according to the type of system (limiting potentiometer or
matching gas).
r.
Re-adjust the midfire points for the correct O2 levels.
The linkage may need to be readjusted to obtain the correct
relationship between the fuel valve and air damper. See
Figure F-1.
s.
If equipped with FGR, adjust the NOx levels at low and
midfire rates to be about 10% under the guaranteed levels
or as required for the gas firing.
t.
The burner should be operating at low fire to adjust the
air proving switch. Turn the adjusting screw cw (in) until the
burner trips out (shutdown caused by the air flow switch).
Turn the adjustment screw ccw (out) 1 ½ turns from the
point of shutdown. Check the operation at higher rates.
FIGURE F-3
Typical Atomizing Air and Oil Pressures
% Rate
Minimum
10
5 - 15
15
7 - 20
20
10 - 25
30
12 - 30
40
15 - 35
50
20 - 40
100
25 - 60
12. Operating Control Adjustments
The operating controls must be adjusted to properly cycle
the burner “ON and OFF” and provide modulation. See
Section E-11 for details. The controls should not force the
burner into rapid “ON-OFF” cycles, as this will cause pre-
mature failure of the motor and operating equipment.
The operating control must be adjusted to provide the “ON”
pressure or temperature desired. It must allow the burner
to come on and start before the temperature or pressure
drops into the modulating range. The “OFF” pressure or
temperature must be sufficiently above the “ON” point to
allow a reasonable run time.
The modulating control must be adjusted to start modula-
tion at some reasonable point below the “ON” temperature
or pressure and provide modulation to high fire at the lowest
temperature or pressure.
13. Limit Tests
Once the burner has been started and the operating pres-
sures and temperatures have been set, the limit switches
need to be adjusted so that they will trip if the pressure or
temperature exceeds the operating value, but will not trip
with normal variations. The switch should be checked for
proper operation by allowing the temperature or pressure
to vary below (or above) the recommended level to insure
that they provide safe shutdown before the burner operation
is affected. In some high pressure or temperature switch-
es, where the temperature or pressure cannot be set high
enough to trip the switch, the switch can be checked by
lowering the set point to prove that the switch will provide a
safe shutdown.
The limit switches would include the air proving switch
on the burner. Limits for gas operation could include the
high and low gas pressure switches and for oil firing, the
high and low oil pressure switches, high and low oil tem-
perature switches and the atomizing air pressure switch.
If in doubt about which limits are on a burner, refer to the
wiring diagram that will show each item.
Limit switches need to be checked at regular intervals
to ensure they are operating properly. See the mainte-
nance section for details.
14. Pilot Test
Once the burner as been set for the firing rates intended
for the burner, the pilot must be checked for proper op-
eration and safety.
The minimum pilot test is done to insure that a pilot which
can be seen by the scanner will light the main flame.
a.
During a startup sequence, measure the time re-
quired to light the main flame after the fuel valves have
been energized. This will be used to monitor the test
with reduced pilot.
b.
Lock the flame safeguard into the pilot position (refer
to the manual for the flame safeguard for this setting)
c.
Adjust the gas pressure regulator to the pilot for a
minimum value while still holding the minimum signal
strength for the scanner.
d.
Release the flame safeguard from the pilot position
and allow it to cycle though the main flame proving se-
quence.
e.
This reduced pilot must reliably light the main flame.
Monitor the time from the main fuel valve opening and do
not allow the burner to continue if the time is more then
an additional two to three seconds from the initial time
measured above.
f.
Run through two or three cycles.
g.
If this is a combination fuel burner, repeat the test on
the other fuel.
h.
Failures due to reduced scanner signal are also ac-
ceptable.
WARNING
THE MINIMUM PILOT TEST REQUIRES CLOSE SUPERVISION OF
THE COMBUSTION PROCESS. FAILURE TO CLOSELY MONITOR
THE MAIN FLAME TEST TIME COULD RESULT IN DAMAGE, IN-
JURY OR DEATH.
i.
If the pilot does not light the main flame under these
test conditions, check and adjust the pilot as shown in
figure E-1 and E-6.
The pilot must be tested for hot refractory pickup. This
test is performed to make sure that the scanner does not
see hot refractory that could be mistaken for a flame.
a.
After the burner has been operating for some time
at high input levels and the refractory in the vessel is
hot, the burner should be cycled off while monitoring the
scanner signal.
b.
The flame signal should drop off quickly as the flame
goes out and should be well below the minimum level
(indicating a flame) at the end of the post purge cycle.
Page 47
Section F - Startup and Operating Instructions
JBE(X) Manual
