Adjustments And Checkout - Honeywell C7915A Information

C7915A INFRARED FLAME DETECTOR
ADJUSTMENTS AND
CHECKOUT
IMPORTANT:
Before welding the sight pipe in its final location, com-
plete the Adjustments and Checkout Tests below and
any tests required by the burner manufacturer.
ADJUST DETECTOR SIGHTING
POSITION
For initial burner light off, consult the burner manufacturer
instructions or flame safeguard control instructions.
With the flame detector installed and the burner running, adjust
the sighting position of the detector for optimum flame signal.
Refer to Table 6 for the minimum acceptable flame signal for
the amplifiers and associated flame safeguard controls.
The R7852B (AMPLI-CHECK™) amplifiers have a dc voltage
flame signal output.
To measure the flame signal voltage when using R7852A,B
amplifiers, a volt-ohm meter with a minimum sensitivity of one
megohm/volt is recommended. The flame signal (voltage)
measurements are made as shown in Fig. 12. The positive
(red) meter lead is connected to the positive (+) control jack
and the negative (black) meter lead to the negative (-)
-Com jack. If the 7800 SERIES, R7140 controls have the
Keyboard Display Module, a zero to five Vdc voltage is
displayed on the module. Refer to Table 6 for minimum and
maximum flame voltages.
Flame Signal Amplifier
R7852A
R7852B AMPLI-CHECK™
PILOT TURNDOWN TEST
If the detector is used to prove a pilot flame before the main
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
Test to be sure radiation from hot refractory does not mask the
flickering radiation of the flame itself.
65-0292-06
Table 6. Flame Signal.
Flame Safeguard Control
RM7800E,G,L,M; RM7823A; RM7838A,B,C;
RM7840E,G,L,M; RM7885A; RM7890A,B;
RM7895A,B,C,D; RM7896; RM7897;
RM7898; R7140
Move the detector and sight pipe around to sight the flame at
various positions and angles. Try to get a maximum steady
meter reading. The signal must be above the minimum
acceptable current/voltage listed in Table 6.
Measure the flame signal for 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 direct spark ignition). Also measure the
flame signal at high and low firing rates and while modulating in
between (as applicable). With the detector in its final position,
all required flame signals must be steady and as specified in
Table 6. If you cannot obtain the proper signals, refer to the
Troubleshooting section.
NEGATIVE (–)
METER LEAD
Fig. 12. Measuring 7800 SERIES, R7140 Flame Safeguard
Control flame signal voltage.
Minimum Acceptable
Steady Voltage (Vdc)
1.25
1.25
Start the burner and monitor the flame signal during the
warmup period. A decrease in signal strength as the refractory
heats up indicates hot refractory saturation. If saturation is
extreme, the flame signal will decrease to a point that 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 saturation is
eliminated.
10
POSITIVE (+)
METER LEAD
ONE MEGOHM/VOLT
METER
M7382A
Maximum Expected
Voltage (Vdc)
5.0
5.0