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Note: From the above it can be seen that the choice of nozzles, depending on total capacity (2 nozzles working) desired,
must be made taking account of the capacities corresponding to a working pressure of 25 bar. Account must
therefore be taken of the fact that, when the burner is working with only the first flame on, the supply of fuel from
the first nozzle corresponds to the values shown in the table at 18 bar, because the pressure regulator for the
first flame is calibrated at this level. It is of course possible to vary, within wide limits, the relationship between
the first and the second flame by replacing the nozzles. You should however bear in mind that, for good running,
the fuel supply with the first flame should not be less than the minimum capacity (see the plate) for the specific
model. A lower capacity could make ignition difficult and combustion with only first flame may not be good. From
when the flame appears in the combustion chamber, the burner is commanded and controlled by the UV photo-
electric cell and the thermostats.
The regulator device (thermostat or pressure switch) for the boiler is enabled by opening an electrical contract and then
stopping the burner, when the value (temperature or pressure) it is adjusted to is reached. When the temperature or
pressure value has fallen below that necessary to cause reverse intervention of the regulating device (with closing of
the electrical contact), the burner is switched on again. If for any reason during working the flame goes out, (a second)
UV photo-electric cell acts to “lock out” the equipment (burner off – block light on). If the program stops, due to
interruption of electrical supply, manual intervention, thermostat triggered etc., during the pre-wash stage, the
programmer returns to its starting position and repeat all the burner ignition process.
HEAVY OIL PART GENERAL SCHEME
N° BT 8726/1
Return
Suction
Valve usually open
Air regulation servomotor
Valve usually open
1
5 bar valve
1
st
nozzle
2
nd
nozzle
22 bar valve
Filter
Pre-heater
Pressure regulator
18 bar (1
st
flame)
25 bar Pump
2
nd
flame
Bottom valve