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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.
14. Operating Control Adjustments
The operating controls must be adjusted to properly cycle
the burner "ON and OFF" and provide modulation. The con-
trols should not force the burner into rapid "ON-OFF" cycles,
as this will cause premature failure of the motor and operat-
ing 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 al-
low a reasonable run time.
The modulating control must be adjusted to start modulation
at some reasonable point below the "ON" temperature or
pressure and provide modulation to high fire at the lowest
temperature or pressure.
15. 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 low-
ering 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 temperature
switches and the atomizing air pressure switch. If in doubt
about which limits are on a burner, refer to the wiring dia-
gram that will show each item.
Limit switches need to be checked at regular intervals to
ensure they are operating properly. See the maintenance
section for details.
16. Pilot Test
Once the burner as been set for the firing rates intended for
the burner, the pilot must be checked for proper operation
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 required
to light the main flame after the fuel valves have been en-
ergized. This will be used to monitor the test with reduced
pilot.
b. Lock the flame safeguard into the pilot position (refer to
JB Manual
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
than 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.
THE MINIMUM PILOT TEST REQUIRES CLOSE SUPERVISION
OF THE COMBUSTION PROCESS.
MONITOR THE MAIN FLAME TEST TIME COULD RESULT IN
DAMAGE, INJURY OR DEATH.
i. If the pilot does not light the main flame under these
test conditions, check and adjust the pilot as shown in
section "H".
j. The infrared detector must be tested for hot refrac-
tory pickup. This test is performed to make sure that
the scanner does not see hot refractory that could be
mistaken for a flame.
k. 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.
h. 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.
i. The UV detector must be tested for spark pick-up.
Turn the burner on, with the pilot shut off, during the
ignition cycle the flame signal should be well below the
minimum level (indicating a flame).
j. If the flame signal does not drop out as required,
check the location of the pilot and scanner, as shown in
section "H". This may also indicate a faulty scanner or
amplifier.
17. Burner Shutdown
Normal operation of the burner will allow the operating
controls to shut the burner down when the load demand
is satisfied. If the burner needs to be shut down for any
reason, the "ON-OFF" switch can be used to quickly turn
the burner off. This will instantly cause the fuel valves
to close and start a post purge cycle to remove any un-
burned fuel from the vessel.
In an emergency shutdown, all fuel and electrical power
should be de-energized or turned off to secure the burn-
er. This would include the main power disconnect, the
manual gas shutoff valve at the drop down line and if
equipped, the manual oil valve to the nozzle.
Page 40
WARNING
FAILURE TO CLOSELY
Startup and Operating Adjustments
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