7
GAS PRESSURE
Curves (to side) show gas pressure as a function
of the output generated by the burner in stage 2.
They represent the drop in pressure of the com-
bustion head.
The curve:
1 = Natural gas 420 PCI 10kWh/Nm
3
-8,60Mcal/Nm
3
absolute density
-0,71kg/Nm
3
2 = Natural gas 425 PCI 8,1kWh/Nm
3
-7,40Mcal/Nm
3
absolute density
-0,78kg/Nm
3
Curves were calculated under the following con-
ditions:
- Pressure measured at test point 13)(A)p.5
- Combustion chamber at 0 mbar
- Combustion head set as on page 9.
- Burner operating in stage 2
If the approximate output at which the burner is
operating in stage 2 must be known, record the
type of gas which was used, its pressure at test
point 13)(A)p.5 and the pressure in the combus-
tion chamber and then proceed as follows:
subtract combustion chamber pressure from gas
pressure and then refer to the graph correspond-
ing to the burner being considered.
Example:
• Burner GAS 9/2
• Natural gas PCI 10 kWh/Nm
3
(curve 1)
• Gas pressure at test point 13)(A)p.5 = 24 mbar
• Pressure in combustion chamber
= 2 mbar
24 - 2
= 22 mbar
in the GAS 9/2 graph, this corresponds to an out-
put in stage 2 of 1750 kW.
This reading is an initial approximation.
The effective delivery is be read at the meter.
If instead the gas pressure required at test point
13)(A)p.5
must be known, set the output at which
the burner is to operate in stage 2, record the
type of gas used and the chamber pressure and
then proceed as follows:
add the pressure in the combustion chamber to
the pressure indicated in graph (to side); both
pressures correspond to burner output in stage 2.
Example:
• Burner GAS 9/2
• Output required in stage 2: 2500 kW
• Natural gas PCI 10 kWh/Nm3 (curve 1).
• Gas pressure at output of 2500 kW,
• From GAS 9/2 graph
=26,2 mbar
• Pressure in combustion chamber
= 2 mbar
26,2 + 2
= 28,2mbar
is the pressure required at test point 13)(A)p.5
If the gas mains does not
permit the pressure indicated in
the graphs, open ring nut
2)(B)p. 9 by a further 1-2
notches.
(A)
S8057
WARNING
Summary of Contents for GAS 9/2
Page 2: ......
