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EVEN ELEMENT PLACEMENT AND ZONE CONTROL FOR HIGH UNIFORMITY
The elements are normally divided into top and bottom zones. The control output is routed through two input switches, which allow adjustment of the total time on to each zone. If SCR power controls are used these can be zoned using digital biasing switches. Coiled alloy elements are evenly spaced along the sides, back, and door creating an even wall of radiation. The standard furnace is uniform to within +/-25F ( +/-15C) or better at 1500F (815C). Optional fan systems and multiple control zones are available for uniformity of up to +/-10F (+/-5C).
CERAMIC ELEMENT HOLDERS
The elements are supported in proprietary ceramic element holders. These provide perfect support for the coiled elements as well as excellent radiating characteristics. The smooth surface prevents premature failure of the element as it expands and contracts. The holders are kept in place on the insulation walls with specially designed ceramic clamps and screws which fasten to a stainless steel mesh screen, which is an integral component of the insulation module.
LOW DENSITY CERAMIC FIBER INSULATION
The furnace, except for the car, is insulated with low density, high “K” factor ceramic fiber and mineral wool for fast heat up and cool down. The total insulation thickness is 8”. 2600F(1425C) fiber is used for 2200F (1200C) furnaces and 2300F (1260C) fiber is used for 2000F (1095C) or below. No asbestos is used.
HEAVY DUTY CASE
The case is made of strongly reinforced 3/16” thick steel with an integrated base fabricated of heavy square tube and angle sections. Case is entirely primed with 800F silicone paint and finished in machine enamel.
CAR BOTTOM FEATURES ELECTRIC DRIVE
The car bottom is made with heavy plate steel and structural members. The perimeter of the car is cast with a reinforced and anchored castable that is suitable for heat shock. Inside this perimeter, the car is insulated with insulating firebrick and surfaced with 2” cast slabs of castable for heavy duty wear resistance. Alternately, cast piers for easy forklift loading can be provided. Low mass cars are also available depending on the load configuration and weight. The car is driven in and out of the furnace with a car mounted AC brake motor drive. A cable reel feeds power to the car. Railroad type rails are provided with mounting plates. These can be mounted in or on the floor. Flanged wheels on car match rails.
TIGHT, TROUBLE FREE PNEUMATIC CAR SEALS
The car seals feature a wide pad of ceramic fiber blanket. These are pushed by pneumatic cylinders against the castable edge of the car. They retract when the car is about to be moved. Limit switches prevent car movement unless the seals are fully retracted. This seal is extremely tight and features low wear because there is no rubbing.
DOOR AND SEAL
The door seal is also a wide pad of ceramic fiber, which seals against a rigid ceramic fiber board attached to the case front. The most common door is an electrically operated counterbalanced vertical door with a torque limiter to guard against jams. Seal is by adjustment of gravity using the counterbalance. Car mounted doors and double pivoted horizontal doors are available.
DIGITAL PID CONTROL AND HIGH LIMIT SYSTEM
The standard control is a Honeywell UDC 2000 digital PID 3 mode tuning control. All fuses, transformers, contactors, and controls are housed in a NEMA 12 panel with a panel mounted fused disconnect switch. Quiet, long life mercury contactors are standard , although SCR power control is a common option. Thermocouples are inconel sheathed Type K. Thermocouple break protection is included. A Honeywell UDC 2000 digital high limit back up control with manual reset, back up contactors and separate thermocouple is provided. Limit switch shuts off element power if the door is opened. Lighted NEMA 13 On/Off switch included. Control voltage is transformed to 120 volts. The control circuit and each power branch circuit are fully fused. Single point power connection. Meets National Electrical Code.
TESTING AND INSTRUCTIONS
The furnace is power tested to insure proper watt ratings. A complete instruction manual includes easy start up instructions, theory of operation, maintenance instructions, parts list, general dimension drawing, general assembly and subassembly drawings where required, and a detailed trouble shooting guide. A ladder logic diagram and panel layout are prepared on CAD for easy readability.
WARRANTY
The furnace is warranted for one year except for elements and thermocouples (warranted for 6 months.)
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