20044771
24
GB
Installation
4.9.3
Gas pressure
The diagram (Fig. 21) show minimum load losses at combustion
head depending on the maximum burner output operation with nat-
ural gas (G 20).
Gas pressure is measured at the test point 1)(Fig. 22), with:
•
Combustion chamber at 0 mbar
•
Burner working at maximum output
•
Ring nut 2)(Fig. 15) adjusted as in the diagram of Fig. 14
NOTE
To know the approximate output at which the burner is operating at
its maximum:
–
subtract the combustion chamber pressure from the gas pres-
sure measured at test point 1)(Fig. 22);
–
find, in the diagram (Fig. 21) the pressure value closest to the
result you want;
–
read the corresponding output on the left.
Example
•
Maximum output operation
•
Ring nut 2)(Fig. 15) adjusted as in the diagram of Fig. 14
•
Gas pressure at test point 1)(Fig. 22)
=
6.8 “wc
•
Pressure in combustion chamber
=
1.2 “wc
6.8 - 1.2
=
5.6 “wc
A maximum output of 8500 MBtu/hr corresponds to 5.6 “wc pres-
sure. This value serves as a rough guide; the effective output must
be measured at the gas meter.
NOTE
To know the required gas pressure at test point 1)(Fig. 22), set the
maximum output required from the burner operation, then:
–
find the nearest output value in the table for the burner in ques-
tion.
–
read, on the diagram (Fig. 21), the pressure test point 1)
(Fig. 22);
–
add this value to the estimated pressure in the combustion
chamber.
Example
•
Maximum output required: 8500 MBtu/hr
•
Ring nut 2)(Fig. 15) adjusted as in the diagram of Fig. 14
•
Gas pressure at output of 8500 MBtu/hr
=
5.6 “wc
•
Pressure in combustion chamber
=
1.2 “wc
5.6 + 1.2
=
6.8 “wc
pressure required at pressure test point 1)(Fig. 22).
Tab. H
p “WC gas butterfly 2)(Fig.22).
Fig. 21
Burner output operation
D10473
p (“WC)
MBtu/hr
kW
p “WC
4732
1387
0.60
5500
1612
0.82
6500
1905
1.18
7500
2198
1.57
8500
2491
2.00
9500
2784
2.50
10034
2941
2.79
Fig. 22
1
2
D2441
