Bibby Sterilin Lenton EF 11/8 Guide

LF01-1.23
Installation, Operation &
Maintenance Instructions
1100°CChamber Furnaces
EF 11/8&AF11/6
(B models)
This manualis fortheguidance ofoperatorsoftheaboveproducts and should
bereadbefore thefurnace is connectedto theelectricitysupply.
Manuals are supplied separately forthe furnace controller
(and overtemperature controller when fitted).
Pleasereadthecontroller manuals before operating thefurnace.
C
ONTENTS
Section page
1.0Introduction 2
2.0Installation 3
3.0Operation 5
4.0Maintenance 6
5.0Repairs&Replacements 8
6.0Fault Analysis 11
7.0Circuit Diagram12
8.0Fuses&Power Control 13
9.0Specifications 16

EF,AF
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1.0 INTRODUCTION
1.1 Models Coveredby this Manual
This manualcovers currentmodels EFand AF. Pleasenotethatchanges were madeto therange
fromlate2001;thesechanges affectboth thecaseand theinternaldesign. Models madeafter the
changeare suffixed with theletter Bon theratinglabel. Ifa manualfor theearlier design is
required, pleasecontactLenton.
ModelEF11/8Bmaybesetto operateon anyvoltagein therange200-240V(or100-120Vto
order) bycorrectsettingofthepower limit parameter in thecontroller. FormodelAF11/6Bthe
equivalentrangeis 220-240V.
Becauseofthemodelchanges it is veryimportantwhen orderingspares to statethefurnace serial
number orotherwiseto identifythemodelcorrectly.
1.2 Switches and Lights
1.3 Warning Symbols
SupplyLight: when thefurnace is connected to theelectricalsupplythe
lightin theadjacentswitch glows
HeatLight: theadjacentlightglows orflashes to indicatethatpower is
beingsupplied to theelements
DANGERofelectricalshock
–
read anywarningprinted bythis symbol
.
DANGER
–
hotsurface. Read anywarningprinted bythis symbol.
WARNING:all surfaces ofafurnace maybehot.
DANGER
–
read anywarningprinted bythis symbol.

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2.0 INSTALLATION
2.1 Unpacking &Handling
When unpackingorhandlingthefurnace always liftit byits base. Never liftit bythedoor. Use
two peopleto unpack and carrythefurnace.
Removeanypackingmaterialfromthedoorgear and furnace chamber before use.
2.2 Siting &Setting Up
Place thefurnace in awell ventilated room, awayfromother sources ofheat, and on asurface
which is resistantto accidentalspillageofhotmaterials. Do notmountthefurnace on an
inflammablesurface.
Ensure thatthere is free space around thefurnace. Do notobstructanyofthevents in thecase:
theyare needed to keep thecontrols and thecaseexteriorcool.
Ensure thatthefurnace is placed in such awaythatit can bequicklyswitched off ordisconnected
fromtheelectricalsupply-see below.
Ifthefurnace is to beused to heatsubstances which emit fumes, then afumeextraction ductof
about150mm inletdiameter maybeplaced directlyabovethechimneyoutlet. Do notmakea
sealed connection to thefurnace chimneyas this causes excessiveairflowthrough thechamber and
results in poortemperature uniformity.

