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Thread: 1300 C

  1. #1 1300 C 
    Forum Freshman KYPOWERLIFTER's Avatar
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    I posted this topic elsewhere but it seems to have fallen stillborn from my typewriter. Perhaps I could get some advice/encouragement, here.

    I plan on producing a laboratory tube furnace capable of = to or > 1300 C. Does anyone have any experience working with materials designed for these temps?

    I have been pricing Mullite tubes: 500 mm L; ~34 ID; ~40mm OD, 18 G Kanthal A-1 wire (to be wrapped around the tube), Kaowool insulation blanket, and a piece of 'stove pipe' to be the outer tube.

    Right now I have two questions:

    1) Any suggestions as to the above components? By that I mean suggestions, as to better (in terms of quality and ability to take temperature), grades/types?

    2) I need to purchase a thermocouple and thermometer. Recommendations? I also need to design a circuit to adjust power to the wire. What would you guys do and how would you arrange it? I was thinking some sort of dimmer switch (have to handle 2000W power @ 230V) parallel with a bulb as indicator?

    Bear with me... When I get it going I'll make a how-to thread with pictures.


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  3. #2 Re: 1300 C 
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    Quote Originally Posted by KYPOWERLIFTER
    I posted this topic elsewhere but it seems to have fallen stillborn from my typewriter. Perhaps I could get some advice/encouragement, here.

    I plan on producing a laboratory tube furnace capable of = to or > 1300 C. Does anyone have any experience working with materials designed for these temps?

    I have been pricing Mullite tubes: 500 mm L; ~34 ID; ~40mm OD, 18 G Kanthal A-1 wire (to be wrapped around the tube), Kaowool insulation blanket, and a piece of 'stove pipe' to be the outer tube.

    Right now I have two questions:

    1) Any suggestions as to the above components? By that I mean suggestions, as to better (in terms of quality and ability to take temperature), grades/types?

    2) I need to purchase a thermocouple and thermometer. Recommendations? I also need to design a circuit to adjust power to the wire. What would you guys do and how would you arrange it? I was thinking some sort of dimmer switch (have to handle 2000W power @ 230V) parallel with a bulb as indicator?

    Bear with me... When I get it going I'll make a how-to thread with pictures.
    Although electric heaters can and do, go higher then 1300 centigrade. They are usually useful, and long lasting, up to about 2350 Fahrenheit or cone ten. Like in a ceramics kiln. If you go higher, you risk serious ARC and self destruction. Even explosion. Like a lightning strike.

    Many people go with gas kilns for this reason. Even though the risk of a gas explosion is real.

    What helps the electric kiln is the sulphur dioxide fire brick. It protects the metal parts of the kiln from breaks in the element. That occur over time. I used to manufacture three phase electrical equipment and, when heaters go, not even fast acting fuses can just take them right off line. However fast acting fuses do blow over time.

    Watlow has some heaters that go up just above 1200 degrees Centigrade. However if you go much hotter. You risk molten metal surfaces. Something that can be very dangerous.

    http://www.watlow.com/products/heaters/ht_multi.cfm

    It is not that the element will not go higher. It will. It is just that it becomes unstable.

    I use a MIG welder and a spool gun. If I change the polarity on the machine, and try to run the machine, allowing the metal wire electrode to emit electrons, from the power supply. It will not weld, at the machines maximum setting.

    But if I correctly charge the metal electrode so that, it pulls in electrons, and melts, it becomes a molten electrode. It beams rays back against the power supply that melts the metal part. With as much as ten to twenty times the heat.

    Even though the DC power supply is not even going in that direction. That is why they limit the elements temperature.



    Sincerely,


    William McCormick


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  4. #3 Re: 1300 C 
    Forum Freshman KYPOWERLIFTER's Avatar
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    Quote Originally Posted by William McCormick
    Although electric heaters can and do, go higher then 1300 centigrade. They are usually useful, and long lasting, up to about 2350 Fahrenheit or cone ten. Like in a ceramics kiln. If you go higher, you risk serious ARC and self destruction. Even explosion. Like a lightning strike.

    Many people go with gas kilns for this reason. Even though the risk of a gas explosion is real.

