Folks,
my old heating mantle is dead. There’s a hole in the sleeve fabric and the resistive wire inside has been cut. Worse, there is a fugitive leak to
the earth that sets off the circuit breaker every time I try to turn the appliance on.
Anyways. I dismounted the whole thing and extracted the faulty sleeve. Now I need a spare part, but I’m not sure where to turn to. I've asked the
company that sold it to me in the first place, but I’m not sure if they handle repairs or not. Do you have any idea where I could find a spare
sleeve? It’s a 220 V, ø 9 cm, 150 W. Also, it has a built-in PT100 temperature sensor for regulation…
[EDIT: Picture of the hole.]
Thanks!
[Edited on 22-12-2024 by Keras]fx-991ex - 22-12-2024 at 08:46
deschem on ebay has mantle sleeve(other vendor probably do too), make sure the voltage and wattage and size are the same, i dont see any reason why it
would not fit.
[Edited on 22-12-2024 by fx-991ex]Keras - 22-12-2024 at 08:54
deschem on ebay has mantle sleeve(other vendor probably do too), make sure the voltage and wattage and size are the same, i dont see any reason why it
would not fit.
Well, as I suddenly realise, I forgot to mention I need a sleeve with a PT100 sensor for the regulation. But thanks for the suggestion.
[EDIT: Found out someone near me sells the same model on EBay for ¼ of the price. Might simply buy a second-hand one and keep this one for spare
parts.]
[Edited on 22-12-2024 by Keras]
Some thoughts
Sulaiman - 22-12-2024 at 23:08
1) I would start by finding the earth leakage problem,
hopefully it is just related to the basket which needs repair anyway.
Unplug, open, disconnect BOTH ends of the nichrome wire, make safe any wires or connectors modified, power on, hopefully ok
(or watch for where the smoke comes from)
2) the heating sleeve is just nichrome wire woven onto a glass fibre woven basket.
3) power = V2/R, R is proportional to the length of nichrome wire,
Power is inversely proportional to wire length.
So even if a repair means that if only half of the length remains in use,
the power will only be doubled.
3) nichrome wire needs to be either welded, or in a compression joint as solder may melt.
4) if you can find a suitable replacement heating element/liner/basket then I'm fairly confident that the existing probe can be inserted / re-used
5) I think that soaking/rinsing a heating element basket with tap water would dissolve away any ionic/conductive salts without harm to the glass
fibres or nichrome wire. Thoroughly dry before re-use.
But I have not tried.Keras - 23-12-2024 at 00:51
Yeah, the leakage was caused by the nichrome wire being exposed. With the heating element removed, nothing happens. Also in hindsight, the hole was
probably caused by sputtering from an alkaline fusion reaction. I used this mantle to heat potassium hydroxide to ~ 300 °C in order to make either
p-cresol from sodium p-toluenesulphonate or ß-naphthol from ß-naphthalenesulphonate. At this temperature, a drop landing on the glass tissue would
easily eat through it and dissolve the wire.
Unfortunately I could not salvage the PT100 sensor. It is very tightly stitched/woven into the sleeve, much like the nichrome wire itself. It cannot
be extracted, I had to cut the wires.
This particular heating mantle seems to be fairly common (OEM part). It is sold under various brand names. Temperature control is darn accurate, a
fact I chalk up to the tight integration of the temperature probe into the sleeve. Unfortunately, it lacks magnetic stirring (well, some models have
it, but they are really expensive), which makes it impractical to use in several situations where strong stirring/mixing of the reactants is
mandatory.
In any case, I ordered one of the second-hand batch I found on eBay – what a fluke! The seller sold it for € 60 instead of ~ € 250 brand new, so
that was really a snip, especially considering the second-hand parts look almost fresh from the factory. I’ll just have to calibrate mine, using my
PT100 sensor simulator.