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2.3 ElectricalConnections
Connection bya qualified electrician is recommended.
Thefurnace requires asingle-phaseA.C. supplywith earth (ground), which maybeLiveto Neutral
non-reversible(polarised), Liveto Neutralreversible(non-polarised), orLiveto Live.
Check thefollowingbefore connection, byreference to thefurnace ratinglabel.
Voltage:thevoltageon thelabeland theactualsupplyvoltageshould becompatible– ifin doubt
contactLenton. See section 2.4
Amps:theactualsupplymustbecapableofsupplyingtherequired amps. Itshould befused atthe
nextavailablefusesizeequalto orgreater than theamps on theratinglabel.
Asupplycableis normallyfitted. In there is no cable, removetheback paneland connecta
suitablyrated cableto theinternalterminals.
Either wire thesupplycabledirectlyto an isolatororfit it with alineplug. Theplugorisolator
should bewithin easyreach oftheoperatorto permit quick disconnection ofthepower.
ForoperatorsafetythesupplyMUST incorporatean earth (ground).
CONNECTION DETAILS supply type
SupplyTerminallabel Cable colour Live-Neutral Reversible orLive-Live
1-phase LBrownTo liveto eitherpowerconductor
NBlue To neutralto the otherpowerconductor
PEGreen/YellowTo earth (ground)to earth (ground)
2.4 VoltageLevel&Power Adjustment
Check thefurnace ratinglabelvoltage. Iftheactualsupplyis notthesameas thevoltageon the
label, then thecontroller power limit should beadjusted.
To alter thepower limit
Iftheactualsupplyvoltageis higher than thevoltageon therating labelor thevoltagefor which
thefurnace was lastset, then do thefollowing operations quicklyand immediatelyafter switch-on.
(Alternatively, temporarilyreduce thetemperaturesetpointto zero to preventheating.)
Press Page /until oP (outputlist)is displayed. Press Scroll Quntil OP.Hi (OutputHigh)is
displayed. Press Down qorUp ponce to displaythevalueof OP.Hi (it is good practice to write
down theoriginalvalue).
To alter theparameter to thedesired valueuseDown qorUp p.
Caution: Do notincreasethepower limit valueto avalueabovethecorrectlevelforthesupply
voltage. Theheatingelements could burn out, orafusecould blow.
Notethatsettingthepower limit to zero prevents thefurnace fromheating.

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3.0 OPERATION
Theinstructions for operating thetemperaturecontroller aregiven in a separatemanual.
Ifthefurnace is fitted with a timeswitch, see also thesupplementarymanualprovided.
3.1 Operating Cycle
Thefurnace is fitted with acombined Supplylightand Instrumentswitch. Thelightis on
whenever thefurnace is connected to thesupply. Theswitch cuts off power to thecontroller.
Connectthefurnace to theelectricalsupply. TheSupplylightshould glow.
Operatetheinstrumentswitch, located on thefrontpanel, to activatethetemperature controller;
the Oposition is off, the Iposition on. Thecontroller becomes illuminated and goes through a
shorttestcycle.
Closethefurnace doorand adjustthetemperature controller – see theseparatemanualsupplied.
Unless atimeswitch is fitted and is off, thefurnace starts to heatup.
As thefurnace heats up theHeatlightglows steadilyatfirstand then flashes as thefurnace
approaches thedesired temperature.
To switch off, settheinstrumentswitch to O. Ifthefurnace is to beleftoff, isolateit fromthe
electricalsupply.
3.2 GeneralOperating Notes
Heatingelementlife is shortened byuseattemperatures closeto maximum. Do notleavethe
furnace athigh temperature when notrequired. Themaximumtemperature is given on thefurnace
ratinglabeland on theback pageofthis manual.
AF: Theelementlife can bereduced byuseofnon-metallichearth plates orother non-conducting
materialcoveringthehearth. Raisethetemperature slowlyover thelast300°C, allowing10
minutes soak at100°Cintervals.
When heatinglargeobjects, in particular poorconductors, avoid shieldingthethermocouplefrom
theheatingelements. Thethermocoupleis intended to sensethetemperature near theheating
element, butifalargecold objectis placed in thechamber it mayrecord theaveragetemperature
oftheobjectand theelement, which can lead to overheatingoftheelement. Allowlargeobjects to
gain heatatalower temperature and then adjustthecontroller setpointto atemperature closeto
thedesired maximum.
When heatingmaterials which produce smokeorfumes, thechimneymustbecorrectlyfitted and
unobstructed. Otherwise, sootmayaccumulatein thechamber and could possiblycausean
electricalbreakdown oftheheatingelement.
Ifthefurnace is used to heatmaterials which emit smokeorfumes, regularlyheatit up to
maximumtemperature foronehourwithoutload to burn awaythesoot.
Materials such as casehardeningcompounds and other reactivesalts maypenetratethefurnace
chamber liningand attack thewire elements, causingpremature failure. Useofahearth tilemaybe
advisable:pleaseconsult ourtechnicaldepartment.
3.3 UseofProbes
Anymetalobjectused to probeinto thefurnace chamber whilethefurnace is
connected to thesupplymustbeearthed (grounded). This applies in particular to
metalsheathed thermocouples, where thesheaths mustbeearthed. Therefractory
materialofthechamber liningbecomes partlyconductingathigh temperatures, and
theelectricpotentialinsidethechamber can beatanyvaluebetween zero and the
supplyvoltage. Unearthed probes can causeserious electricshock.

