MULTILAYERED, EFFICIENT, HIGH ALUMINA CERAMIC FIBER INSULATION
The furnace is insulated with multi-layered high alumina and alumina-silicate ceramic fiber board. The hot face is prefired high alumina board by Zircar or Rath. The insulation is segmented and supported by a series of splines, alumina rods and sapphire clips. This is the most critical part of the furnace design in terms of longevity. Triple heat locks are designed into the system for extra protection at high temperatures. A vestibule protects the molybdenum disilicide elements, and prevents excessive heat loss when the front door is opened. No asbestos is used.
MOLYBDENUM DISILICIDE ELEMENTS
The elements are molybdenum disilicide Super 33 U-shaped elements. These will withstand (3275F) 1800C in air. All electrical connections are at the top, and the elements are suspended from the roof. The electrical resistivity of these elements remains constant over time with little aging. This allows replacement of one element without changing all elements, a distinct advantage over silicon carbide elements. Low watt density is designed into the elements for maximum element life. All aluminum element connection hardware is used to prevent galvanic corrosion.
DOUBLE WALL CASE CONSTRUCTION
The insulation module has its own rigid refractory board exterior. This insulation module is inserted into a ventilated steel casing leaving an air space between the exterior case and the insulation module. This allows for cooling of the insulation, important in long insulation life, and helps maintain a cool external case temperature. Larger furnaces feature integral cooling fans to insure good cold face strength of the insulation. The two smallest sizes are bench mounted while all others are floor mounted. The case is primed with 800F silicone paint and finished in machine enamel.
DEEP PLUG DOOR CONSTRUCTION
The horizontally opening door features a deep plug type seal with triple heat locks. Two pivots, one on the left and one in the center of the door, insure very tight sealing. A vestibule around the door opening further reduces heat loss and helps protect the elements.
TEMPERATURE UNIFORMITY OF +/-10C ( +/-20F)
Uniformity of +/-10C (+/-20F) is normal above 1200C (2200F) within 2/3 of the working dimensions.
ALUMINA HEARTH SUPPORTED FROM COLD FACE
The hearth is a flat alumina plate (or series of plates) supported by a series of insulating alumina posts which transfer the weight of the hearth all the way to the bottom of the cold face of the bottom insulation.
FAST HEAT UP AND COOL DOWN
The all fiber insulation and Kanthal Super 33 elements provide extremely fast heating and cooling response.
PID DIGITAL CONTROL , HIGH LIMIT CONTROL AND SCR POWER CONTROL
The standard control used is a Honeywell UDC 2300 digital PID 3 mode tuning control. All fuses, transformers, contactors, and controls are located in a NEMA 1 panel. A matched transformer and phase angle fired SCR controls power to the elements. This insures even, precise control and long element life. The thermocouples are Type B. The control voltage is 120 volts. A NEMA 13 lighted On/Off switch and NEMA 13 door power cut off switch are included. A Honeywell UDC 2300 digital high limit back up control with manual reset, back up contactors and separate thermocouple is standard. Single point power connection.
TESTING AND INSTRUCTIONS
The furnace is tested to insure circuit integrity. A complete instruction manual includes easy start up instructions, theory of operation, maintenance instructions, parts list, and a detailed trouble shooting guide. A ladder logic diagram and panel layout are prepared on system for easy readability.
The furnace and insulation module are warranted for one year except for elements and thermocouples (warranted for 6 months.)