PART III: OPERATION
27
Integrated proving system (burners equipped with LME7x, LMV, LDU)
Gas operation
Check the gas feeding pressure is sufficient (signalling lamp
G3
on).
Burners fitted with gas proving system:
the gas proving system test begins; when the test is performed the proving system LED
turns on. At the end of the test, the burner staring cycle begins: in case of leakage in a valve, the gas proving system stops the bur-
ner and the lamp
B1
turns on.
NOTE:
if the burner is fitted with Dungs VPS504, the pre-purgue phase starts once the gas proving system is successfully performed.
Since the pre-purgue phase must be carried out with the maximum air rate, the control box drives the actuator opening and when the
maximum opening position is achieved, the pre-purge time counting starts.
At the end of the pre-purge time, the actuator drives the complete closing (ignition with gas position) and, as this is achieved the
ignition transformer is energised (LED
B4
is on); the gas valves open.
Few seconds after the valves opening, the transformer is de-energised and lamp
B4
turns off.
The burner is now operating, meanwhile the actuator goes to the high flame position and, after some seconds, the two-stage ope-
ration begins; the burner is driven automatically to high flame or low flame, according to the plant requirements.
Operation in high or low flame is signalled by lamp
B2
on the frontal panel.
AIR FLOW AND FUEL ADJUSTMENT
Adjustments - brief description
Adjust the air and gas flow rates at the maximum output (“high flame”) first, by means of the air damper and the adjusting cam respec-
tively.
Check that the combustion parameters are in the suggested limits.
.Check the flow rate measuring it on the counter or, if it was not possible, verifying the combustion head pressure by means of a
differential pressure gauge.
Then, adjust the combustion values corresponding to the points between maximum and minimum: set the shape of the adjusting
WARNING! During commissioning operations, do not let the burner operate with insufficient air flow (danger of
formation of carbon monoxide); if this should happen, make the fuel decrease slowly until the normal combustion
values are achieved.
WARNING! the combustion air excess must be adjusted according to the values in the following chart.
Recommended combustion parameters
Fuel
Recommended (%) CO
2
Recommended (%) O
2
Natural gas
9 ÷ 10
3 ÷ 4.8
LPG
11 ÷ 12
2.8 ÷ 4.3
PS
EV1
EV2
/
EV2
EV1
PGCP
This paragraph describes the integrated proving system operation sequence:
At the beginning both the valves (EV1 and EV2) must be closed.
Test space evacuating: EV2 valve (burner side) opens and keep this position for a preset time
(td4), in order the bring the test space to ambient pressure.Test atmospheric pressure: EV2 clo-
ses and keep this position for a preset time (test time td1). The pressure switch PGCP has not to
detect a rise of pressure.
Test space filling: EV1 opens and keep this position for a preset time (td3), in order to fill the test
space.
Test gas pressure: EV1 closes and keep this position for a preset time (td2). The pressure switch
PGCP has not to detect a pressure drop down.
If all of the test phases are passed the proving system test is successful, if not a burner lockout
happens.
On LMV5x and LMV2x/3x and LME73 (except LME73.831BC), the valve proving can be parameteri-
zed to take place on startup, shutdown, or both. On LME73.831BC the valve proving is parameteri-
zed to take place on startup only.
