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 

= 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 

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 

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

Catalog Combustion 2021 - Page 0825

Fives Group
FIVES GROUP
FIVES GROUP-FIVES GROUP-0825-0829

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