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21 20163413 GB
Installation
5.11.2 Gas train
Approved according to standard EN 676 and provided separately
from the burner.
5.11.3 Gas train installation
5.11.4 Gas pressure
Tab. J indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
The values shown in Tab. J refer to:
–
Natural gas G 20 NCV 9.45 kWh/Sm
3
(8.2 Mcal/Sm
3
)
– Natural gas G 25 NCV 8.13 kWh/Sm
3
(7.0 Mcal/Sm
3
)
Column 1
Pressure drop on combustion head.
Gas pressure measured at the test point P1) (Fig. 24), with:
•
Combustion chamber at 0 mbar;
• Burner working at maximum output;
• Combustion head adjusted as in page 19.
Column 2
Pressure loss at gas butterfly valve with maximum opening: 90°.
Calculate the approximate maximum output of the burner in this
way:
– subtract the combustion chamber pressure from the gas
pressure measured at test point P1) (Fig. 24).
– Find, in the table Tab. J related to the burner concerned, the
pressure value closest to the result of the subtraction.
– read the corresponding output on the left.
Example for with G20 natural gas:
Maximum output operation
A pressure of 25.6 mbar, column 1, corresponds in the table Tab.
J to an output of 5750 kW.
This value serves as a rough guide; the effective output must be
measured at the gas meter.
To calculate the required gas pressure at test point P1) (Fig. 24),
set the MAX output required from the burner operation:
–
find the nearest output value in the table Tab. J for the burner
in question.
– read, on the right (column 1), the pressure at the test point
P1) (Fig. 24).
– Add this value to the estimated pressure in the combustion
chamber.
Example for with G20 natural gas:
Required burner maximum output operation: 5750 kW
Pressure required at test point P1) (Fig. 24).
Tab. J
DANGER
Disconnect the electrical power using the main
system switch.
Check that there are no gas leaks.
Beware of train movements: danger of crushing of
limbs.
Make sure that the gas train is properly installed
by checking for any fuel leaks.
The operator must use appropriate tools for instal-
lation.
Fig. 24
P1 P4
20162147
Gas pressure at test point P1) (Fig. 24) = 27,6 mbar
Pressure in combustion chamber = 2 mbar
27,6 - 2 = 25,6 mbar
Gas pressure at an output of 5750 kW = 25,6 mbar
Pressure in combustion chamber = 2 mbar
25,6 + 2 = 27,6 mbar
WARNING
The heat output and gas pressure data in the
head refer to operation with gas butterfly valve
fully open (90°).
kW
1

p (mbar) 2

p (mbar)
G 20 G 25 G 20 G 25
3500 9.5 14.0 0.4 0.6
4250 14 20.6 0.6 1.0
5000 19.4 28.5 0.9 1.4
5750 25.6 37.7 1.2 1.8
6500 32.7 48.1 1.5 2.3
7250 40.7 59.9 1.9 2.9
8010 49.7 73.0 2.3 3.5