the
setpoint 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 valves and nozzles even though the fuel valves
are closed. Terminating the firing cycle (instead of
opening the master switch) allows purging the
combustion chamber. This reduces a buildup of fuel
vapors in the combustion chamber caused by oil line
purging.
5. If the detector is sensing hot refractory, correct the
condition by one or more of the following procedures:
a. Add an orifice plate in front of the cell to restrict the
viewing area of the detector.
b. Resight the detector at a cooler, more distant part of
the combustion chamber. Make sure the detector
properly sights the flame.
c. 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.
R7140G,L,M BURNER CONTROL MODULES

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 shut-off
valve(s).
2. Start the burner and use the Run/Test Switch (if
available) 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 operating
manual and resight the detector farther out from the
spark, or away from possible reflection. It may be neces-
sary 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 and Q652B Solid State Spark
Generators prevent detection of ignition spark when
properly applied with C7027, C7035, C7044 or
C7061 Ultraviolet Flame Detectors. The Q624A and
Q652B are 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 daylight)
produce small amounts of ultraviolet radiation. Under certain
conditions, an ultraviolet detector responds 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 operating conditions.
Flame Signal With Hot Combustion Chamber
(All Installations)
1. With all initial start-up tests and burner adjustments com-
pleted, operate the burner until the combustion chamber
is at the maximum expected temperature.
2. Observe the equipment manufacturer warm-up
instructions.
3. 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.
4. Check the FFRT of the flame amplifier and relay module.
5. Lower the setpoint of the operating controller and observe
the time it takes for the burner flame to go out. This
should be within the maximum FFRT.
6. If the flame signal is too low or unsteady, check the flame
detector temperature. Relocate the detector if the temper-
ature is too high.
7. If necessary, realign the sighting to obtain the proper sig-
nal and response time.
8. If the response time is still too slow, replace the Plug-in
Flame Signal Amplifier.
9. If the detector is relocated or resighted, or the amplifier is
replaced, repeat all required Checkout tests.
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