Tempering Furnaces

BULLETIN
TF-740

1400°F
FORCED CONVECTION
HEAVY DUTY
ELECTRIC AND GAS
TEMPERING FURNACES

 

Grieve standard 1400°F Tempering Furnaces are used for a variety of heat treating applications including those requiring inert atmospheres. Recirculating blower provides high velocity vertical down air flow for excellent heat transfer from 800°F to 1400°F. Precision microprocessor based temperature controls and energy-saving insulation maximize the performance of these rugged units.

STANDARD FEATURES Back to Top
• UL LISTED CONTROL PANEL

• Standard Tempering furnace ovens 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 controller
—Separate heating element control contactors
—Recirculating blower air flow safety switch

 • Safety Equipment — Gas Furnace
—Adjustable, thermocouple actuated, manual reset excess temperature controller
—Electronic flame safeguard protection
—Stainless steel powered forced exhauster
—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
—Vertical down air flow specifically designed for tempering
—High pressure, air cooled, stainless steel recirculating blower
—Adjustable patented opposed louvers on full coverage supply and return ductwork
—3/16" steel plate reinforced furnace shell
—1/2" thick steel front plate
—16 gauge stainless steel interior
—Work space bottom reinforced with stainless steel grid
—Brushed stainless steel control panel face
—Powered vertical lift door; hot side faces away from operator
—Energy-saving lightweight ceramic fiber insulation
—Fast heat-up and cool-down
—Built-in baffles prevent radiant heat
—Adjustable fresh air intake and exhaust dampers
—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
Blower
Door
Type
Hearth
Rating
Lbs‡
Heat Input
Operating Characteristics†
Approx
Shipping
Weight
Dimensions
(WxDxH)
Volume
Cu Ft
CFM
HP
KW
BTU/HR
Control
Accuracy
Furnace
Uniformity
Rise Time
230V 460V
TF-183618 18" x 36" x 18" 6.7 35" x 87" x 74" 78" 2400 3 Electric 400 30 190,000 ± 0.3% ±12°F 95 min 85 min 3100 lbs
TF-243624 24" x 36" x 24" 12 47" x 92" x 80" 90" 3500 5 Electric 600 42 285,000 ± 0.3% ±14°F 95 min 85 min 4000 lbs
TF-304830 30" x 48" x 30" 25 53" x 106" x 86" 102" 4250 5 Electric 900 52 355,000 ± 0.3% ±14°F 90 min 80 min 5200 lbs
TF-364836 36" x 48" x 36" 36 59" x 111" x 126" 126" 5300 5 Air 1100 65 450,000 ± 0.3% ±20°F 90 min 80 min 6400 lbs
TF-366036 36" x 60" x 36" 45 59" x 121" x 126" 126" 6000 7-1/2 Air 1300 74 510,000 ± 0.3% ±20°F 90 min 80 min 6800 lbs
TF-484848 48" x 48" x 48" 64 71" x 114" x 150" 150" 8000 10 Air 1500 100 660,000 ± 0.3% ±22°F 80 min 70 min 8700 lbs
TF-487248 48" x 72" x 48" 96 71" x 152" x 150" 150" 9600 15 Air 2200 120 800,000 ± 0.3% ±22°F 80 min 70 min 9950 lbs
*All Models —Control panel overhang 9" right side.
   Blower motor overhang 18" rear except 20" on 15 HP.
Gas Models —Burner overhang 18" right side.
   325 CFM exhauster to 510,000 BTU/HR, 650 CFM above.
†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, 7" thick, consisting of:
— 1" of 2300°F, 8 lbs/cf ceramic fiber blanket
— 2" of 1700°F, 4 lbs/cf ceramic fiber blanket
— 2" of 1900°F, 15 lbs/cf block insulation
— 2" of 1200°F rockwool insulation

Floor insulation, 6-1/2" thick, consisting of:
— 4-1/2" of 2300°F insulating firebrick
— 2" of 1900°'F, 18-1/2 lbs/cf block insulation

• 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 temperatures alloy coiled wire heating elements supported in alloy rack. Heating elements located in heat chamber upstream of the recirculating blower. Exhaust outlet 4" diameter.

• Gas Models
— 1,000 BTU natural gas at 2 psig pressure; 1" NPT inlet up to 800,000 BTU/HR
— 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 burner fires into chamber upstream of the recirculating blower. Gas burner 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. Exhaust outlet 6" diameter.
  		Furnace shell is made of 3/16" thick steel plate reinforced with structural steel. Doorsill constructed from firebrick to protect furnace during loading. Stainless steel grid at bottom of work space to distribute loading. 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 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.

Circulation Diagram
(Side View)


Full vertical downward air flow provides
excellent heat transfer and uniform
temperature distribution.

 
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

• Programmable Recording Temperature Controller, microprocessor based, thermocouple actuated, digital display, 24-hour, 10" diameter circular chart, in lieu of standard controller
Option PRTC3

 


• 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

• Shut Down Timer, with continuous "hold" feature; 1, 5, 10 or 30 hour range
Option SDT

• 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; 1, 5, 10 or 30 hour range
Option BT
• Automatic Door Switch, turns off blower and heat when door is opened. Restores blower and heat on electric models, blower only on gas models, when door is closed
Option ADS
• 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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