bahamuth
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Fixing a broken heating mantle
I am currently in a position to acquire a heating mantle which is said to be broken, e.g. do not heat up, for a cheap sum.
So my question is, is it any point to buy it and try to fix it; might just be a connection issue in the power cord or as well a fatal element
burnout.
Perhaps some of you have attempted anything similar and/or have pix of how it looks like inside so I might judge if i want to try to fix it..?
Am quite skilled in fixing things, electric or mechanic but wanted advise first.
Any sufficiently advanced technology is indistinguishable from magic.
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Magpie
lab constructor
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I have repaired a broken heating element for a mantle. It can't be soldered as it get's too hot in use. Use a very small ss crimp.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Contrabasso
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Probably it's repairable, there could be faults in the controller, connections, cables or the element itself. Too many options to give a definitive
answer. If it's old then beware asbestos -maybe don't play with it then. If it's been soaked with corrosive chems then the element may actually be
dissolved and missing.
Evaluate your time and the cost of the thing against the cost of a new mantle.
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chemrox
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Glascol folks warned me against trying to repair one that I overheated long ago. I asked them if they could do it and they said "no." There are some
cases where you might be able to fix one eg one with a built in rheostat that isn't working. If I were you I'd simplify life and find a working one
the size you need on ebay or labx. I've been collecting used ones for years and have them in every size from 50 ml to 3L as well as ones for funnels,
sep funnels and a heating jacket for a 500 mm column.
A couple of tips: never leave them on without the right size vessel in them, never put them in place before loading the flask with the main
reactant(s) and solvents and always watch the reaction until an equilibrium is reached. Last year I left the room after turning one way up to get the
reaction moving more quickly then I got a call and by the time I got back the lab was full of smoke and my bench was covered with dark goo. The
mantle was, of course ruined.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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bahamuth
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Thanks for all the advise, but as it turns out I decided not to buy myself work.
But needed a large mantle and flask for distilling an endless supply of chloroform from Bligh & Dyer waste, contains to much methanol and water to
be used for anything right now.
But some advise i got elsewhere about fixing the mantle, perhaps one could buy insulated Nichrome wire and just stitch it in there with glass thread
like the ones they use on boat/truck engine manifolds insulation. This could be a fix if the element was corroded or just melted of. And one would
have to calculate the wattage on the inserted Nichrome.
And also, it is kinda hard to get any lab equipment in Norway, got most of mine from ebay but all the right sized mantles are 110 volt from the US and
we have 220 and I do not bother to make/buy a transformer.
Any sufficiently advanced technology is indistinguishable from magic.
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chemrox
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Good decision. May I suggest using an oil bath. I bought a deep fat fryer that will heat flasks up to 3L. The controller on it will hold any
temperature I set it to within 1-2 degrees C. I believe its filled with diethyl phthalate, bp 295C (wiki).
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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peach
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Quote: Originally posted by chemrox  |
Good decision. May I suggest using an oil bath. I bought a deep fat fryer that will heat flasks up to 3L. The controller on it will hold any
temperature I set it to within 1-2 degrees C. I believe its filled with diethyl phthalate, bp 295C (wiki). |
I second that suggestion.
I once incinerated one of IKA's top of the line stir / hotplates when I was rushing and plugged it into the socket running at the wrong voltage. It
glowed for about three seconds, then left me for ever. Think it cost about 1k... oooowwww.............
You'd think they could stick a universal SMPS in it for that much. I cracked it open when it died. First of all, I wasn't blown away by the
electronics within. There only seemed to be one resistor that'd burnt out, but it was an SMT / SMD and I couldn't see any markings on it even under
our electronics lab's SMT / SMD gear; and the technicians I asked for help where the Sauron, Nicodem & Klute when it came to working on things
like this. Our lab did nanotech work, enough said. IKA refused to tell me what the values of it were. "It's not our fault you burnt it out." I seem to
remember hearing. Followed by something like "Give use $250 - 300 for a new PCB, and a few more hundred if you want to keep running it on that
socket". The resistor would have been about 1 cent or less to replace. Not what I was saying, but fuck you too IKA.
IKA supply government funded labs with blank checks.
A deep fat fryer and a thermometer will do you better than an IKA. IKA's even have external temperature probes to check the solution temperature, so
you're not loosing out by using a mercury thermometer to track the temperature at all. And it costs literally an order of magnitude or two less.
I have a cheaper no name hotplate name that makes an annoying scuffing sound when it gets hot and the none concentric magnet starts rubbing against
the enclosure, but I'm positive I could carry out most of the work I do straight on the hotplate of an oven. The only advantage is the stir bar
features.
With Chemrox claiming a 1-2C variation in his temperature, that's good! Perfectly usable for chemistry and probably better than some hotplates can
manage. If I remember rightly, my super expensive IKA could only manage 1C resolution on the settings.
Deep fat fryer and a thermometer any day. If I was doing it all again, I'd go straight to overhead stirring as well; there are threads on hear about
DIYing your own overhead stirrer too.
[Edited on 1-5-2010 by peach]
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