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A WIDE VARIETY OF HEARTHSThe standard hearth is one or more ceramicplates elevated on ceramic blocks 1-1/2”above the bottom elements. This air spaceimproves uniformity. Silicon carbide plates,alloy plates, roller hearths, baskets, racks,loaders, castable piers, air cooling tables andmany other loading options are available.CERAMIC ELEMENT HOLDERSThe elements are supported in proprietaryhigh temperature ceramic element holders.These provide perfect support for the coiledelement and excellentradiatingcharacteristics.The smooth surfaceof the holderprevents prematurefailure of theelement as it expandsand contracts.Theseholders,coupled witha unique all ceramicelement terminal, make elementreplacement easy. Being recessed into thewall of the furnace these elements are not assusceptible to mechanical damage as someother types of element support systems.CERAMIC ELEMENT TERMINALS MAKEELEMENT CONNECTIONS EASY ANDTROUBLE FREEUnique all ceramic element terminal blocksdesigned by L&L allow the element ends to beclamped without twisting the whole endaround a terminal bolt, making it easy toremove an element. The connection wires canbe easily removedwithout disturbingthe element termination(which allowsyou to easily isolatean element for aresistance check).The heavy ceramicterminal block featuresunusually good electricalisolation andprotects the wires.DOUBLE PIVOTED PLUG DOOR KEEPSHEAT AWAY FROM OPERATOR ANDALLOWS FOR TIGHT DOOR SEALThe standard door is a double pivotedhorizontal plug door. The double pivotingallows the door to open like a parallelogramwhich keeps the hot face away from theoperator. There are two heavy duty clampsfor tight sealing. Because of the completelyhorizontal motion of the door as it is sealingthere is no wear on the seal face. The doorhas a 3/4” refractory plug which protrudesinto the furnace chamber and provides ahighly effective heat lock. There is a 3-1/2”refractory to refractory seal around thePage 8perimeter of the door. Counterbalancedvertical doors with hand crank, pneumatic orelectric actuator are options. Vertical doorslift away from the furnace seal before liftingup. Strong 3/16” thick reinforced door casingprevents door from warping from heat.PRESHAPED BRICK SECTIONS SAVE ONHEAT LOSS AND MAINTENANCE COSTSThe firebrick is cemented in sections on avery flat table. These sections are thenprecision cut and routed. All sections fittogether with engineered heat locks whichimprove the insulating integrity of the furnaceeven after many years of service. Bricksections can easily be installed by in-housemaintenance personnel saving on expensiveand hard-to-find specialized bricklayer labor.All refractory is coated with a special facingthat prolongs firebrick life and helps preventspalling and dusting.EFFICIENT MULTILAYERED INSULATIONThe furnace is insulated with 4-1/2” of low Kfactor refractory firebrick backed up by 2” ofmineral wool board on all surfaces except thebottom, which has 2” of hard calcium silicateback up for solid hearth support. This yieldsan excellent combination of strength, insulatingquality, and fast heat up and cool downtimes. The roof of all models which are 24”wide or wider is made from 2600°F (1425°C)ceramic fiber modules to prevent roof failure.SIDE MOUNTED CONTROL PANEL WITHHINGED DOOR HOLDS ALL COMPONENTSAll temperature controls, relays, contactors,power controls, switches, transformers andfuses are located in a side mounted NEMA 1control panel with a gasketed hinged door.An oil tight NEMA 13 lighted on/off pushbuttonswitch turns the furnace on. Controlsare mounted at eye level for easy visibility. ANEMA 12 panel with fused disconnect switchis optional. A panel cooling fan is includedwith SCR power controls.DIGITAL HONEYWELL UDC2300 PIDTEMPERATURE CONTROLA Honeywell UDC2300 microprocessorbased digital single set point control isstandard. Two full vacuum fluorescentdisplays include English language programminginformation for easy set up. This is one of theeasiest digital controls to operate. Accuracyis .25% of scale. All PID tuning constants(proportioning band, reset, rate) plusmaximum temperature, scale range, thermocoupletype and many other parameters areprogrammable. Ramp/Soak programming isoptional. Multi-zone UMC800 controls arealso used. Other controls are optional.DIGITAL HIGH LIMIT CONTROLA Honeywell UDC2300 digital high limitcontrol, complete with back up contactorsand separate thermocouple, shuts off furnaceif temperature or power control fail.MERCURY CONTACTORS FEATURE FASTCYCLE TIME FOR ACCURATE CONTROLOther benefits are long contactor life and quietoperation. SCR power controls are optional.TYPE K THERMOCOUPLES WITHSHIELDED EXTENSION WIREType S platinum thermocouples are optional.MANY SAFETY FEATURESThermocouple break protection is included.Limit switches shut off power to furnace ifthe door is opened or the power panel backis removed. Control voltage is transformedto 120 volts. The control and branch powercircuits are fully fused.This is a very typical XLE 246 with cast piers and a standard double pivoted horizontal door.www.hotfurnace.com