2200 · 3 600
≈
34200 144 · 0,90
V=
Q · 3 600 =
H
u
· η
257,3 Nm
3
/h
V=
2200
≈
9,50 · 0,90
257,3 Nm
3
/h
273 + t
273
·
1013,25
B + P
u
273 + 15
273
·
1013,25
945 + 15
21
V = Gas volume Nm
3
/h
Q = Boiler output 2200 kW
H
u
= Calorific value of the gas A. 34,20 MJ/Nm
3
, B. 9,50 kWh/ Nm
3
η
= Expected efficiency 90%
Ex. A
Ex.
B
If the barometer height, pressure and temperature of the gas deviate
considerably from the normal values this must be taken into account as
follows:
f =
t = Temperature of the gas at the gas meter (15°C)
B = Barometer height (945 mbar)
P
u
= Pressure of the gas at the gas meter (15,0 mbar)
f =
f
≈
1.11
7. DETERMINATION OF GAS VOLUME FOR THE INSTALLATION
Specifications on natural gas, town gas and biogas vary. For more
exact information please contact the gas distributor.
Net calorific value H
u
15°C/1013,25 mbar
Gas quality
kWh/Nm
3
MJ/Nm
3
Natural gas
G20
9,50
34,20
Natural gas
G25
8,23
29,63
Propane
G31
24,41
87,88
Butane
G30
32,13
115,67
Biogas
6,00
21,60
7.1 Example how to calculate the gas volume (natural gas)
The gas volume read on the gas meter actually reads
1,11
.
257,3 = 285,6 m
3
/h.