    What helps the electric kiln is the sulphur dioxide fire brick. It protects the metal parts of the kiln from breaks in the element. That occur over time. I used to manufacture three phase electrical equipment and, when heaters go, not even fast acting fuses can just take them right off line. However fast acting fuses do blow over time.

    Watlow has some heaters that go up just above 1200 degrees Centigrade. However if you go much hotter. You risk molten metal surfaces. Something that can be very dangerous.

    http://www.watlow.com/products/heaters/ht_multi.cfm

    It is not that the element will not go higher. It will. It is just that it becomes unstable.

    I use a MIG welder and a spool gun. If change the polarity on the machine, and try to run the machine, allowing the metal wire electrode to emit electrons, from the power supply. It will not weld, at the machines maximum setting.

    But if I correctly charge the metal electrode so that, it pulls in electrons, and melts, it becomes a molten electrode. It beams rays back against the power supply that melts the metal part. With as much as ten to twenty times the heat.

    Even though the DC power supply is not even going in that direction. That is why they limit the elements temperature.



    Sincerely,


    William McCormick
    Hm... There are numerous lab furnaces that are produced pretty much the same way. Maybe I'm not following... are you typing that the wire itself will not hold up to the heat, that will incur breaks/ARCS? I was working under the assumption that the Kanthal A-1 (18g) can take it? The wire will be acting as the 'element'. Granted Brauer, in "The Handbook of Preparative Chemistry", does not mention quite the temps I am referencing, but outlines the procedure.

    I was considering SO3 for oleum and even calcium phosphate to vaporized P4.
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  5. #4 Re: 1300 C 
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    Quote Originally Posted by KYPOWERLIFTER
    Quote Originally Posted by William McCormick
    Although electric heaters can and do, go higher then 1300 centigrade. They are usually useful, and long lasting, up to about 2350 Fahrenheit or cone ten. Like in a ceramics kiln. If you go higher, you risk serious ARC and self destruction. Even explosion. Like a lightning strike.

    Many people go with gas kilns for this reason. Even though the risk of a gas explosion is real.

    What helps the electric kiln is the sulphur dioxide fire brick. It protects the metal parts of the kiln from breaks in the element. That occur over time. I used to manufacture three phase electrical equipment and, when heaters go, not even fast acting fuses can just take them right off line. However fast acting fuses do blow over time.

    Watlow has some heaters that go up just above 1200 degrees Centigrade. However if you go much hotter. You risk molten metal surfaces. Something that can be very dangerous.

    http://www.watlow.com/products/heaters/ht_multi.cfm

    It is not that the element will not go higher. It will. It is just that it becomes unstable.

    I use a MIG welder and a spool gun. If change the polarity on the machine, and try to run the machine, allowing the metal wire electrode to emit electrons, from the power supply. It will not weld, at the machines maximum setting.

    But if I correctly charge the metal electrode so that, it pulls in electrons, and melts, it becomes a molten electrode. It beams rays back against the power supply that melts the metal part. With as much as ten to twenty times the heat.

    Even though the DC power supply is not even going in that direction. That is why they limit the elements temperature.



    Sincerely,


    William McCormick
    Hm... There are numerous lab furnaces that are produced pretty much the same way. Maybe I'm not following... are you typing that the wire itself will not hold up to the heat, that will incur breaks/ARCS? I was working under the assumption that the Kanthal A-1 (18g) can take it? The wire will be acting as the 'element'. Granted Brauer, in "The Handbook of Preparative Chemistry", does not mention quite the temps I am referencing, but outlines the procedure.

    I was considering SO3 for oleum and even calcium phosphate to vaporized P4.
    You are right at the temperature that ordinary metal goes molten.

    If the element is tiny and you have safe guards. I would not worry much. Look at a light bulb. Everything, the bulb holder, the wire, feeding it, is over sized compared to the element. But if you blow a light bulb you can pick up the spike with an oscilloscope.

    Now if you blow a giant light bulb, your heating element. You could get a giant spike. That can leave the system, because it was not part of the system. It can also do some serious cutting and welding.

