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5.11.4 Gas pressure
The Tab. J indicates the pressure drop of the combustion head
and the gas butterfly valve depending on the operating output of
the burner.
The values shown in Tab. J refer to:
–
Natural gas G 20 NCV 9.45 kWh/Sm
–
Natural gas G 25 NCV 8.13 kWh/Sm
Column 1
Pressure drop on combustion head.
Gas pressure measured at the test point P1) (Fig. 18), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum modulating output;
•
Combustion head adjusted as in page 20.
Column 2
Pressure loss at gas butterfly valve 10) (Fig. 18) 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 P1) (Fig. 18).
–
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 RS 650/EV BLU with G20 natural gas:
Maximum modulating output operation
Gas pressure at test point P1)(Fig. 18)
Pressure in combustion chamber
28.6 - 5
A pressure of 23.6 mbar, column 1, corresponds in the table Tab.
J to an output of 4,500 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. 18),
set the maximum modulating output required from the burner op-
eration:
–
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. 18).
–
Add this value to the estimated pressure in the combustion
chamber.
Example for RS 650/EV BLU with G20 natural gas:
Maximum modulating output operation
Gas pressure at an output of 4,500 kW
Pressure in combustion chamber
23.6 + 5
Pressure required at test point P1)(Fig. 18).
Installation
3
3
(8.2 Mcal/Sm
)
3
3
(7.0 Mcal/Sm
)
= 28.6 mbar
=
5 mbar
= 23.6 mbar
= 23.6 mbar
=
5 mbar
= 28.6 mbar
23
GB
1 p (mbar)
kW
G 20
G 25
1,245
7.8
11.6
1,500
9.4
13.9
1,750
10.9
16.2
2,000
12.4
18.5
2,250
13.0
19.5
2,500
13.7
20.4
2,750
14.3
21.4
3,000
15.0
22.4
3,250
17.6
26.2
3,500
20.2
30.1
3,800
23.3
34.8
1,800
6.3
9.3
2,000
7.9
11.7
2,250
9.9
14.7
2,500
11.9
17.7
2,750
13.9
20.7
3,000
15.9
23.7
3,250
17.9
26.7
3,500
19.7
29.4
3,750
21.1
31.4
4,000
22.4
33.5
4,250
27.4
40.8
4,500
32.5
48.4
2,500
11.5
17.2
2,600
12.3
18.4
2,800
13.9
20.8
3,000
15.5
23.2
3,200
17.1
25.5
3,400
18.7
27.9
3,600
20.5
30.6
3,800
22.5
33.6
4,000
24.5
36.6
4,200
26.5
39.5
4,400
28.5
42.5
4,600
30.5
45.5
4,800
33.0
49.2
5,000
35.5
53.0
5,200
38.0
56.7
3,000
11.0
13.7
3,250
13.1
16.7
3,500
15.2
19.8
3,750
17.3
22.8
4,000
19.4
25.8
4,250
21.5
28.9
4,500
23.6
31.9
4,750
25.7
35.1
5,000
28.4
39.3
5,250
31.2
43.5
5,500
33.9
47.7
5,750
36.6
51.9
6,000
39.3
56.0
6,250
42.1
60.2
6,500
44.8
64.4
3,500
9.4
12.8
4,000
12.8
17.7
4,500
16.2
22.5
5,000
19.6
27.3
5,500
23.0
32.1
6,000
26.4
37.0
6,500
30.9
44.7
7,000
35.5
52.4
7,500
40.9
59.8
8,000
46.3
67.1
8,060
47.0
68.0
2 p (mbar)
G 20
G 25
1.3
2.0
1.9
2.8
2.6
3.9
3.4
5.0
4.3
6.4
5.3
7.9
6.4
9.5
7.6
11.3
8.9
13.3
10.3
15.4
12.2
18.2
2.9
4.3
3.5
5.3
4.5
6.7
5.5
8.2
6.7
10.0
8.0
11.9
9.3
13.9
10.8
16.2
12.4
18.6
14.2
21.1
16.0
23.8
17.9
26.7
0.6
0.8
0.6
0.9
0.7
1.0
0.8
1.2
0.9
1.4
1.0
1.5
1.2
1.7
1.3
1.9
1.4
2.1
1.6
2.3
1.7
2.6
1.9
2.8
2.0
3.1
2.2
3.3
2.4
3.6
1.0
1.5
1.1
1.7
1.3
2.0
1.5
2.3
1.7
2.6
1.9
2.9
2.1
3.3
2.4
3.7
2.6
4.0
2.9
4.5
3.2
4.9
3.5
5.4
3.8
5.8
4.1
6.3
4.5
6.8
0.6
0.7
0.7
0.9
0.9
1.1
1.2
1.4
1.4
1.7
1.7
2.0
2.0
2.3
2.3
2.7
2.6
3.1
3.0
3.5
3.0
3.5
Tab. J
20041914
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