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4.13.3 Gas pressure
The adjacent diagram is used to calculate manifold pressure taking
into account combustion chamber pressure.
Gas manifold pressure measured at test point 1)(Fig. 27), with:
•
combustion chamber at 0 " WC
•
burner operating at maximum output
•
Combustion head adjusted as indicated in diagram (Fig. 26)
Calculate the approximate high fire output of the burner as follows:
–
subtract the combustion chamber pressure from the gas pres-
sure measured at test point 1)(Fig. 27).
–
Find the nearest pressure value to your result in Fig. 26.
–
Read off the corresponding output on the left.
Example with natural gas
•
Maximum output operation
•
Gas pressure at test point 1)(Fig. 27)
•
Pressure in combustion chamber
3.20 - 0.80
A maximum output of 2907 MBtu/hr shown in Tab. G corresponds
to 2.40" WC pressure, column 1, natural gas.
This value serves as a rough guide, the effective delivery must be
measured at the gas meter.
1 p ("WC)
MBtu/hr
1767
1957
2147
2337
2527
2717
2907
3093
20043127
= 3.20 "WC
= 0.80 "WC
= 2.40 "WC
2 p ("WC)
2.17
0.2
2.20
0.3
2.24
0.4
2.28
0.4
2.32
0.5
2.36
0.5
2.40
0.5
2.44
0.6
Installation
D11955
D10091
Tab. G
26
GB
Burner output
Fig. 26
1
2
Fig. 27
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