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3.4 Atmospheres
When an optionalgas inletis fitted there is alabelnear theinletsaying"INERT GASONLY". In
practice inert or oxidising gases maybeused, but notcombustibleor toxicgases. Chamber
furnaces are notgas tight, so it should beunderstood thatgas usagemaybehigh, and thatthe
chamber is likelyalways to contain someair. Residualoxygen levels of1%are to beexpected.
3.5 ControlatLowTemperatures
Ifthefurnace is to beused attemperatures much lower than its design maximum, controlstability
can often beimproved byreducingthepower limit. Remember to makearecord oftheoriginal
settingbefore alteringthepower limit. Example:Itis desired to run thefurnace at300°C. The
normalcontrolsettings can beexpected to causeexcessiveovershootas thefurnace reaches
temperature. Tryasettingof40%, which should greatlyreduce this overshoot. Experimentmaybe
required to achieveagood result; avoid power limits belowabout30%, as controlaccuracyfalls
off atsuch levels. Notethatsettingthevalueto zero prevents thefurnace fromheating.
3.6 OperatorSafety
Thefurnace incorporates asafetyswitch which interrupts theheatingelementcircuit when the
dooris opened. This prevents theuser touchingaliveheatingelement, butalso prevents the
furnace fromheatingup ifthedooris leftopen. Theoperation ofthis switch should bechecked
periodically– see section 4.1.2.

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4.0 MAINTENANCE
4.1 GeneralMaintenance
Preventiverather than reactivemaintenance is to bepreferred. Thetypeand frequencydepends on
furnace use:thefollowingare recommended.
4.1.1 Cleaning
Sootdeposits mayforminsidethefurnace, dependingon theprocess. Atappropriateintervals
removethesebyheatingas indicated in section 3.2.
Thefurnace outer surface maybecleaned with adamp cloth. Do notallowwater to enter the
interiorofthecaseorchamber. Do notclean with organicsolvents.
4.1.2 Safety Switch
Thedoorswitch operation mentioned in 3.6 should bechecked periodicallyto ensure thatheating
elements are isolated when thedooris opened. In normalconditions thesafetyarrangementshould
outlastthefurnace, butit could beaffected byrough handling, acorrosiveenvironmentorwork
materials, orexceptionalfrequencyofuse.
Aqualified electrician should check thatthesupplyto theheatingelements is cut, with and
withoutpower beingon, when thedooris open partiallyand fully;it is importantthatisolation is
notjustmarginallyachieved. Thecheck is bestmadeon theelementterminals after removalofthe
furnace back:probingtheelementsurface insidethefurnace could beinconclusivebecauseof
surface oxidation. Notethatboth liveand neutralsides oftheelementshould beisolated when the
dooris opened.
4.2 Calibration
After prolonged usethecontroller and/orthermocouplecould require recalibration. This would be
importantforprocesses which require accuratetemperature readings orwhich usethefurnace
closeto its maximumtemperature. Aquick check usingan independentthermocoupleand
temperature indicatorshould bemadefromtimeto timeto determinewhether full calibration is
required.
Dependingon thecontroller, thecontroller manualmaycontain calibration instructions.
4.3 After Sales Service
Lenton’s service division (ThermalEngineeringServices)has ateamofService Engineers capable
ofrepair, calibration and preventivemaintenance offurnace and oven products atourcustomers’
premises throughouttheworld. Wealso sell spares bymail order. Atelephonecall orfaxoften
enables afault to bediagnosed and thenecessaryspare partdespatched.
Each furnace has its own record card atLenton. In all correspondence pleasequotetheserial
number, modeltypeand voltagegiven on theratinglabelofthefurnace. Theserialnumber and
modeltypeare also given on thefrontofthis bookletwhen supplied with afurnace.
To contactThermalEngineeringServices orLenton see theback pageofthis manual.
4.4 RecommendedSpares Kits
Lenton can supplyindividualspares, orakit oftheitems mostlikelyto berequired. Orderingakit
in advance can savetimein theeventofabreakdown.
When orderingspares pleasequotethemodeldetails as requested above.

