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1 Copyright by Kanthal be reproduced only with proper acknowledgement of the 2 A 1 3 ISBN 91 86720 08 -25000 by Texter med Tryck AB and set in DTP by Mediaid , Eskilstuna. (180 ) Printed in Sweden by PRIMA tryck, Hallstahammar, information, which may be subjected to change, is offered solelyfor your consideration and should not be taken as a warranty orrepresentation for which we assume legal responsibility. It is not to beunderstood as permission or recommendation to practice a patentedinvention without a licence and the user should determine wetherrelevant patents exist.

2 Kanthal is a registered trademark of Kanthal Group companies inSweden and other foder 99-05-04 Sidan 1 KANTHALSUPERE lectric Heating ElementHandbookKANTHAL ABP O Box 502SE 734 27 Hallstahammar, SwedenTelephone: + 46 220 210 00 Fax : +46 220 211 Sandvik Company KSHB F rord s 1-8 99-05-10 Sidan 3 Kanthal AB, Hallstahammar, F rord s 1-8 99-05-10 Sidan 45 Kanthal Super HandbookIntroductionKANTHAL is a world-renowned name within the field ofelectric heating and you will find our handbook anindispensable aid when installing and operating our KANTHALSUPER resistance elements that are designed for all types ofelectric heated industrial we introduced the now world-famous Kanthal iron-chromium-aluminium electric resistance alloys in the earlythirties this represented a considerable rise in the maximumoperating temperature of metallic resistance.

3 When Kanthal SUPER elements were introduced in1956, this represented a step upwards on the temperature scalefor resistance aim of our R&D department, however, has always been toimprove our materials to enable their use at still highertemperatures. Through intense research work, we have been able to raisethis temperature from 1650 C (3000 F ) element temperaturein 1956, to 1850 C (3360 F ) element forms have also been developed and in thishandbook you will find information about SUPERTHAL hightemperature heating SUPER elements have proved to be very useful notonly at high furnace temperatures, but also at lowertemperatures, particularly in the field of heat treatment ofmetallic products in controlled atmospheres and melting fields of possible applications are unlimited and have yetto be fully investigated.

4 With the increasing interest in electricheating, we can expect many new designs and applications inthe future. In addition to information on the properties of our KANTHALSUPER material this handbook will also provide data on ourstandard elements and instructions for element calculation,installation, operation, etc. Further, advice is given on furnacedesigns, and some examples of actual Kanthal SUPER element installations are shown in the installation have tried to give you enough information to enable you tocalculate and install Kanthal SUPER elements and how tooperate furnaces.

5 If our advice is followed, you will be assured ofan efficient and economical installation for your special heattreatment you need any further advice, specialists at our companies,our agents and the skilled staff at our technical servicedepartment in Hallstahammar will be pleased to assist , Sweden 1999 Kanthal KSHB F rord s 1-8 99-05-10 Sidan 5 Contents6 Kanthal Super is Kanthal SUPER ..9 Quality and product summary .. and physical properties ..11 Chemical resistance ..123 Elements and elements ..17 Terminal shapes ..18 Two-shank bent elements.

6 20 Four-shank 1700 elements for horizontal use ..20 Tubes ..224 SUPERTHAL heating data for SUPERTHAL (Table 6) ..27 Temperature-loading diagram ..28 SUPERTHAL terminal design ..295 Electrical ..63 Temperature-loading diagram, Kanthal SUPER 1700 and 1800 ..64 Temperature-loading diagram, Kanthal SUPER 1900 ..65 Wall loading ..667 mounted elements ..67 Horizontally mounted elements ..67 Brick lined furnaces ..68 Ceramic fibre lined furnaces ..69 Element holders and anchor systems ..74 Contacts ..78 Assembling of Kanthal SUPER elements.

7 80 Assembling of SUPERTHAL furnaces ..85 Elements in radiant tubes ..868 of element calculations ..94 KSHB F rord s 1-8 99-05-10 Sidan 69 Control, power supply and Material characteristics ..107 Control in general ..107 Thyristor control ..108 Phase-angle firing ..108 Burst firing with phase-angle start ..109On/off control ..110 Tapped transformer ..110 Contactor switch, changing the element connection ..111 Scott-connected transformers ..114 Calculation of transformers ..114 Wiring to counteract electromagnetic forces ..11510 Furnace start-up procedure recommendations.

8 121 Starting up a newly-built furnace ..121 Replacement of elements ..122 Temperature control ..122 Standard platinum-platinum/rhodium thermocouples ..12311 Appendix ..125 Element size 3/6 and 4/9 ..125 Element size 6/12 ..127 Element size 9/18 ..130 Element size 12/24 ..132 Anchor systems ..134 Passage bricks ..136 Other accessories ..13912 Appendix ..145 Temperature colour ..146 Resistivity as a function of temperature for some resistor materials and for copper ..147 Physical data, gases ..148 Content of water, gases ..148 Average theoretical heat storage in kW/t for some common metals.

9 149 Physical data, metals ..150 Temperature conversion table ..152 Miscellaneous conversion factors ..154 Thermocouples ..156 Intensity of black body radiation ..157 Relative intensity of radiation of Kanthal SUPER ..158 Heat transfer by radiation ..159 Calculation of furnace insulation ..160 ContentsKanthal Super Handbook7 Fig. 1 Range of Kanthal SUPER 6/12, 9/18, 12/24 elements and SUPERTHAL heating 2 Range of Kanthal SUPER 3/6 and 4/9 is Kanthal SUPERC ompositionKANTHAL SUPER is a dense cermet material consisting of MoSi2and an oxide component, mainly a glass phase.

10 Kanthal SUPER has the ability to withstand oxidation athigh temperatures. This is due to the formation of a thin andadhesive protective layer of quartz glass on the surface. WhenMoSi2reacts with oxygen in the atmosphere, the layer of quartzglass is formed and under this a thin layer of molybdenumsilicide with a lower silicon content Kanthal SUPER elements are operated attemperatures around 1200 C (2190 F ) the material becomesductile, whilst at lower temperatures the material is more silica layer possesses the capacity to clean itself fromadhering impurities.