Honeywell C7076D Product Data page 15

Single Burner System Using the C7076D Detector
WARNING
Fire or Explosion Hazard.
Can cause serious injury, death or property
damage.
Make sure that the environment surrounding the
C7076D is free of all explosive or hazardous
conditions before exposing the interior of the detector
to the atmosphere during the performance of the
following adjustment procedures.
1. Loosen the six screws in the rear cover plate of the
C7076D Detector and remove the plate.
2. Adjust Sensitivity Control A for maximum sensitivity.
a. If the remote sensitivity selection feature is used,
make sure the external selector switch is open for
Control A adjustment.
b. Turn Sensitivity Control A to MAX position.
3. Read the flame signal in microamperes at the Flame
Current jack.
a. Use a Honeywell W136A Test Meter with the
selector switch set at the SPL position. (If a W136A
is not available, a microammeter with a 0 to 25
microampere dc range, shunted with a 50
microFarad capacitor, may be used.
b. A 117053 Meter Connector Plug is needed (supplied
with the W136A or it may be ordered separately).
Connect the red spade tip to the red (+) meter lead
and the black spade tip to the black (-) meter lead.
See Fig. 17.
c. Insert the plug into the Flame Current meter jack
and allow a few seconds for the meter reading to
stabilize.
d. Read the average stable current, disregarding the
peaks due to shutter operation.
4. Optimize the flame signal.
a. Observe the flame signal while varying the line of
sight of the detector.
b. Adjust the angle and/or position of the sight pipe
(which was only tack welded as previously
instructed).
c. Try several sighting angles until you can obtain the
highest and most stable meter reading possible. (If it
is less than 1.4 microamperes, refer to the
Troubleshooting section).
d. Repeat step c for both the pilot and main burner
flame. Do not sacrifice the main flame signal to
obtain an unnecessarily high pilot flame signal.
5. Repeat steps 2 and 3 for Sensitivity Control B, if used.
Make sure the external selector switch is closed while
adjusting Control B.
6. Secure the swivel mount (if used) or tack weld the sight
pipe. Do not weld the sight pipe permanently into place
until you have completed the spark hold-in and pilot
turndown tests.
7. Remove the plug from the Flame Current meter jack.
8. Replace the rear cover plate on the detector. Ensure
that the tips of the sensitivity control extensions on the
rear cover are positioned properly to engage the slots of
the respective sensitivity controls on the rear of the
electronic chassis without altering their adjustments.
Reinstall the six screws in the cover plate and tighten
them securely.
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
Multiburner System Using the C7076D Detector
(Flame Discrimination)
1. Complete steps 1 through 8 under Single Burner
System above for each burner.
2. With all A sensitivity controls set to MAX position and all
burners firing at full load, select one burner and proceed
as follows:
a. Shut down the chosen burner, then note the flame
b. Gradually reduce the sensitivity by turning Control A
c. Relight the burner and note the flame signal
d. Repeat the run-shutdown-dropout procedures
NOTE: If the sensitivity control on a detector is reduced to
MIN position and flame discrimination cannot be
achieved, insert an orifice plate in the sight pipe. An
orifice of the proper diameter will reduce the
ultraviolet radiation reaching the detector so that the
sensitivity can be adjusted to effect flame
discrimination.
3. Repeat step 2 for Sensitivity Control A on each burner.
4. Repeat step 2 for Sensitivity Control B (if used) on each
burner. Verify that Sensitivity Controls A and B on each
detector are properly indexed by the system fuel selec-
tor, firing rate switch, etc.
Multifuel System
For multifuel systems use one sensitivity control for each fuel.
Follow steps 2 and 3 above for each fuel.
Ignition Spark Response Test
An ignition spark response test must be done for all detectors
to ensure that ignition spark will not actuate the flame relay in
the flame safeguard control The test is done by manually
closing all fuel valves, starting the system, and observing the
flame relay when the ignition comes on. If the flame relay pulls
in, the detector must be repositioned to eliminate the
response to ignition spark.
Pilot (Ignitor) Turndown Test
A pilot (ignitor) turndown test must be done for all applications
in which the detector must prove the pilot before the main fuel
valve can open. This test proves that the smallest pilot flame
which can hold in the flame relay (in the flame safeguard
control) is also capable of safely igniting the main burner. The
test consists of closing the main fuel valve, reducing the pilot
flame until it is just able to hold in the flame relay, and then
opening the main fuel valve to verify a safe main burner
lightoff.
Secure the Sight Pipe or Swivel Mount
1. When the flame signal is acceptable and all adjustments
have been made, remove the detector.
2. Secure the sight pipe (or swivel mount):
15
signal reading.
counterclockwise until the flame relay (in the flame
safeguard control) drops out.
reading. The difference between the new reading
and the initial reading in step a represents the
degree of flame discrimination.
(steps 2a-c) until the optimum setting has been
achieved.
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