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5.0 REPAIRS & REPLACEMENTS
5.1 Safety Warning – DisconnectionfromSupply
Always ensure thatthefurnace is disconnected fromthesupplybefore repairwork is
carried out.
5.2 Safety Warning -Refractory Fibrous Insulation
This furnace contains refractoryfibres in its thermalinsulation. Thesematerials may
bein theformoffibre blanketorfelt, vacuumformed board orshapes, mineralwool
slab orloosefill fibre.
Normaluseofthefurnace does notresult in anysignificantlevelofairbornedustfromthese
materials, butmuch higher levels maybeencountered duringmaintenance orrepair.
Whilstthere is no evidence ofanylongtermhealth hazards, westronglyrecommend thatsafety
precautions are taken whenever thematerials are handled.
Exposure to dustfromfibre whichhas beenusedathightemperatures may cause
respiratory disease.
Whenhandling fibre always useanapprovedmask, eyeprotection, gloves and long
sleevedclothing.
Avoidbreaking up waste material. Disposeofwaste fibre insealedcontainers.
After handling rinseexposedskinwithwater before washing gently withsoap(not
detergent). Washworkclothing separately.
Before commencinganymajorrepairs werecommend reference to theEuropean CeramicFibre
IndustryAssociation Bulletin No. 11 and theUK Health and SafetyExecutiveGuidance Note
EH46.
Wecan providefurther information on request. Alternativelyourservice division can quotefor
anyrepairs to becarried outatyourpremises orours.
5.3 Temperature Controller Replacement
2216, 2416, 2408 etc. Easeapartthetwo lugs attheside;grip theinstrumentand withdraw it from
its sleeve;push in thereplacement.
5.4 Solid-state Relay Replacement
Disconnectthefurnace fromthesupplyand removethecontrolpanel.
Makeanoteofthewire connections to thesolid staterelay, and disconnectthem.
Removethesolid staterelayfromits panelorbaseplate.
Replace and reconnectthesolid staterelayensuringthattheheat-conductingthermalpad is
sandwiched between therelayand thepanelorplate. Alternativelyathin layer ofwhite, heat-
conductingsilicon pastemaybeapplied between thenewrelayand thebase.
Thenewsolid staterelaycontains abuilt-in MOV which protects it fromshortperiods ofexcess
voltage. Iftheold relayhad aseparatedisc-shaped "MOV"connected between thehigh voltage
terminals oftheold relay, discard theold MOV.
Replace theremoved panel.
5.5 FuseReplacement
Fuses are marked on thecircuit diagram(section 7.1)with typecodes, e.g. F1, F2. Alistofthe
correctfuses is given in section 0. Fusetypes F2 and F3 maynotbefitted on this furnace.
Ifanyfusehas failed, it is advisableforan electrician to check theinternalcircuits.

