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BLF 

 

 

5.6  Element Installation & Replacement 

Safety Warning – Molybdenum Disilicide elements.  

The elements form a glazed surface when heated. Internal stresses can form 
through heating and cooling which render the glaze fragile. The glaze can 
sometimes splinter into a shower of sharp particles when handled. Always wear 
eye protection when handling the elements.

 

 

Remove the element access cover (see section 2.3). 

 

Remove the aluminium braids and clips using fingers or the clip tool provided, depending on the 
type of clip (or remove the combined clips and braids, if supplied). Lift out the old element and 
the insulation block: handle the block with care as it is fragile. Remove the clamps. 

 

Handle the new heating elements with extreme care as they are very fragile. Also, avoid touching 
the heating surface (the thin part of the element). Carefully unpack the elements and slide over 
them the insulation blocks. Fix the clamps so that the length of element leg above them is 30mm 
(most models) or  45mm (BLF 17/8). 

 

Insert the new element; refer to the element connection diagram. Single phase models have all the 
elements connected in series. Reconnect the braids. Ensure that no braids of clips are touching 
each other or touching any other furnace parts. 

 

After installing new elements run the furnace at 1500°C for an hour. This creates a protective 
glaze on the element surface. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Use of Clip Tool 

larger clips require clip tool, comprising  
two levers 

 

 

smaller clips do no require clip tool 

 

6.0 

MF23 

11 

Summary of Contents for BLF 17/3

Page 1: ...ual is for the guidance of operators of the above products and should be read before the furnace is connected to the electricity supply 7 4 CONTENTS Section page 1 0 Symbols Warnings 2 2 0 Installation 4 3 0 Operation 6 4 0 Maintenance 9 5 0 Repairs Replacements 9 6 0 Fault Analysis 11 7 0 Circuit Diagrams 13 MF23 ...

Page 2: ...ange of the ancillary equipment a transformer is included in the control circuit as shown Power Control 15 Manuals for the furnace controller and overtemperature controller are supplied separately 9 0 Specifications 17 Please read the controller manuals before operating the furnace 1 0 2 MF23 ...

Page 3: ... Heat Light the adjacent light glows or flashes to indicate that power is being supplied to the elements 1 2 Warning Symbols DANGER of electrical shock read any warning printed by this symbol DANGER hot surface Read any warning printed by this symbol WARNING all surfaces of a furnace may be hot DANGER read any warning printed by this symbol 2 0 MF23 3 ...

Page 4: ...d from the electrical supply see below 2 3 Fitting the Heating Elements Wear eye protection when handling the heating elements See the warning in section 5 6 The Molybdenum Disilicide elements are EXCEPTIONALLY FRAGILE and are packed separately together with other items as shown in the list separately packed items Most models BLF 17 8 Elements 6 9 Element clamps 6 18 Element clips 12 18 Braids 1 s...

Page 5: ... internal supply rated fuses and a permanent connection should be made from a fused and isolated supply to the internal terminals after temporary removal of the furnace back panel The supply point must be within reach of the furnace operator and must incorporate either an isolating switch which operates on both conductors single phase or on all live conductors two three phase or a quickly removabl...

Page 6: ... resetting the overtemperature controller according to the instructions supplied To switch the furnace off set the Instrument switch to off The case cooling fans remain on and the chamber can be unloaded Leave the fans on until the furnace cools to below 300 C If the furnace is to be left off isolate it from the electrical supply 3 2 General Operating Advice Heating element life is shortened by us...

Page 7: ...element circuit when the hearth is opened This prevents the user touching a live heating element but also prevents the furnace from heating up if the hearth is left open Avoid burns Carbolite can supply tongs face masks and heat resistant gloves Before you remove a hot object from the furnace make sure you have a safe place to put it down When the hearth is lowered with the furnace hot there is co...

Page 8: ...te tongs are available before starting Clamp Option This option assists the placing of the crucible over tall workpieces The clamp is provided in the form of a support shelf which can be fitted to a hinge on the case and a pair of insulated tongs With the hearth lowered place the support shelf on the hinge and swing to the side Use the tongs to lift the crucible up into the chamber swing the shelf...

Page 9: ...klet when supplied with a furnace To contact Thermal Engineering Services or Carbolite see the back page of this manual 4 4 Recommended Spares Kits Carbolite can supply individual spares or a kit of the items most likely to be required Ordering a kit in advance can save time in the event of a breakdown Each kit comprises one thermocouple one sheath one power thyristor one door insulation piece a s...

Page 10: ... commencing any major repairs we recommend reference to the European Ceramic Fibre Industry Association Bulletin No 11 and the UK Health and Safety Executive Guidance Note EH46 We can provide further information on request Alternatively our service division can quote for any repairs to be carried out at your premises or ours 5 3 Temperature Controller Replacement 2216 2416 2408 etc Ease apart the ...

Page 11: ... care as it is fragile Remove the clamps Handle the new heating elements with extreme care as they are very fragile Also avoid touching the heating surface the thin part of the element Carefully unpack the elements and slide over them the insulation blocks Fix the clamps so that the length of element leg above them is 30mm most models or 45mm BLF 17 8 Insert the new element refer to the element co...

Page 12: ...ler may be faulty or not receiving a supply due to a faulty switch or a wiring fault Æ The SUPPLY light is OFF Æ Check the supply fuses and any fuses in the furnace control compartment B Furnace Overheats 1 The HEAT light goes OFF with the instrument switch Æ The controller shows a very high temperature Æ The controller is faulty Æ The controller shows a low temperature Æ The thermocouple may have...

Page 13: ...BLF CIRCUIT DIAGRAMS 7 1 Single Phase GR Y Green Yellow R Red TC temperature programmer BU Blue OTC overtemperature controller P Pink G Grey MF23 13 ...

Page 14: ...BLF 7 2 Three Phase with Neutral 7 3 Three Phase without neutral Delta 14 MF23 ...

Page 15: ...ply light Instrument Switch Filter if fitted 7 4 Lower Higher Voltages e g 208V 254V Where the supply voltage is outside the operating range of the ancillary equipment a transformer is included in the control circuit as shown 8 0 MF23 15 ...

Page 16: ...se rating for the various models 8 2 Power Control The setting for the power limit parameter in the controller OP Hi should be 100 for all models The thyristor stacks are set to the secondary element maximum currents given in the table TABLE OF FUSE AND CURRENT LIMIT VALUES Model Phases volts supply fuse rating type thyristor fuse rating current limit element circuit BLF 17 3 1 phase 220 240V 30 3...

Page 17: ...l 41 41 541 5877 Fax 41 41 541 5878 Email General Information Sales info kesn ch Accounts Department accounts kesn ch USA Office 233 Rogue River Highway 425 Grants Pass Oregon 97527 5429 USA Tel 1 503 206 0941 Fax 1 541 610 1646 Email General Information Sales info keison com Accounts Department accounts keison com Latin America Office World Trade Centre Apartado 0832 00708 Ciudad de Panamá República ...

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