20191053
20
GB
Installation
4.9.2
Gas train
Approved according to standard EN 676 and provided separately
from the burner.
4.9.3
Gas train installation
The gas train must be connected to the gas connection 1)(Fig.
22), using the flange 2), the gasket 3) and the screws 4) supplied
with the burner.
The train can enter the burner from the right or left side, depend-
ing on which is the most convenient, see Fig. 22.
4.9.4
Gas pressure
Tab. H indicates the pressure drops of the combustion head and
gas butterfly valve, on the basis of the burner operating output.
Tab. H
The values shown in Tab. H refer to:
–
natural gas G20 NCV 9.45 kWh/Sm
3
(8.2 Mcal/Sm
3
)
–
natural gas G25 NCV 8.13 kWh/Sm
3
(7.0 Mcal/Sm
3
)
Column 1
Combustion head pressure drop.
Gas pressure measured at test point 1)(Fig. 23), with:
•
combustion chamber at 0 mbar;
•
burner working at maximum modulating output;
•
combustion head set as on page 18.
Column 2
Pressure loss at gas butterfly valve 2)(Fig. 23) with maximum
opening: 90°.
To calculate the approximate output at which the burner oper-
ates:
–
subtract the combustion chamber pressure from the gas
pressure measured at test point 1)(Fig. 23).
–
Find, in Tab. H related to the burner concerned, the pressure
value closest to the result of the subtraction.
–
Read off the corresponding output on the left.
Example with natural gas G20:
Operation at maximum modulating output
Gas pressure at test point 1)(Fig. 23)
= 11.7 mbar
Pressure in combustion chamber
=
3 mbar
11.7 - 3
=
8.7 mbar
A pressure of 8.7 mbar (column 1) corresponds in Tab. H to an
output of 1300 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 1)(Fig. 23),
set the maximum modulating output required from the burner op-
eration:
–
find the nearest output value in Tab. H for the burner in ques-
tion.
–
read, on the right (column 1), the pressure at the test point 1)
(Fig. 23).
–
Add this value to the estimated pressure in the combustion
chamber.
DANGER
Disconnect the electrical power using the main
switch.
Check that there are no gas leaks.
Pay attention when handling the train: danger of
crushing of limbs.
Make sure that the gas train is properly installed
by checking for any fuel leaks.
The operator must use the required equipment
during installation.
Fig. 22
D722
kW
1
Dp (mbar)
2
Dp (mbar)
G 20
G 25
G 20
G 25
900
4.5
6.9
1.4
1.9
1000
5.5
8.6
1.8
2.3
1100
6.6
10.2
2.1
2.8
1200
7.7
11.8
2.5
3.4
1300
8.7
13.5
3.0
4.0
1400
9.9
15.2
3.4
4.6
1500
11.1
17.1
3.9
5.3
1600
12.5
19.4
4.5
6.0
1700
14.2
22.0
5.1
6.8
1800
16.3
25.3
5.7
7.6
1850
24.9
36.6
6.0
8.0
WARNING
The heat output and gas pressure data in
the head refer to operation with gas but-
terfly valve fully open (90°).
