Sciencemadness Discussion Board

Smoking heating mantles?

aonomus - 25-7-2010 at 11:35

A friend of mine was clearing out a section of his lab recently and found an old replacement heating mantle element still in its original packaging and gave it to me. I hooked it up to a light dimmer and slowly turned it up to warm up a RBF for a distillation. It started smoking and turning a brown colour whenever it was exposed to air, so I cut power and swapped to a oil bath to finish the job for now.

Any thoughts as to why it was smoking like that? Since its brand new it couldn't be some spilled chemical on it, so I'm wondering if its something in the element itself, or some processing material they coated the fiberglass with during manufacturing.

I do have a variac, its just big, heavy, 15A rated and simply too much trouble if I can avoid it.

peach - 25-7-2010 at 15:06

It'll be residues on it that would normally burn off the first time it's used or someone has spilled something on it in the past.

Put it outside and warm it up.

Hopefully, it'll start smoking again and eventually stop. Or, it'll burst into flames. If the latter occurs, it was never meant to be.

rrkss - 25-7-2010 at 20:36

Most new mantles smoke and discolour the first time you use them. My new mantle required me to boil water for at least 10 minutes in a roundbottom to bake it out whne I bought it.

aonomus - 25-7-2010 at 20:57

I think tomorrow I will set it up again in the backyard with a RBF full of water with a vigreux column on top for air-cooled reflux, and bake it out gently.

rrkss - 25-7-2010 at 21:53

Quote: Originally posted by aonomus  
I think tomorrow I will set it up again in the backyard with a RBF full of water with a vigreux column on top for air-cooled reflux, and bake it out gently.


Sounds like a good idea.

aonomus - 26-7-2010 at 18:14

Even on a 50% setting and 20 minutes of heating, it still smoked. Didn't get to the point of boiling water though. I might give it another shot tomorrow when I have more time.

peach - 26-7-2010 at 18:55

Run it up to 100%.

If it's going to go, it's already gone. You just need to confirm it.

20 minutes of smoke is annoying. Although, I wasn't there to see it, so I don't know how bad it is. Does the smoke have any particular smell, like burning plastic, insulation or oil?

[Edited on 27-7-2010 by peach]

Sedit - 26-7-2010 at 18:56

Does the smoke have any smell that may indicate it to be a preservative coating added to protect the elements on storage?

aonomus - 26-7-2010 at 20:13

I tried to avoid breathing the smoke where I could. It had a acrid odour/taste that smelled more of burning plastic, though it may be some sort of coating. It left a residue on the RBF too.

Well, if its worth doing its worth overdoing, I'll just max it out and see what happens...

[Edited on 27-7-2010 by aonomus]

rrkss - 26-7-2010 at 23:04

The residue should come off with just soap and water. Run the mantle for an hour or so and the smoking should stop.
Quote:

Bake-out Procedure for New Heating Mantles
On the initial heat-up of the mantles, a slight odor may be detected and some discoloration will occur in
the cavity area. The discoloration of the cavity area has no effect on the operation of the mantle. If the
heated vessel becomes discolored, it can be cleaned with water. To bake-out your mantle prior to use,
connect the mantle to your temperature controller and fill a flask corresponding to the size of the mantle
half full of water. Place the flask in the mantle cavity and allow the water to come to a boil and continue
boiling for approximately 15 minutes. The mantle can be operated at full rated voltage during bake-out.

chemrox - 27-7-2010 at 20:45

@rrkss Nice post; let's archive it somewhere accessible

aonomus - 1-8-2010 at 14:27

Left it for 30 minutes on full, continued to have that odor. There was one spot on the underside of the mantle that appears to have turned a darker brown. It hasn't exploded into flames or started sparking out, but on the other hand it is impossible to use it indoors without a fume hood, and even then without making the neighbors think that a fire is nearby. Seems like a writeoff, oh well.

peach - 1-8-2010 at 15:13

If it's a write off, right... bake the living shit out of it. Maybe stick a fan on it and leave it on full for hours.

watson.fawkes - 1-8-2010 at 15:34

Quote: Originally posted by aonomus  
Since its brand new it couldn't be some spilled chemical on it, so I'm wondering if its something in the element itself, or some processing material they coated the fiberglass with during manufacturing.
Since it's still smoking, you might conclude that something was spilled on it during manufacture; it's not like quality control is perfect. It might be an excess of something that was supposed to be on there, but got too much of it.

Chainhit222 - 1-8-2010 at 16:20

heat that shit up with a blow torch, but damn it must smell hella bad if your neighbors can smell it, is it emitting massive plumes of black smoke?

[Edited on 2-8-2010 by Chainhit222]

peach - 1-8-2010 at 16:47

Quote: Originally posted by watson.fawkes  
Quote: Originally posted by aonomus  
Since its brand new it couldn't be some spilled chemical on it, so I'm wondering if its something in the element itself, or some processing material they coated the fiberglass with during manufacturing.
Since it's still smoking, you might conclude that something was spilled on it during manufacture; it's not like quality control is perfect. It might be an excess of something that was supposed to be on there, but got too much of it.


That's kind of what I thought. Someone may have spilled something on it and put it back in the box, or spilled something on the box. I'd vote roast the shit out of it. As I've said, a few times, if it was an electrical fault, it'd have gone up by now. There's something on the mantle. Ramp it up to full and let it roast. Sometimes there only needs to be a few drops of something there for it to smoke / fume for hours. Cook it. If it's dead, it's dead. If it's going to ever work, it'll come through fine.

rrkss - 2-8-2010 at 03:54

It took one of my mantles two full distillations of nitric acid azeotrope before the smoking stopped. Just keep baking it out outside with a flask in it containing water so the unit does not overheat and burn out. The smell should go away eventually.

alphacheese - 13-3-2012 at 13:15

So why do they smoke like that? I just got a brand new 1000mL heating mantle and it started smoking after a couple hours of my first time using it. I didn't spill anything on or in it and there was dark residue all over my RBBF too. It's not smoking tremendously but now the fabric is starting to get more and more brown. Brand new, no spills, what gives?

Endimion17 - 13-3-2012 at 14:59

I'd try to wash it with alcohol first. Then drying on air, then baking.