C7015A
ADJUSTMENTS AND CHECKOUT
PILOT TURNDOWN TEST Ifthedetectorisusedtoproveapilotflamebeforethemain
fuel valve( can be opened, perform a Pilot Turndown Test before welding the sight pipe into position. Follow the procedures in the instructions for the appropriate flame safeguard control, and the burner manufacturer instructions.
HOT REFRACTORY SATURATION TEST Testtobesureradiationfromhotrefractorydoesnotmask
the flickering radiation of the l&me itself.
Start the burner and monitor the flame signal during the warmupperiod.Adecreaseinsignalstrengthastherefmctory heats up indicates hot refractory saturation. If saturation is extreme, the flame relay 2K (in the flame safeguard control) will drop out and the system will shut down as though a flame failure has occurred.
If hot refractory saturation occurs, the condition must be corrected. Add an orifice plate in front of the photocell to restrict the viewing area. If this does not work, resight the detector at a cooler, more distant background. Lengthening the sight pipe or decreasing the pipe size (diameter) may also be helpful. Continue adjustments until hot refractory satura- tion is eliminated.
HOT REFRACTORY HOLD-IN TEST
Test to make certain that hot refractory will not cause the flame relay 2K (in the flame safeguard control) to stay pulled- in after the burner flame is extinguished. This condition would delay response to flame failure and also would prevent a system restart as long as the infrared radiation emitted by the hot refractory is detected.
First check the plug-in flame signal amplifier by initiating a burner cycle. When the programmer stops in the run position, terminate the firing cycle while the refractory is at a low temperature. Measure the time it takes for the flame relay 2K to drop out after the flame goes out. Watch or listen to the flame relay to determine when it drops out. If the flame relay fails to drop out within four seconds, open the master switch and replace the amplifier.
Infrared detectors can respond to infrared radiation emit- ted by a hot refractory, even when the refractory has visibly ceased to glow. Infrared radiation from a hot refractory is steady, whereas radiation from a flame has a flickering characteristic.Theinliareddetectionsystemrespondsonlyto a flickering infrared radiation; it can reject a steady signal from hot refractory. However, the refractory’s 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 ensure its response to flame only.
To check a C7015A Inj-ared Flame Detector for hot refractory hold-in, operate the burner until the refractory reaches its maximum temperature. If the installation has a multifuel burner, burn the fuel most likely to reflect, bend, or obscure the hot refractory’s steady infrared radiation, (burn
solids instead of liquids, or liquids instead of gases.) When the maximum refractory temperature is reached, close all manual fuel shutoff valves or open theelectricalcircuit of all automatic fuel valves. Visually observe when the burner flame goes out. After the flame goes out, measure the time it takes for the flamerelay 2K to drop out. Watch or listen to the flame relay to determine when it drops out. If the flame relay fails to drop out within four seconds, the infrared detector is sensing theradiation from hot refractory. Immediately termi- nate the firing cycle, (lower the set point of the burner controller, or set the fuel selector switch to OFF). Do not open the master switch.
NOTE: Some burners continue to purge their oil lines be- tween the valves and nozzles 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 radiation, the
condition must bc corrected. Add an orifice plate in front of the photocell to restrict the detector viewing area. If this does not work, resight the detector at a cooler, more distant part of the combustion chamber. While resighting the detector, remember that it must also properly sight the flame. Length- ening the sight pipe or decreasing the pipe size (diameter) may also be helpful. For details, refer to Installation. Con- tinue adjustments until hot refractory hold-in is eliminated.
IGNITION INTERFERENCE TEST
It is possible for infrared amplifiers to respond to ignition spark electrical noise (interference) under certain conditions. Avoid ignition interference by locating the transformer as close as possible to the burner ignition electrode (preferably not on the control cabinet). You can also use an ignition cable that suppresses electrical noise (such as the type of cable used in automobiles). Maintain maximum separation of flame sensor and ignition wiring.
To determine if an infrared flame amplifier responds to ignition interference, complete the following test sequence:
1.CLOSE MANUAL FLJBL VALVES TO THE PILOT AND MAIN BURNER.
2.Connect a flame signal meter to the amplifier and start the burner.
3.There should be no flame signal when the ignitor is energized (momentary meter movement maybe observed when the flame safeguard control switches a load on or off).
WELD THE SIGHT PIPE
After adjustments have been made and an acceptable flame signal obtained, remove the detector and weld the sight pipe in its final position, (if you are using a swivel mount, the pipe may already be welded). Then reinstall the detector.
