Product Overview | Dual-Fuel ™ Burners
HIGH VELOCITY TILES 6425- -MB Burners have a 13 ½ " "Milk Bottle" tile with reduced outlet; they produce higher velocity flames than the standard burner, also offer somewhat better protection for burner internals from furnace radiation. Good tile installation practice is important with any burner (see Supplements DF-M1 and -M2). It is critical with Milk Bottle tiles because of higher pressures developed in the tile, which can cause burner and furnace wall damage if not properly sealed. into the wall. 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. All burners should use flame supervision if they operate in combustion chambers that are below 1400°F during at least part of their cycles. Interrupted pilots are required for such installations. For continuous high temperature furnaces and those with 1400°F flame supervision bypass systems, intermittent pilots are sometimes used: These should be turned off in all applications above 2000°F to avoid overheating burner body and mounting.
CONSTRUCTION Metal parts are shielded by refractory: the tile and an insulating refractory "biscuit" covering face of burner. Mounting plate and burner body are made of heat resistant cast iron. Burner tile is 3200°F castable material. Air tubes are high grade alloy. The standard burner is limited to operation with gaseous fuels and distillate oils. The standard materials of construction are not suitable for operation with heavy oils. 6425 Burners are designed specifically for higher temperature operations such as forge furnaces, ceramic kilns, metal and glass melters, heat treat furnaces, etc. They are the high temperature version of North American's 6422 Fire.All Burner, one of the most widely used industrial burners in the world. 6425's are particularly appropriate for applications that run at both high and low temperatures--an example is a batch type kiln in which early parts of the cycle run below 1200°F and require free oxygen in kiln atmosphere for raw material to process prop- erly; then frequently the product must "soak" at temperatures above 2000°F. 6425 Burners handle this duty with ease due to their excess air flexibility and their construction that withstands radiant heat.
In furnace chambers above 2000°F, combustion air should not be turned down below 2 osi (with or without fuel on).
Table II. MAXIMUM EXCESS AIR RATES in % (with 9 long tiles, without pilot)
Table I. TOTAL AIR CAPACITIES * scfh (for Btu/hr, multiply by 100)
GAS
OIL
Combustion Air pressure
Combustion Air pressure
Burner designation
Burner designation
16 osi air at burner
1 osi
8 osi 14 osi
1 osi 8 osi 14 osi
6425-2 6425-3 6425-4 6425-5 6425-6
2 600 4 100 6 300 10 300 15 700 27 000 33 500 44 800
6425-2 6425-3 6425-4 6425-5 6425-6
— 380
500
—
380 480 800 250 560 330 700 280
500 670 900 400 610 450 830 350
330 560
1000 1560 1440 1000 4900 1450
1300 1560 1150 1400 1000 1600
210
480
1070
50
380
140 160 150 200
6425-7-A 6425-7-B 6425-8-A
6425-7-A 6425-7-B 6425-8-A
3200
900 460
660
400
NOTE: Excess air ratings are based on operation in a cold open furnace. 14-16 osi atomizing air. It may be necessary to reduce atomizing air pressure to obtain maximum excess air.
* Includes combustion and atomizing air.
Table III. MAIN AIR CAPACITIES scfh (not including atomizing air)
Table IV. ATOMIZING AIR CAPACITIES scfh
Burner
air pressure drop across the burner in osi
Burner
air pressure across burner, osi
designation
0.1
1
5
8
12
16
designation
14
16
18
20
6425-2 6425-3 6425-4 6425-5 6425-6
160 280 460 750
520 890
1 160 1 980 3 240 5 300
1 470 2 500 4 100 6 700
1 800 3 050 5 000 8 150
2 100 3 550 5 800 9 450
6425-2, -3, -4
500 640 800 870
520 690 850 930
560 720 910
600 760 950
6425-5 6425-6
1 450 2 370 3 700
6425-7-A,-7-B
990 1040 3000 3170
1180 2070 2580
8 300 10 500 12 900 14 800
6425-8-A
2650
2840
6425-7-A 6425-7-B 6425-8-A
6 550 14 600 18 500 22 700 26 200
8 150
18 200 23 000 28 200 32 600
3320 10 500 23 500 29 700 36 400 42 000
Bulletin 6425 Page 2
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