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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
–
Natural gas G 25 NCV 8.13 kWh/Sm
Column 1
Combustion head pressure drop.
Gas pressure measured at the test point P1)(Fig. 21), with:
•
Combustion chamber at 0 mbar;
•
Burner working at maximum output;
•
Combustion head adjusted as in page 22.
Column 2
Pressure loss at gas butterfly valve 4)(Fig. 31 on page 29) 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. 21).
–
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 410/M BLU with G20 natural gas:
Maximum output operation
Gas pressure at test point P1)(Fig. 21)
Pressure in combustion chamber
A pressure of 53.1 mbar, column 1, corresponds in the table Tab.
J to an output of 4450 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. 21),
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. 21).
–
Add this value to the estimated pressure in the combustion
chamber.
Example for RS410/M BLU with G20 natural gas:
Required burner maximum output operation: 4450 kW
Gas pressure at an output of 4450 kW
Pressure in combustion chamber
53.1 + 5
Pressure required at test point P1)(Fig. 21).
3
(8.2 Mcal/Sm
3
(7.0 Mcal/Sm
= 58.1 mbar
=
5 mbar
58.1 - 5
= 53.1 mbar
= 53.1 mbar
=
5 mbar
= 58.1 mbar
Installation
kW
1200
1440
3
)
3
1690
)
1930
2170
2420
2660
2900
3140
3390
3630
1500
1800
2090
2380
2680
2980
3270
3560
3860
4160
4450
1800
2140
2490
2840
3180
3520
3870
4220
4560
4900
5250
2200
2600
3010
3420
3820
4220
4630
5040
5440
5840
6250
25
GB
1 ∆ p (mbar)
2 ∆ p (mbar)
G 20
G 25
G 20
23.1
34.5
0.1
23.6
35.2
0.5
24.1
36.0
1.1
24.6
36.7
2.1
25.1
37.4
3.1
26.7
39.8
4.2
29.6
44.2
5.3
33.4
49.8
6.4
38
56.7
7.6
43.7
65.2
8.8
50.1
74.7
10
2.6
3.9
0.3
7.1
10.6
1.5
11.5
17.2
2.8
16.1
24.0
4.0
21.1
31.5
5.4
26.1
38.9
6.8
31.2
46.6
8.2
36.3
54.2
9.6
41.9
62.5
11.2
47.5
70.9
12.7
53.1
79.2
14.3
14.0
20.9
1.5
15.5
23.1
3.0
17.8
26.6
4.5
20.7
30.9
6.1
24.2
36.1
7.8
28.3
42.2
9.4
33.3
49.7
11.2
39.0
58.2
13.0
45.2
67.4
14.9
52.0
77.6
16.8
59.7
89.1
18.8
9.3
13.9
3.3
13.6
20.3
5.0
18.6
27.8
7.0
24.1
36.0
8.9
30.1
44.9
11.0
36.5
54.5
13.0
43.7
65.2
15.3
51.5
76.8
17.6
59.6
88.9
19.9
68.2
101.8
22.3
77.6
115.8
27.8
G 25
0.1
0.7
1.6
3.1
4.6
6.3
7.9
9.5
11.3
13.1
14.9
0.5
2.2
4.2
6.0
8.1
10.1
12.2
14.3
16.7
18.9
21.3
2.2
4.5
6.7
9.1
11.6
14.0
16.7
19.4
22.2
25.1
28.0
4.9
7.5
10.4
13.3
16.4
19.4
22.8
26.3
29.7
33.3
37.0
Tab. J
20075006
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