Main Air Capacity,
Required Jet Air
§
Approx. Flame Lengths
Burner
Main Air
scfh at 16 osi
scfh at
with 16 osi Main Air
designation
pipe
size
†
Ambient
1000°F
8 osi
16 osi
Ambient
1000°F
4825-2
4"
2 560
1 420
50
—
2
½
2
4825-3
4"
3 990
2 370
70
—
2
½
2
4825-4
4"
6 150
3 930
145
—
2
½
2
½
4825-5
4"
10 600
6 450
165
—
2
2
½
4825-6
4"
16 700
10 050
—
155
5
3
½
4825-7-A
6"
27 400
17 100
—
175
5
4
4825-7-B
6"
34 100
21 000
—
275
5
½
4
½
4825-8-A
6"
44 200
27 900
—
450
5
½
4
½
† Smaller main air piping can be used in most cases. Use standard sizing methods for air temperature and pressure available. Minimum main air pressure
at the burner is 0.2 osi.
§ Ambient temperature jet air is required at all fi ring rates for burner stability and fl ame integrity.
4825 Burners will handle 1200°F preheated combustion air
fi ring car bottom, aluminum melting, forging, glass melting,
heat treating, and other furnaces where standard 4422 or 4425
Burners would be used if combustion air were not preheated.
Burners provide stable combustion in cold tight furnaces on
stoichiometric ratio, with large quantities of excess air, or on
moderately fuel-rich ratios. Air is evenly distributed around the
gas stream, creating uniform combustion and a well-defi ned
fl ame pattern throughout a wide turndown range.
Flames are clear to semi-luminous dependent on air tempera-
ture, fi ring rate, and air/fuel ratio.
CONTROL
Mass fl ow control systems with air temperature compensation
provide the most reliable fuel effi
ciency.
Fully metered fl ow control arrangements on the cold air side--
such as 7288 Regulators or 8096 Combustion Controllers--are
satisfactory for the vast majority of installations.
Because 4825 Burners are capable of lean starts on cold air,
standard cross connected regulators can be used on many batch
operations, as well as on continuous furnaces with constant
preheated air temperatures.
JET AIR
The burner uses a small amount of ambient air to insure good
fl ame thrust at low fi re. Some burners lose all discharge velocity
on applications that require wide turndown. Jet air on the 4825
solves that problem. Additionally, jet air cools internal parts
and prevents the cracking of fuel at low fi re caused by hot
combustion air.
Burner sizes -2 thru -5 require jet air at 8 osi pressure while
sizes -6 thru -8-A require 16 osi. Regardless of fi ring rate, jet air
fl ow is constant at about 2 percent of high-fi re air rate (ambient
temperature) for -5 and smaller burners, and 1 percent for -6 and
larger burners.
RECUPERATORS
4825 Burners are compatible with almost all recuperators,
including North American 8483, 8485, and 8486 units.
IGNITION/FLAME SUPERVISION
A 4011-12 pilot set is recommended for individual burner ignition.
When multiple burners share a single pilot pre-mix header, a
4021-12 pilot tip per burner with an appropriately sized air/gas
mixer is recommended.
For higher ambient temperatures specify a Honeywell C7035A
UV with an 8837-F Adapter, which includes a Honeywell heat
block #136733 (R130-5849) and a
¼
" fpt for 100 cfh cooling air.
CONSTRUCTION
Heat resistant cast iron burner bodies including air connections
are lined internally with vacuum-formed ceramic fi ber insulation.
Burner tiles are 3000°F castable with or without self- supporting
construction and are easily replaceable in the fi eld. Burner air
tubes, of high temperature alloy, are protected by a refractory
radiation shield.
Bulletin 4825
page 2
Product Overview | Hot Air Burners
