North American Dual-Fuel
™
Hot Spot Burners
Sheet 6841
Dual-Fuel
™
Hot Spot Burners produce short, intense, concentrated fl ames on gas or distillate oil. Two sizes are available -- 6841-7, which uses 20 osi
atomizing air, and 6841-8-B25, which uses 15 psi compressed air for atomization. Excellent turndown characteristics of the 6841-8-B25 permits its use
over the capacity range normally served by -8-A and -8-B burners. Use of atomizing air during gas operation permits equal capacity on gas or oil. If
reduced gas capacity is acceptable for the 6841-8-B25, compressed air can be reduced to 1 psig (minimum to prevent atomizer overheating). The
6841-7 is stable in a cold, tight chamber. Do not run it rich on oil.
6841-7 Burners have 13
½
" square by 9" (nominal) long tiles. 6841-8-B25 Burners have 24" diameter grooved tiles. Tiles are of refractory material
suitable for 3000°F tile temperature. Tile cover plates are heat-resisting cast iron. Burner internals that see fl ame are alloy.
Required gas pressure
at the burner connection is 3 osi for 6841-7 and 1.5 osi for 6841-8-B25.
Pilots, 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. Pilot Tips use 6"wc mixture pressure. Flame rods or
UV detectors work satisfactorily with pilot and main gas fl ames. For monitoring oil fi res, only UV is satisfactory--fl ame rods tend to collect carbon. For
satisfactory operation, UV detectors must be purged with air. Flame detectors must be installed clockwise of pilot as viewed from rear of burner.
Total Capacities.
Gas capacity is based on 0.6 sp gr, 1000 Btu/ft
3
gas, using main and full atomizing air. Oil capacity is based on #2 oil at 140 000
Btu/gallon.
Burner
designation
Air, scfh
Gas, scfh
Oil, gph
Air, scfh
Gas, scfh
Oil, gph
6841-7
22 100
2210
15.8
25 200
2520
18.0
6841-8-B25
57 600
5760
41.1
66 500
6650
47.5
Burner
Atomizing
designation 0.1 0.5 1 5 6 8 12 16
Air,
scfh
6841-7
1860
4 160
5 900
13 100
14 400
16 600
20 400
23 500
1700 at 20 osi
6841-8-B25
6750
11 500
16 500
36 900
40 400
46 700
57 200
66 000
420 at 15 psi
Metric Conversions
1 osi = 43.94 mm H
2
O = 0.004 39 kg/cm
2
1"wc
= 25.40 mm H
2
O
1 psi = 0.0703 kg/cm
2
1Btu/ft
3
= 8.899 kcal/m
3
1"
= 25.40 mm
1 Btu/gal = 0.666 kcal/L
C
=
5⁄9
(F – 32)
1 scfh
= 0.028 26 sm
3
/h = 0.026 86 nm
3
/h
1 lb = 0.4536 kg
1gph
= 0.001 05 L/s
Flame Length, inches
1
4
8
12
16
6841-7,
Gas
36 40
50 –
40
6841-7, Oil
27 27
16 –
22
6841-8-B25, Gas
24 30
36-48
36-48
48
6841-8-B25, Oil
24 36
36 36-48
48
Flame dia., inches
6841-7,
Gas
24 30
48 –
24
6841-7, Oil
18 18
14 –
15
Max % Excess Air
0.1
1
4
8
12
16
6841-7,
Gas
–
250 500 400 375 350
6841-7,
Oil
–
150 300 450 500 575
6841-8-B25,
Gas
160
700 120 90 100 160
6841-8-B25, Oil
140 550 1030 1050 1300 1500
main air pressure drop across burner, osi
main air pressure drop across burner, osi
main air pressure drop across burner, osi
12 osi main air pressure drop across burner
16 osi main air pressure drop acrosss burner
Flame Length
Without atomizing air.
With 150 scfh atomizing air at 1 psi.
Excess Air
Main and Atomizing Air Capacities in scfh
ENERG
Y | C
OMBUSITION