EF,AF
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Replace anyfailed fuses with thecorrecttype. Forsafetyreasons do notfit larger capacityfuses
withoutfirstconsultingLenton.
Access is byremovalofthecontrolpanel.
5.6 ThermocoupleReplacement
Models EFand AFusethesametypeofthermocouple.
Disconnectthefurnace fromthesupply, and removetheback panel. Thethermocoupleenters the
chamber through theback in athin refractorytube, which is located in theback panelofthe
chamber box. Thewire tails are connected to asmall porcelain terminalblock on thechamber
back.
Makeanoteofthethermocoupleconnections. Thenegativelegofthethermocoupleis marked
blue. Compensatingcablecolourcodings are:
Negative:white
Positive(type‘K’):green
Disconnectthethermocouplefromits terminalblock, retain theporcelain beads, and withdraw it
fromtherefractorytube.
Fit thereplacementthermocouplewith beads and reconnect, observingthecolourcoding.
Refit theback paneland its earth wire ifdisconnected.
5.7 ElementReplacement– EF
See section 5.2-wearing a face maskis recommended.
TheEFchamber insulation is in 4 pieces:theheatingelementwhich forms thechamber top and
sides;thechamber back;blanketpackingaround theback;and thechamber baseboard.
Disconnectthefurnace fromthesupplyand removetheback panel.
Removethehearth tileifnecessary.
See section 5.6 abovethatrefers to thethermocouplecolourcodingand replacementinstructions.
Makeanoteofthethermocoupleconnections. Unfasten theconnections and removethe
thermocouple.
Disconnecttheelementtails and earth wire. Retain anyinsulation sleeves to refit later.
To removethechamber box, slacken the4 bolts on theunderside, then slidethechamber boxout
theback ofthecase. Becareful: thechamber is heavy.
Removethetop and back ofthechamber box.
Removethepackingblanketas necessary.
Liftouttheheatingelementand back insulation together. Theelementtails pass through theback
insulation. Gentlypull theback off theelementtails.
Ifnecessary, cutthetails ofthenewelementto match thelength oftheold.
Lineup thenewelementwith theback and push thetails through. Fit thenewelementand back
into thechamber box, replace thepackingblanket. Sometrimmingoftheelementmaybe
necessary.
Refit thechamber top and back.
Refit thechamber boxinto thecaseand retighten the4 bolts.
Refit and connectthethermocouple, elementtails with insulation sleeves, and earth wire.
Refit theback panelreconnectingits earth wire, and refit thechimney.

EF,AF
10 LF01
Switch thefurnace ON and heatto 900° withoutinterruption, then soak for1 hour. Somesmoke
maybeobserved duringthis process, which should becarried outin awell ventilated area.
Check thatthefurnace is controllingproperlyto ruleoutthepossibilitythattheprevious element
failed becauseofafault in thecontrolcircuit.
5.8 ElementReplacement– AF
See section 5.2-wearing a face maskis recommended.
TheAFchamber is formed bywindingresistance heatingwire on to arefractorymuffleformer. In
theeventoffailure, thewhole“wound muffle” assemblymustbereplaced.
Disconnectthefurnace fromthesupplyand removetheback paneland chimney.
See section 5.6 abovethatrefers to thethermocouplecolourcodingand replacementinstructions.
Makeanoteofthethermocoupleconnections. Unfasten theconnections and removethe
thermocouple.
Disconnecttheelementtails and earth wire. Retain anyinsulation sleeves to refit later.
To removethechamber box, slacken the4 bolts on theunderside, then slidethechamber boxout
theback ofthecase. Becareful: thechamber is heavy.
Removethetop and back ofthechamber box.
Removetheinsulation boards and brick pieces as necessaryto exposethemuffle, makingnoteof
theirlocation forrefitting. Removethemuffle.
Ifnecessary, cutthetails ofthenewelementto match thoseoftheold.
Fit thenewelementinto place.
Refit theinsulation boards and brick pieces.
Refit thechamber top and back.
Refit thechamber boxinto thecaseand retighten the4 bolts.
Refit and connectthethermocouple, elementtails with insulation sleeves, and earth wire.
Refit theback panelreconnectingits earth wire, and refit thechimney.
Switch thefurnace ON and heatto 900° withoutinterruption, then soak for1 hour. Somesmoke
maybeobserved duringthis process, which should becarried outin awell ventilated area.
Check thatthefurnace is controllingproperlyto ruleoutthepossibilitythattheprevious element
failed becauseofafault in thecontrolcircuit.