Specifications

Equipment Description
676-110306 1-5
1.3.3 Entrance Baffle and Exhaust Stack
The entrance baffle isolates the heating section from the ambient air outside the furnace entrance. It is housed in
a welded stainless steel shell lined with ceramic fiber insulation. An N
2
or CDA gas curtain and a series of
hanging stainless steel baffle plates serve to act as a thermal barrier as well as purge the baffle and block ambient
air from entering the furnace.
A venturi-assisted exhaust stack, known as an “eductor”, draws furnace gases across a removable drip tray to
prevent exhaust condensation from falling into the baffle section and contaminating the product.
1.3.4 Heating Chamber
The furnace chamber is similar in construction to the entrance baffle and may be hermetically sealed with
plenum box covers over the lamp ends. Inside this section, arrays of tungsten filament quartz heating lamp tubes
located above and below the belt, generate intense near-wave (sometimes called “short-wave”) infrared light
with a color temperature of 2500 K (peak wave length of 1.16 µm). These lamps are very efficient heaters with
very fast response times, producing up to 600W per lamp at full power and capable of heating the furnace
chamber to a state of equilibrium within minutes.
Lamp Arrangement. The lamps are arranged symmetrically above and below the belt. The top and bottom
lamps may be used independently or together to provide the best possible heating configuration for any
particular process. Table 1-1 Furnace Arrangement shows the distribution of lamps and available power in
each zone.
Table 1-1 Furnace Arrangement
Zone Length (mm)
# of Lamps
Top / Btm
Lamp
Spacing (mm)
Standard Furnace
Max. Available
Zone Power (W)
High Power Furnace
Max. Available
Zone Power (W)
1 190 4 / 4 30 4800 4800
2 380 6 / 6 58 3800 – 4800* 7200
3 190 4 / 4 30 4800 4800
*Depends on power line voltage; 208 Vac: 3800W; 220 Vac: 4200W; 230 Vac: 4500W; 240 Vac: 4800W
Standard and High Power Configurations. LA-306 furnaces are wired in standard configuration or high
power configuration. In the standard configuration Zones 1 and 3 are wired with two (2) parallel strings, each
consisting of two (2) lamps in series. Zone 2 is wired with two (2) parallel strings, each string consisting of three
(3) lamps in series. High power models differ only in Zone 2 which is wired with three (3) parallel strings, each
string consisting of two (2) lamps in series. Lamps within the furnace are arranged as follows: Either model will
perform well throughout the design temperature range of the furnace (100-1000⁰C ), the standard model is
optimized for 100-500⁰C operation, while the high power model is optimized for 500-1000⁰C operation. Each
configuration is summarized in Table 1-2.
Table 1-2 Furnace Lamps Wiring Configuration
Standard Configuration High Power Configuration
Zone
Strings
Top/Btm
Lamps per String
Top/Btm
Strings
Top/Btm
Lamps per String
Top/Btm
1 2 2 2 2
2 2 3 3 2
3 2 2 2 2
Chamber Process Gas. Process gas (CDA, N
2
, FG or other gas) is preheated before reaching the furnace
interior by allowing it to permeate through the hot porous ceramic fiber insulation. This method of gas
distribution does not affect the temperature profile and helps keep the furnace interior clean.