Adjustment Procedures Chapter 5
750-177 5-9
MODEL NO.
STD GAS
TRAIN SIZE
(IN.) Note 3
MIN. GAS
PRESSURE
(IN.W.C.)
Note 4
MIN. GAS
PRESSURE
(IN.W.C.)
Note 5
BURNER
MODEL
FLX-150 1 11.2 12.5 PFVG-15
FLX-200 1 19.4 21.7 PFVG-20
FLX-250 1.5 12.4 15.7 PFVG-25
FLX-300 1.5 15.9 20.7 PFVG-30
FLX-350 1.5 15.5 22.0 PFVG-35
FLX-400 1.5 18.7 27.2 PFVG-40
FLX-450 2 16.0 26.7 PFVG-45
FLX-500 2 17.6 21.0 PFVG-50
FLX-550 2 22.9 27.1 PFVG-55
FLX-600 2 20.0 24.9 PFVG-60
FLX-700 2 25.2 31.9 PFVG-70
FLX-800 2.5 19.9 22.2 PFVG-80
FLX-900 2.5 24.7 27.7 PFVG-90
FLX-1000 2.5 31.6 31.6 PFVG-100
FLX-1100 2.5 37.3 37.3 PFVG-110
FLX-1200 2.5 38.2 38.2 PFVG-120
Notes:
1. Table is based on 1,000 Btu/cu.ft natural gas and elevation to 1000
feet.
2. Minimum gas pressure also applies to 200 fuel series.
3. As an option, the standard gas train can be replaced with an
oversized design to reduce inlet gas pressure requirements.
4. Use this column for all U.S. Installations.
5. Use this column for all Canadian Installations.
T. FUEL OIL COMBUSTION
ADJUSTMENT
After operating for a sufficient period of time to assure a
warm boiler, adjustments should be made to obtain efficient
combustion.
Burner efficiency is measured by the amount or percentage of
O
2
present in the flue gas. O
2
readings determine the total
amount or excess air in the combustion process, above the
point of stoichiometric combustion or perfect combustion.
Stoichiometric combustion however, is the reference point
used when setting fuel/air ratios in a boiler.
There must always be excess air in the combustion process to
account for changes in boiler room conditions and to ensure
the combustion is on the proper side of the combustion curve .
Proper setting of the air/fuel ratios at all rates of firing must
be established by the use of a combustion gas analyzer.
Efficient combustion cannot be solely judged by flame
condition or color, although they may be used in making
approximate settings. Combustion settings should be done so
that there is a bright sharp flame with no visible haze.
Most flue gas analyzers in use today measure the content, by
percentage, of oxygen (O
2
) and in some cases, smoke.
Carbon dioxide (CO
2
) is not normally measured with modern
gas analyzers, but may be displayed as a calculation.
The O
2
levels through the entire firing range of the burner,
low fire to high fire should be tested. Cleaver-Brooks
recommendations on turndown should also be followed and
the turndown range of the burner should not be exceeded.
It is required to set the burner to operate with a reasonable
amount of excess air to compensate for minor variations in
the pressure, temperature, or burning properties of oil. Fifteen
to 20% excess air is considered reasonable. This would result
in an O
2
reading of 3% to 4%, at high fire.
REGULATOR INLET
PRESSURE (PSIG)
PRESSURE FACTOR
11.05
21.11
31.18
41.25
51.32
61.39
71.45
81.53
91.59
10 1.66
11 1.72
12 1.81
13 1.86
14 1.93
15 2.00
Table 6-2: Pressure Correction Factors
MODEL NO. 150 200 250 300 350 400 450 500 550 600 700 800 900 1000 1100 1200
Fuel Consumption Gas (cfh)
A
1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 7000 8000 9000 10000 11000 12000
A. Natural Gas @ 1000 Btu/cu-ft.
Table 6-1: Fuel Consumption (Natural Gas)
Table 6-3: Minimum Required Gas Pressures
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