Heavy Duty Box Furnace

These  furnaces are used for a variety of heat treating applications such as tempering, hardening, sintering or firing, including those requiring inert atmospheres. 

Precision microprocessor based temperature controls and energy-saving insulation maximize the performance of these rugged units.

Outside Dimensions

• All Models: Control panel overhang 9″ right side
• Gas Models
• Combustion blower overhang 36″ rear
• Gas spring assists operation. Construction similar to electric door
• Heating elements located on sidewalls and roof only; 13.5 KW

Operating Characteristics

• Accuracy as percent of controller span
• Uniformity at 100°F below maximum temperature
• Rise Time in minutes to 100°F below maximum temperature
• Tests run with empty oven and minimum exhaust
• Performance will vary with load and application

Certifications

• UL Listed Control Panel
• Meets the Requirements of the Following Standards:
• NFPA 86 (Standard for Ovens and Furnaces)
• NFPA 70 (National Electric Code)
• FM (Factory Mutual)
• OSHA

Caution

• When processing combustible material fire protection should be considered
• Not for use with flammable solvents or vapors. Other models available for these applications

Safety Equipment

• Adjustable manual reset excess temperature interlock to turn off heat on malfunction of main temperature controller

Electric Heat Includes

• Separate heating element control contactors to turn off heat on malfunction of main control contactors
• Door interlock turns off power to heating elements when door is opened to protect operator from line voltage at heating elements

Gas Heat Includes

• Multiple modulating burners fired under hearth from opposing sides to circulate heated air (single burner at top of work space on HD-153015)
• Automatic pre-ignition purge period to clear accumulated gas or fumes from furnace
• Push button electric ignition
• Microprocessor based electronic flame safeguard protection for each burner to continuously monitor flame and close gas valves if flame is not present
• Combustion air blower
• Combustion Blower air flow safety switch to close gas valves on loss of combustion air flow
• High and Low gas pressure switches to confirm safe operating pressure range
• Two pilot valves for each pilot to guarantee gas flow to pilot can be stopped
• Two main safety shut off valves for each burner with valve seat position indicator to assure gas flow to each main burner can be stopped
• Proof of closure switch on one main valve at each burner to prevent igniting pilot unless main valve is closed
• Leak test station at each pilot and main burner valve to allow testing for leakage through valve
• Door interlock drives main burners to low fire as door is opened to protect operator from flames

Construction

Choice of

* Air or Inert Atmosphere construction

* Electric or Gas heat (Air construction only)

* 208 volt, 230 volt or 460 volt, 3-phase, 60 HZ – other input power available

• All welded construction
• High temperature Kanthal A-1 coiled wire heating elements supported in vacuum cast refractory ceramic fiber located on all walls and beneath hearth
• 1000 BTU per cubic foot natural gas at 2 psig pressure – propane available. Inlet 1” NPT up to 800,000 BTU/hr, 1-¼ “ NPT to 1,000,000 BTU/hr, 1-½” NPT above 1,000,000 BTU/hr
• Insulated with 9”of light weight, energy saving refractory ceramic fiber
• Load supporting floor insulated with 4” of 18-½ lbs per cubic foot density 1900⁰F block and 4-½” of firebrick,
• 3/16” steel plate reinforced furnace shell with Trilite Green enamel finish
• ½” thick steel front plate around door
• Fire brick throat and doorsill to protect furnace during loading
• Brushed stainless steel control panel face
• Powered vertical lift door (gas spring assisted manual door on HD-153015)
• o Electric door: Electromechanical operator pivots door, supported by structural steel arms and bearings, upward above furnace
• o Air door: Air cylinder lifts door hanging from heavy duty roller chain supported by sprockets, shaft and pillow block bearings
• Door hot side faces away from operator
• Soft insulation on door hot face seals against throat brick and steel front plate
• 2” thick , heavy duty ceramic hearth plates supported by fire brick piers
• Fully assembled and factory tested

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Standard & custom-made Grieve ovens in action