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6.7.3
Gas train
Approved according to standard EN 676 and provided separately
from the burner.
To select the correct gas train model, refer to the supplied "Burn-
er-gas train combination" manual.
6.7.4
Gas train installation
Disconnect the electrical power using the main
switch.
DANGER
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.
The gas train is set up to be connected to the burner by the flange
2)(Fig. 8).
6.7.5
Gas pressure
Tab. E indicates the pressure drops of the combustion head and
gas butterfly valve, on the basis of the burner operating output.
Installation
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
The values shown in Tab. E refer to:
–
Natural gas G 20 NCV 9.45 kWh/Sm
–
Natural gas G 25 NCV 8.13 kWh/Sm
Column 1
Combustion head pressure drop.
Gas pressure measured at test point 1)(Fig. 18), with:
•
combustion chamber at 0 mbar;
•
burner working at maximum modulating output;
•
combustion head set as on page 21.
Column 2
Pressure loss at gas butterfly valve 2)(Fig. 18) with maximum
opening: 90°.
To calculate the approximate output at which the burner oper-
ates:
–
subtract the pressure in combustion chamber from the gas
pressure measured at test point 1) (Fig. 18);
–
find, in Tab. E related to the burner concerned, the pressure
value closest to the result of the subtraction;
–
Read off the corresponding output on the left.
Example DB 20 SM HS with natural gas G20:
Operation at maximum modulating output
Gas pressure at test point 1)(Fig. 18)
Pressure in combustion chamber
A pressure of 24.3 mbar, column 1, corresponds in Tab. E to an
output of 18000 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. 18),
set the maximum modulating output required from the burner op-
1
eration:
–
find the nearest output value in Tab. E for the burner in ques-
2
20112490
tion.
–
read, on the right (column 1), the pressure at the test point 1)
Fig. 18
(Fig. 18).
–
Add this value to the estimated pressure in combustion
chamber.
Example DB 20 SM HS with natural gas G20:
Operation at maximum modulating output
Gas pressure at an output of 18000 kW =
Pressure in combustion chamber
pressure required at test point 1)(Fig. 18).
19
GB
1 p (mbar)
kW
G 20
G 25
4.8
6.7
6.1
8.5
7.5
10.5
9.1
12.7
10.8
15.1
12.7
17.7
14.7
20.6
16.9
23.6
19.2
26.9
21.7
30.3
24.3
34.0
27.1
37.9
30.0
42.0
29.3 - 5
24.3 + 5
2 p (mbar)
G 20
G 25
2.2
3.2
2.8
4.1
3.5
5.0
4.2
6.1
5.0
7.2
5.9
8.5
6.9
9.8
7.9
11.3
9.0
12.8
10.1
14.5
11.3
16.2
12.9
18.1
4.0
20.0
Tab. E
3
3
(8.2 Mcal/Sm
);
3
3
(7.0 Mcal/Sm
).
= 29.3 mbar
=
5 mbar
= 24.3 mbar
24.3 mbar
=
5 mbar
= 29.3 mbar
20111775
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