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Box Furnaces

Recirculating box furnace

BULLETIN
FH-750

2000°F
HEAVY DUTY
ELECTRIC AND GAS
HEAT TREATING
FURNACES


 

Grieve standard 2000°F Heat Treating 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. Twelve standard models from 3.9 to 96 cubic feet, built for long, hard, continuous use.

STANDARD FEATURES Back to Top
UL LISTED CONTROL PANEL

Standard Box Furnaces from Grieve meet the requirements of National Fire Protection Association Standard 86, Industrial Risk Insurers, Factory Mutual and OSHA standards. For some applications, such as those involving special atmospheres or hazardous locations, the above organizations require additional safety devices.

Controls
—Digital, microprocessor based, thermocouple actuated, indicating temperature
   controller
—Modulating burner on gas furnaces
—Motor control push buttons and on-off heat switch
—LED pilot lights


Safety Equipment — Electric Furnace
—Adjustable, thermocouple actuated, manual reset excess temperature interlock
—Separate heating element control contactors
Door interlock switch turns off power to heating elements when door is opened;
   restores power when door is closed


Safety
Equipment — Gas Furnace
—Adjustable, thermocouple actuated, manual reset excess temperature interlock
—Electronic flame safeguard protection
—Exhauster air flow safety switch
—Recirculating blower air flow safety switch
—Purge timer
—High and low gas pressure switches
—Two pilot safety shutoff valves with leak test stations
—Two main safety shutoff valves with leak test stations (Industrial Risks Insurers
   vent valve only provided on specific request)
—Valve position indicator on main safety shutoff valves
—Over 400,000 BTU/HR safety shutoff valve interlocked with purge timer

Construction
—3/16" steel plate reinforced furnace shell
—1/2" thick steel front plate
—Brushed stainless steel control panel face
—Powered vertical lift door
—Door hot side faces away from operator at all times
—Energy-saving lightweight ceramic fiber insulation reduces operating costs
—Heavy duty ceramic hearth plates supported by firebrick piers
—Excellent temperature uniformity throughout work space
—Fast heat-up and cool-down
—1 year limited warranty


All equipment fully assembled and individually factory tested

 

   
SPECIFICATIONS Back to Top
NOT FOR USE WITH FLAMMABLE SOLVENTS, VAPORS OR GASES
Model
Work Space
Outside
Dimensions*
(WxDxH)
Height
Door
Open
Door
Type
Hearth
Rating
Lbs‡
Heat Input
Operating Characteristics†
Approx
Shipping
Weight
Dimensions
(WxDxH)
Volume
Cu Ft
KW
BTU/HR
Control
Accuracy
Furnace
Uniformity
Rise Time
230V 460V
HD-153015 15" x 30" x 15" 3.9 37" x 53" x 63" 78" Manual¹ 230 18** 225,000 ± 0.3% ±15°F 45 min 35 min 1500 lbs
HD-183618 18" x 36" x 18" 6.7 55" x 79" x 74" 100" Electric 320 24 300,000 ± 0.3% ±15°F 175 min 130 min 2650 lbs
HD-243618 24" x 36" x 18" 9 61" x 78" x 77" 100" Electric 450 33 360,000 ± 0.3% ±15°F 135 min 120 min 3000 lbs
HD-243624 24" x 36" x 24" 12 61" x 78" x 80" 112" Electric 450 40 440,000 ± 0.3% ±15°F 125 min 110 min 3600 lbs
HD-244824 24" x 48" x 24" 16 61" x 92" x 80" 118" Electric 600 48 525,000 ± 0.3% ±15°F 120 min 105 min 4100 lbs
HD-304830 30" x 48" x 30" 25 67" x 92" x 86" 118" Electric 750 56 650,000 ± 0.3% ±16°F 120 min 90 min 4500 lbs
HD-306030 30" x 60" x 30" 31 67" x 104" x 86" 118" Electric 850 60 700,000 ± 0.3% ±16°F 135 min 105 min 5100 lbs
HD-364836 36" x 48" x 36" 36 73" x 92" x 93" 133" Air 950 66 750,000 ± 0.3% ±18°F 140 min 100 min 5250 lbs
HD-366036 36" x 60" x 36" 45 73" x 104" x 93" 133" Air 1150 73 800,000 ± 0.3% ±18°F 140 min 100 min 5700 lbs
HD-367236 36" x 72" x 36" 54 73" x 116" x 93" 133" Air 1350 86 950,000 ± 0.3% ±18°F 140 min 95 min 6300 lbs
HD-484836 48" x 48" x 36" 48 85" x 92" x 93" 133" Air 1200 78 850,000 ± 0.3% ±20°F 135 min 90 min 6200 lbs
HD-484848 48" x 48" x 48" 64 85" x 92" x 105" 157" Air 1400 92 1,000,000 ± 0.3% ±20°F 130 min 90 min 6900 lbs
HD-487248 48" x 72" x 48" 96 85" x 116" x 105" 157" Air 2000 135 1,400,000 ± 0.3% ±22°F 120 min 90 min 8500 lbs
*All Models —Control panel overhang 9" right side.
Gas Models —Combustion blower overhang 36" rear.
   ¹Gas spring assists operation. Construction similar to electric door.
   Heating elements located on sidewalls and roof only; 13.5 KW
   **80 minute Rise Time on 230 volts.
†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 furnace. Performance will vary with load and application. See Bulletin TC-920 for additional details.
‡Uniformly distributed.
STANDARD EQUIPMENT   Back to Top
All Models
— 208 volts, 3-phase, 60 Hz
— 230 volts, 3-phase, 60 Hz
— 460 volts, 3-phase, 60 Hz
— Other electrical characteristics available

