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2915858
Technical description of the burner
4.6 Firing rates
The burner output is selected from within the area of the dia-
grams.
This area is known as the FIRING RATE and provides the burner
output according to the pressure in the combustion chamber.
The work point may be found by plotting a vertical line from the
desired output and a horizontal line from the corresponding pres-
sure in the combustion chamber The intersection of these two
lines is the work point which must lie within the FIRING RATE.
Example:
for GAS 3 the area is delimited by:
• the axis of the 130 - 350 kW outputs
• the axis of the pressures in the comb. chamber 0 + 7 mbar
• the maximum pressure curve in comb. chamber
If the burner develops an output of 240 kW at a pressure in com-
bustion chamber of 5 mbar, the work point is found on the maxi-
mum pressure curve. This curve has been established with safety
margins and therefore it is possible to use the entire area of the
FIRING RATE beneath this curve.
The burner can also operate with the combustion chamber in de-
pression.
4.6.1 Minimum gas pressure - output
Pressure:
Detected at the pressure test-point 8) with mbar into the combus-
tion chamber.
Should the combustion chamber be pressurized, the pressure
necessary will be that of the graph plus the pressurization value.
Example:
To obtain 270 kW it is necessary a gas pressure of 8 mbar and
the combustion head set as indicated at page 9. If the combustion
chamber is pressurized at 2 mbar, the pressure detected at the
test-point 8) is: 8 + 2 = 10 mbar.
If this value is too high, for very low gas pipework pressures, the
gas gear 6) (page 9) could be more open. Do not decrease the
pressure at the coupling under the values shown in the diagram.
Output:
The maximum value is obtainable with gas Pci 8600 kcal/m
3
.
The firing rate value (Fig. 2) has been obtained
considering an ambient temperature of 20 °C, an
atmospheric pressure of 1,013 mbar (approx. 0 m
a.s.l.), and with the combustion head adjusted as
shown on page 16.
Pressure in combustion
chamber - mbar
Heat output
Fig. 2
20144735
KW
Mcal/h
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