Gas Pressure - Riello RS 55/M BLU Instrucciones De Instalación, Uso Y Mantenimiento

5.9.3

Gas pressure

Tab. H indicates the minimum pressure drops along the gas sup-
ply line, depending on the maximum burner output.
1 p
Output
(kW) (mbar)
G20 G25
300 3.2 4.6
350 4.5 6.3
400 5.8 8.0
450 7.1 9.7
500 8.4 11.4
550 10.2 13.6
600 12.1 16.1
650 14.0 18.6
680 15.2 20.1
The values shown the table refer to:
– natural gas G 20 NCV 9.45 kWh/Sm
3
(8.2 Mcal/Sm )
– natural gas G 25 NCV 8.13 kWh/Sm
Column 1
Pressure drop on combustion head.
Gas pressure at test point 1)(Fig. 18), with combustion chamber
at 0 mbar;
Column 2
Pressure loss at gas butterfly valve 2) (Fig. 18) with maximum
opening: 90°.
Column 3
Pressure loss of gas train 3) (Fig. 18) includes:
• adjustment valve (VR)
• safety valve (VS) (both with maximum opening)
• pressure adjuster (R)
• filter (F)
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) (Fig. 18).
– Find, in the table Tab. H related to the burner concerned, the
pressure value closest to the result of the subtraction.
– Read off the corresponding output on the left.
Example:
Maximum output operation
Gas pressure at test point 1) (Fig. 18
Pressure in combustion chamber
14.1 - 2
A pressure of 12.1 mbar, column 1, corresponds in Tab. H to an
output of 600 kW.
This value serves as a rough guide; the effective output must be
measured at the gas meter.
Installation
2 p
(mbar)
3970144
G20 G25 G20
0.3 0.4 8.7
0.3 0.5 11.2
0.4 0.6 14.0
0.6 0.8 16.8
0.7 1.0 19.8
0.9 1.2 23.1
1.0 1.4 26.6
1.2 1.6 30.2
1.3 1.8 32.4
3
3 3
(7.0 Mcal/Sm )
) = 14.1 mbar
= 2 mbar
= 12.1 mbar
3 p (mbar)
3970180
G25 G20 G25
12.2 4.3 5.7
15.6 5.4 7.1
19.1 6.5 8.7
23.1 7.7 10.2
27.4 9.0 11.9
10.2 13.5
11.6 15.3
12.9 17.2
13.8 18.4
To calculate the required gas pressure at test point 1) (Fig. 18),
set the MAX output required from the burner operation:
– find the nearest output value in the table Tab. H for the burner
in question.
– read, on the right (column 1), the pressure at the test point 1)
(Fig. 18).
– Add this value to the estimated pressure in the combustion
chamber.
Example:
Required burner maximum output operation: 600 kW
Gas pressure at an output of 600 kW
Pressure in combustion chamber
Pressure required at test point 1) (Fig. 18).
3
VS
F
19 GB
3970146 3970181
3970160 3970182
G20 G25 G20
3.2 3.6 3.4
3.4 4.5 3.6
4.1 5.5 3.8
4.9 6.6 4.0
5.7 7.8 4.2
6.6 9.1 4.4
7.6 10.3 4.6
8.6 11.7 4.9
9.2 12.5 5.0
= 12.1 mbar
=
12.1 + 2 = 14.1 mbar
R
VR
D3790
G25
3.7
3.9
4.1
4.4
4.7
5.0
5.3
5.7
6.0
Tab. H
2 mbar
1
2
Fig. 18
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