Gas Pressure - Riello DB9 LSM C13 TC FB FS1 A0 T150 DUAL IGNITION Installation, Use And Maintenance Instructions

5.13.5 Gas pressure

Tab. I indicates the pressure drops of the combustion head and
gas butterfly valve, on the basis of the burner operating output.
The values shown in Tab. I 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 test point 1)(Fig. 25), with:
• combustion chamber at 0 mbar;
• burner working at maximum modulating output;
• combustion head set as on page 18.
Column 2
Pressure loss at gas butterfly valve 2)(Fig. 25) with maximum
opening: 90°.
To calculate the approximate output at which the burner oper-
ates:
– subtract the pressure in combustion chamber from the gas
pressure measured at test point 1) (Fig. 25).
– Find, inTab. I related to the burner concerned, the pressure
value closest to the result of the subtraction.
Read the corresponding output on the left.
Example DB12 LSM with natural gas G20:
Operation at maximum modulating output
Gas pressure at test point 1)(Fig. 25)
Pressure in combustion chamber
46.9 - 10
A pressure of 85.6 mbar (column 1) corresponds in Tab. I to an
output of 8000 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) (Fig. 25),
set the maximum modulating output required from the burner op-
eration:
– find the nearest output value in Tab. I for the burner in ques-
tion.
– read, on the right (column 1), the pressure at the test point 1)
(Fig. 25).
– Add this value to the estimated pressure in combustion
chamber.
Example DB12 LSM with natural gas G20:
Operation at maximum modulating output
Gas pressure at an output of 8000 kW
Pressure in combustion chamber
36.9 + 10
pressure required at test point 1)(Fig. 25).
Installation
3 3
(8.2 Mcal/Sm )
3 3
(7.0 Mcal/Sm )
= 46.9 mbar
= 10 mbar
= 36.9 mbar
= 36.9 mbar
= 10 mbar
= 46.9 mbar
23 GB
1 p (mbar)
kW
G 20 G 25
5000 16.0 23.2
5500 19.1 27.6
6000 22.1 32.0
6500 25.2 36.3
7000 28.9 41.6
7500 32.9 47.2
8000 36.9 52.7
8500 41.5 59.4
9000 46.4 66.3
9500 51.2 73.3
2 p (mbar)
G 20 G 25
1.8 2.7
2.2 3.3
2.6 3.9
3.1 4.6
3.6 5.3
4.1 6.1
4.7 7.0
5.3 7.9
5.9 8.8
6.6 9.8
Tab. I
20135492