Honeywell DVD Recorder L Manuale Utente

66-1153—03

32

If hot refractory saturation occurs, the condition must be 

corrected. Add an orifice plate in front of the cell to restrict the 

viewing area, lengthen the sight pipe or decrease the pipe 

size (diameter). Continue adjustments until hot refractory 

saturation is eliminated.

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.

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.

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.

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.

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.