Sciencemadness Discussion Board - Fixing a broken heating mantle

Fixing a broken heating mantle

bahamuth - 9-4-2010 at 09:38

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.

Magpie - 9-4-2010 at 10:13

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.

Contrabasso - 11-4-2010 at 03:12

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.

chemrox - 11-4-2010 at 14:12

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.

bahamuth - 13-4-2010 at 14:24

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.

chemrox - 13-4-2010 at 23:46

Quote: Originally posted by bahamuth

Thanks for all the advise, but as it turns out I decided not to buy myself work...etc.

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).

peach - 1-5-2010 at 06:43

Quote: Originally posted by chemrox

Quote: Originally posted by bahamuth

Thanks for all the advise, but as it turns out I decided not to buy myself work...etc.

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]