5
GAS PRESSURE
The adjacent tables show minimum pressure
losses along the gas supply line depending on
the maximum burner output operation.
Column 1
Pressure loss at combustion head.
Pressure of the gas at the socket 1)(B), with
combustion chamber at 0 mbar.
Column 2
Pressure loss at gas butterfly valve 2)(B) with
maximum opening: 90°.
Column 3
Pressure loss of gas train 3)(B) includes: adjust-
ment valve VR, safety valve VS (both fully
open), pressure governor R, filter F.
The values shown in the various tables refer to:
natural gas G 20 PCI 9.45 kWh/Sm
3
(8.2 Mcal/Sm
3
)
With:
natural gas G 25 PCI 8.13 kWh/Sm
3
(7.0 Mcal/Sm
3
)
multiply the values of the table:
- columns 1-2: by 1.5;
- column 3: by 1.35.
Calculate the approximate maximum output of
the burner in this way:
- subtract the combustion chamber pressure
from the gas pressure measured at test
point 1)(B).
- Find, in the table relating to the burner con-
cerned, the pressure value closest to the
result of the subtraction.
- Read the corresponding output on the left.
Example - RS 34/M MZ:
• Maximum output operation
• Natural gas G 20 PCI 9.45 kWh/Sm
3
• Gas pressure at test point 1)(B)
=8.5 mbar
• Pressure in combustion chamber
= 2 mbar
8.5 - 2 =6.5 mbar
A pressure of 6.5 mbar (column 1) corresponds in
the table RS 34/M MZ to an output of 240 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)(B), set the maximum output required
from the burner operation:
- find the nearest output value in the table for
the burner in question.
- Read, on the right (column 1) the socket pres-
sure 1)(B).
- Add this value to the estimated pressure in
the combustion chamber.
Example - RS 34/M MZ:
• Required burner maximum output operation:
240 kW
• Natural gas G 20 PCI 9.45 kWh/Sm
3
• Pressure of the gas at an output of 240 kW, from
the table RS 34/M MZ, column 1
=6.5 mbar
• Pressure in combustion chamber
= 2 mbar
6.5 + 2 =8.5 mbar
pressure required at test point 1)(B).
(A)
(B)
2
VS
VR
R
3
1
F
RS 34/M MZ
∆
p (mbar)
RS 44/M MZ
∆
p (mbar)
kW
1
2
3
MB 405
3970500
MB 407
3970553
MB 410
3970554
MB 412
3970144
MB 415
3970180
MB 420
3970181
3970182
125
0.3
0.1
14.7
8.0
4.2
2.2
3.2
3.2
150
0.9
0.1
20.6
11.3
5.7
2.9
3.2
3.2
200
2.0
0.1
32.8
18.2
9.1
4.5
3.2
3.2
250
3.1
0.2
46.8
26.4
13.2
6.5
3.8
3.2
300
4.3
0.3
36.9
18.1
8.7
4.9
3.4
350
5.9
0.4
48.2
23.0
11.3
6.1
4.3
390
7.1
0.6
57.5
27.1
13.5
7.1
5.0
kW
1
2
2
MB 407
3970553
MB 410
3970554
MB 412
3970144
MB 415
3970180
MB 420
3970181
3970182
200
0.8
0.1
18.2
9.1
4.5
3.2
3.2
250
1.8
0.2
26.4
13.2
6.5
3.8
3.2
300
2.8
0.3
36.9
18.1
8.7
4.9
3.4
350
3.9
0.4
48.2
23.0
11.3
6.1
4.3
400
4.9
0.6
28.3
14.1
7.4
5.2
450
6.1
0.7
34.0
16.9
8.7
6.1
500
7.5
0.9
40.0
19.9
10.1
7.0
550
9.0
1.1
45.9
23.2
11.6
8.2
D3790
Summary of Contents for 3788710
Page 1: ...END VALIDITY DATE 12 06 2007 ...
Page 64: ...20 RS 34 M MZ ...
Page 65: ...21 RS 44 M MZ 1Ph ...
Page 66: ...22 RS 34 44 M MZ 1Ph ...
Page 67: ...23 RS 44 M MZ 3Ph ...
Page 68: ...24 RS 44 M MZ 3Ph ...
Page 69: ...25 RS 34 44 M MZ 1Ph 3Ph ...
Page 70: ...26 RS 34 44 M MZ 1Ph 3Ph ...
