Installation
25
20096088
GB
4.13.2 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. 28), with:
•
combustion chamber at 0” WC
•
burner operating at maximum output
•
Combustion head adjusted as indicated in diagram (Fig. 19)
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. 28).
–
Find the nearest pressure value to your result in Fig. 28.
–
Read off the corresponding output on the left.
Example:
•
Maximum output operation
•
Natural gas
•
Gas pressure at test point 1)(Fig. 28)
= 5.04” WC
•
Pressure in combustion chamber
= 0.79” WC
5.0 - 0.79
= 4.21” WC
A maximum output of 4900 MBtu/hr shown in Fig. 27 corresponds
to 4.21” WC pressure, natural gas.
This value serves as a rough guide, the effective delivery must be
measured at the gas meter.
Tab. O
p
[
“WC
]
Fig. 27
Burner output
D11638
MBtu/h
p 1 (“WC)
p 2 (“WC)
3500
3.65
0.6
3800
3.7
0.7
4130
3.8
0.9
4430
3.9
1.0
4730
4.05
1.1
5030
4.25
1.3
5290
4.29
1.4
2
1
Fig. 28
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