Flame Monitoring And Measurement Of Ionisation Current; Adjustment Of Min. Gas Pressure Switch; Adjustment Of Max. Gas Pressure Switch; Adjustment Of Air Pressure Switch - Bentone bg 300 Manual

GENERAL INSTRUCTION

FLAME MONITORING AND MEASU-
REMENT OF IONISATION CURRENT
The burner is monitored according to
the ionisation principle. Check the io-
nisation current on start-up and on
each service call.
The reason for a low ionisation current
may be leaking currents, bad connec-
tion to earth, dirt or a faulty position of
the flame electrode in the burner head.
Sometimes also a faulty gas/air mixtu-
re may cause too weak a ionisation
current.
The ionisation current is measured by
means of a microampere meter (µA)
connected in series with the flame
electrode and the gas burner control.
Connect the µA-meter, see figure.
Min. required ionisation current ac-
cording to table. In practice this cur-
rent must be considerably higher, pre-
ferably more than 10 µA. All the gas
burners are equipped with a ionisation
cable that can be slit which facilitates
the connection of the µA-device.
GAS PRESSURE SWITCHES:
Adjustment range:
2,5-50 mbar GW 50
5-150 mbar GW 150
ADJUSTMENT OF MIN. GAS PRES-
SURE SWITCH
The min. pressure switch should react
if the gas pressure is too low and
prevent the burner from starting. Too
low a gas pressure during operation
should stop the burner. The burner
may start again when the rated gas
pressure has been reached.
Remove the protective cover. Connect
a pressure gauge for measuring the
rated pressure. Decide on pressure at
which the gas switch should switch off.
Set this pressure by means of the
valve. Carefully turn the knob (see
figure) until the gas pressure switch
switches off. The value shown on the
scale should then approximately cor-
respond with the value shown on the
pressure gauge. Tolerance on scale
appr. ± 15 %. Open the ball valve.
ADJUSTEMNT OF MAX. GAS PRES-
SURE SWITCH
The burner is equipped with a max. gas
pressure switch only on request. It
should stop the burner if the gas pres-
sure exceeds the set value. The burner
can then only be re-started manually
(gas burner control or overpressure
switch).
Remove the protective cover. Connect
a pressure gauge for measuring the
rated gas pressure. Decide on pres-
sure at which the gas pressure switch
should switch off. Turn the adjustment
knob to this value. Tolerance on the
scale ±15%.
Gas control
LMG
LGB
LFL
MMI 810
TMG 740-3
FLAME MONITORING
GAS PRESSURE SWITCH, AIR
PRESSURE SWITCH
ADJUSTMENT OF AIR PRESSURE
SWITCH
The air presure switch should stop the
burner if the air volume is reduced.
The air proving device shall be adjus-
ted in such a way that if there is
insufficient air supply at the highest or
lowest burner operating stage, the
device operates before the supervised
pressure is less than 80% of the pres-
sure at the controlled stage and the CO
content of the combustion products
exceeds 1% by volume.
AIR PRESSURE SWITCH:
Adjustment range ca:
1-10 mbar
2,5-50 mbar
Connection to terminal
in gas control
1
1
24
2
1
LGW 10
LGW 50
Min. ionisation
current required
2 µ A
10 µ A
10 µ A
5 µ A
5 µ A
172 305 25 00-01