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Appendix - Gas supply pressure
C
The adjacent tables show minimum load
losses along the gas supply line depending
on the maximum burner output operation.
Column 1
Load loss at combustion head.
Gas pressure measured at the test point
1)(Fig. 40), with:
• combustion chamber at 0 mbar;
• burner working at maximum output;
Column 2
Load loss at gas butterfly valve 2)(Fig. 40)
with maximum opening: 90°.
Column 3
Load loss at train 3)(Fig. 40) including:
adjustment valve VR, safety valve VS (both
fully open), pressure adjuster R, filter F.
The values shown in the tables refer to:
natural gas G 20 PCI 9.45 kWh/Sm
3
(8.2 Mcal/Sm
)
With:
natural gas G 25 PCI 8.13 kWh/Sm
3
(7.0 Mcal/Sm
) multiply the values of the
tables:
- columns 1-2: by 1.5;
- column 3: by 1.35.
To know the approximate output at which
the burner is operating at its maximum:
- Subtract the combustion chamber pres-
sure from the gas pressure measured at
test point 1)(Fig. 40).
- Find, in the table relating to the burner
concerned, column 1, the pressure value
closest to the result you want.
- Read the corresponding output on the left.
Example:
• Maximum output operation
• Natural gas G 20 PCI 9.45 kWh/Sm
• Gas pressure at test point 1)(Fig. 40)
• Pressure in combustion chamber
At a pressure of 5.4 mbar, column 1, a maximum output of 600 kW corresponds in the table RS 64/E MZ.
This value serves as a rough guide; the effective output must be measured at the gas meter.
To know the required gas pressure at test point 1)(Fig. 40), set the maximum output required from the burner operation, then:
- Find the nearest output value in the table for the burner in question.
- Read, on the right (column 1) the socket pressure 1)(Fig. 40).
- Add this value to the estimated pressure in the combustion chamber.
Example:
• Maximum output required: 600 kW
• Natural gas G 20 PCI 9.45 kWh/Sm
• Gas pressure at the output of 600 kW, of table RS 64/E MZ,
column 1
• Pressure in combustion chamber
gas pressure at test point 1)(Fig. 40).
20022445
RS 64/E MZ
kW
1
400
2.0
450
2.8
500
3.7
550
4.5
600
5.4
650
6.3
700
7.4
750
8.5
800
9.6
850 10.7 1.5
3
3
3
= 7.4 mbar
= 2.0 mbar
7.4 - 2.0
= 5.4 mbar
3
= 5.4 mbar
= 2.0 mbar
5.4 + 2.0
= 7.4 mbar
p (mbar)
2
Ø 3/4"
Ø 1"1/4
Ø 1"1/4
3970599
3970256
3970258
0.3
60.2
14.1
28.3
0.4
75.6
17.0
34.1
0.5
91.1
19.9
40.0
0.6
106.6
23.2
45.9
0.7
122.1
26.7
53.0
0.9
137.5
30.3
60.4
1.0
34.0
67.9
1.2
37.7
75.4
1.3
41.5
45.3
3
VS
R
F
52
GB
3
Ø 1"1/2
Ø 2"
3970250
3970252
3970221
7.4
5.2
8.8
6.1
10.1
7.0
11.6
8.2
13.2
9.5
14.7
10.8
16.4
12.1
18.0
13.4
19.9
14.8
21.8
16.3
1
VR
Ø 2"
DN 65
3970222
4.0
3.4
4.3
3.5
4.5
3.6
4.9
3.7
5.2
3.9
5.5
4.1
5.9
4.2
6.3
4.4
6.8
4.6
7.3
4.9
D3790
2
Fig. 40
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