Product Overview | 6821 Magna-Flame ™
FEATURES
CONTROL. The burner operates with main air pressures from 0.2 to 10"w.c. If combustion air temperature varies during normal operation, metered flow control with air temperature compensation is recommended--use North American’s 8196 or 8199 Combustion Controllers. IGNITION and FLAME SUPERVISION. Magna-Flame burners should be pilot ignited . Pilot ignition must occur at 1"w.c. main air pressure or less. Appropriate 4014 gas-boosted pilots are to be used with this burner (sold separately), and are shown on the dimension table. Pilot operation must be interrupted to prevent overheating of the mounting. Self-checking UV scanners (sold separately) are recommended for flame supervision. See Bulletin 8832 for selection of UV adapters. It is possible for a UV scanner mounted on this burner to sight flame(s) of other burners in the same firing chamber. Consult North American for configuration guidance on multiple burner applications. INSTALLATION. The burner does not include a refractory tile. The shape shown on the dimension drawing (page 2) must be built into the combustion chamber wall. See Supplement DF-M1 for installation recommendations. REPLACEMENT and SPARE PARTS. NOTE: In October, 2009, the 6821 burner was redesigned to change from a square mounting flange to round and replace the threaded gas connection with a flanged gas tee. When replacing burners, or ordering parts, please inform your sales professional of the complete part number, sales order and/or manufactured date. This information is stamped on a tag located on the burner back plate.
6821 Hot Air Magna-Flame ™ Burners operate with hot air from recuperators or other heat recovery devices to save energy on furnaces, such as steel reheat, aluminum melting, process heaters, and other high temperature applications. Typical operation is with 1000°F air at a pressure of 10"w.c. CONSTRUCTION. Bodies, featuring round mounting flanges, are fabricated heavy-gauge carbon steel and lined with ceramic fiber and castable refractory. Internal parts are heat-resistant alloy and the stabilizing disc is faced with high alumina refractory. OPERATION. Gas flames are stable in cold, tight combustion chambers even when starting with ambient temperature combustion air. Under these conditions, natural gas flames are semi-luminous. For stoichiometric firing, required natural gas pressure is a minimum 60 percent of the air pressure. Use approximately 4 osi atomizing air for cooling purposes when burning gas. 6821 Burners use 5654 low pressure (cold) air atomizers that require 28 osi air pressure at the atomizer connection. Fuel oil grades #4 and #6 must be heated to reduce viscosity to 100 SSU. Stoichiometric operation requires less than 4 psig oil pressure at the nozzle. For applications using gas or #2 oil that benefit from high velocity, such as aluminum melters and holders, steel reheat furnaces or others, the 6821 is available in an "R-version". The refractory tile port of the R version is reduced (converging) to produce high hot-gas exit velocities, resulting in increased convective heat transfer and at the same time entrainment of surrounding furnace gases resulting in low NOx emissions. The R-version is not recommended for heavy oil (grades #4 and #6). — Fuel gases (500 Btu/ft 3 or higher) — Fuel oils #2 through #6 — Sharp, well-defined flames — Excellent performance with cold or hot air
Bulletin 6821 Page 2
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