    We use high frequency in our welders. It is harmless, I can pass it over my hand and it has no effect on me. Yet if touched to a piece of equipment, it can cause grounded boxes to arc to the, hot AC wire. And it can burn and do considerable damage. Using the amperage of the AC current, along with the starting ARC power of the high frequency. All because the high frequency is not going anywhere. It is not part of a loop. It is free, ARC power. It is trying to get to everything.

    I thought that everyone knew that when you break a wire the voltage goes way up from the ARC. That I was taught by a super, Marine Corp. Technician, that worked on super weapons, to boil subs in the ocean, was (Anode, Rectified, Cathode). My point is not to force this on anyone. But rather make it available to all.



    Sincerely,


    William McCormick
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  6. #5  
    Forum Freshman KYPOWERLIFTER's Avatar
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    I guess I fail to grasp the relevance. The 'element' will be insulated by a kaowool ceramic insulated blanket and the wire should in no way "break". Did you read the relevant passage from the wonderful book that I referenced? It makes it all very clear, I am not re-inventing the wheel. I am trying to craft a tube furnace precisely as they have been used in labs for decades.

    The beginning of your last paragraph seems to be insulting? I could easily point out to you that the way I have described has worked often and that I thought everyone here knew that, as it's not difficult to find numerous examples of them via google. I'm not clear why you would want to insult my admittedly limited knowledge but to do so by ignoring the tens of thousands of tube furnaces that have been produced by lab equipment suppliers seems strange.

    Sure, I posted a query as to materials and suggestions as to overbuilding as well as a question as to thermocouples, etc. but I am not interested in a kiln and if I were I could craft one... using refractory material and an iron pail with a second one to provide a downdraft, and MAPP gas as source of heat.
    Le silence éternel de ces espaces infinis m'effraie.

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  7. #6  
    Administrator KALSTER's Avatar
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    Sorry KYPOWERLIFTER, but William is not all there. He has weird and not so wonderful ideas about seemingly everything. I'd advise you to just ignore him as you would be hard pressed to get any sense out of him. Unfortunately I can't help you with your project, but good luck none the less!
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  8. #7  
    Forum Isotope Bunbury's Avatar
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    1300C is getting up there. We deal with temperatures in this range in Claus fiurnaces which are much larger than your project. Typically we use a multilayer refractory system with 90 or 94% alumina brick as the hot face, backed up by insulating brick and then some ceramic paper. The outer shell is carbon steel, and there is a shroud offset from the shell by 100 to 150 mm to induce cooling air flow.

    Your Kaowool blanket should be rated for the temperature you expect at the outside of the mullite pipe, so you need to calculate the temperature drop through the layers and make sure your mullite is thick enough. Consider ceramic paper but I'm not sure you can place it right on top of your mullite. A stainless steel stovepipe would give some lagniappe. If it's a fairly small project you might also consider a cooling air fan to drop the steel temperature.

    Good luck.
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  9. #8  
    Forum Freshman KYPOWERLIFTER's Avatar
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    KALSTER: Thanks for the heads-up. I appreciate it.

    Bunbury: Roger that! I will look into it.

    I neglected to mention this but I plan on coating the wire with ITC 100 HT.

    I will attempt this project in a couple of weeks... gotta keep brushing up on electricity
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  10. #9  
    Forum Freshman KYPOWERLIFTER's Avatar
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    Well...

    I have located two Mullite tubes; one @ 83.00 and one @ 86.00

    Kanthal A-1 Wire @ 15.00-20.00

    ITC 100 HT ceramic paste @ 38.00

    Kaowool 1" 2600F 2 ft2 @ 13.50

    Variac (for temp control) ebay searching ~100.00

    Stove pipe... 10.00-15.00

    Thermocouple and thermometer with the TP 04 thermocouple 89.99 http://cgi.ebay.ca/ws/eBayISAPI.dll?...:X:RTQ:CA:1123

    Quartz glass test tube (with ground glass joint) for use inside furnace... ~100.00

    I need to find a glassblower, I assume.

    Suggestions/Thoughts?

    [Thanks to 'Harold' for his suggestions]
    Le silence éternel de ces espaces infinis m'effraie.

    -Pascal
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