Wall insulation, 9" thick, consisting of:
— 5" of 2300°F, 8 lbs/cf ceramic fiber blanket
— 4" of of 1900°'F, 18-1/2 lbs/cf block insulation


Floor insulation, 8-1/2" thick, consisting of:
— 4-1/2" of 2300°F insulating firebrick
— 4" of 1900°'F, 18-1/2 lbs/cf block insulation


Furnace shell is made of 3/16" thick steel plate reinforced with structural steel. Doorsill constructed from firebrick to protect furnace during loading. Ceramic hearth plates are 2" thick and supported by firebrick piers. Soft insulation on door provides an excellent heat seal by pressing against the vestibule refractory and the 1/2" thick steel front plate. Exterior painted with Trilite Green enamel.

Each features completely wired, side access UL listed control panel assembled on the furnace enclosing terminals for incoming power, temperature controllers, push buttons and pilot lights.

Electric Models
Safety devices as listed at the top of this bulletin. Heating element contactors electrically interlocked with door to shut off power to heaters as door opens and restore power when closed. High temperature alloy wire heating elements supported in vacuum cast ceramic fiber. Heating elements located at sides, rear, door, and under hearth, except as noted.

Gas Models
— 1,000 BTU natural gas at 2 psig pressure;
    1" NPT inlet up to 800,000 BTU/HR;
    1-1/4" NPT 850,000 to 1,000,000 BTU/HR;
    1-1/2" NPT at 1,400,000 BTU/HEATER
— Other gas characteristics available

Safety devices as listed at the top of this bulletin. Automatic pre-ignition purge period and push button electric ignition contributes to ease of operation. Modulating gas burners fire beneath hearth from opposing sides to circulate heated air through the work space (HD-153015 has single burner firing above load from rear). Gas burners protected with electronic flame safety relay. Door interlock switch drives main burner to low fire when door is opened and restores control when door is closed.
 
ELECTRIC DOOR
Door pivots upward above furnace, clearing front for easy loading. In the closed position, full door weight seats door firmly against furnace face. Structural steel pivot arms are supported at furnace sidewalls by bearings and connected to a heavy duty electromechanical actuator. The door is controlled by a switch at the furnace control panel.


AIR DOOR
Door rises vertically in front of the furnace hanging from heavy duty roller chain, sprockets, shaft and pillow block bearings. In the closed position, rollers at the sides of the door engage support brackets to force the full door weight against the furnace face. Large diameter air cylinder rotates support shaft to lift the door. The door is controlled by a manual air valve with supply filter, lubricator and regulator.
.


 
ADDITIONAL EQUIPMENT AVAILABLE Back to Top

See Bulletin TC-960 for modifications and other optional equipment.

Programmable Temperature Controller, microprocessor based, digital indicating, thermocouple actuated, in lieu of standard controller
Option PTC3


Recording Thermometer, thermocouple actuated, 24-hour, 10" diameter circular chart, used in conjunction with standard controller, includes floor stand to house recorder. Floor stand cannot be used for storage
Option RT


Digital Timing Temperature Controller,
microprocessor based, digital indicating, incorperates 99 hour 59 minute timer. Starts timing when temperature reaches set point and shuts down oven at end of set time
Option DTS3

 


Digital Shut Down Timer, with continuous "hold" feature
Option SDT


Digital Batch Timer, for uniformly timing batch operations. Continuous alarm with door interlock; alarm at end of preset time period until door is opened or timer reset
Option BT


Alloy Hearth Tray, made of heat resisting high temperature alloy, for protecting ceramic hearth plates from impact and heavy loading
Option AH


Recirculating Fan, water cooled fans standard, air cooled available, improves temperature uniformity from 600F to 1600F, available on Model HD-304830 and larger, may reduce heat input on electric models, not available on gas models
Option RF


Inert Atmosphere Construction, electric only, includes continuously welded shell, inert atmosphere gas inlet and outlet, sealed terminal boxes, recirculating blower shaft seal, high temperature door gasket, optional forced cooling systems are available at additional cost
Option IAC


Inert Atmosphere Inlet Piping, with indicating flow control and manual gas valve. Specify atmosphere
Option IAIP

 
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