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Author: Subject: 1st hotplate stirrer
Housane
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[*] posted on 7-6-2020 at 09:10
1st hotplate stirrer


Hi all

I am looking to get my first hotplate stirrer and wondering if you have any recommendations, I was looking at this one https://www.amazon.co.uk/HUKOER-Magnetic-Stirrer-Laboratory-... does anyone have any better ideas? Is thin likely to work well?

Thanks in advance

Housane




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XeonTheMGPony
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[*] posted on 7-6-2020 at 09:18


general rule nothing under 600watts heating power is recomended
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SWIM
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[*] posted on 7-6-2020 at 10:31


One other important factor in choosing a hotplate is temperature range.

Usually not a problem, but this one says RT to 100C.
This means it won't reflux toluene, or even distill water at a reasonable rate.
You could leave the sensor out of the reaction mixture so it just runs constantly to get higher temperatures perhaps,but not sure if you could moderate that because the electronics probably wouldn't like being plugged into a rheostat.

Control of the reaction temperature is important, but in most organic reactions the temperature is regulated by the boiling point of the reaction mixture.

This sort of thing could be handy for more delicate reactions where they keep things below the boiling point, but those aren't really as common.

It can help to put the power requirements in perspective to compare these things to household appliances.
Small electric rice cookers are often around 250-400 Watts.

See if anybody you know has one in that range so you can throw some water in there, heat it up, and watch to see if the heating rate is acceptable or if it's just too slow for you planned application or level of patience.

Used plates from a good major manufacturer like Corning, VWR, Chemglass, Buchler, even the ancient Pyro-Magnastirs, are really a better deal in many cases.
They may cost you 50 to 100% more, but they're worth it in that they have plenty of power, nice strong magnets, and all those little electronic bits inside are durable and reasonable well assembled.









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karlos³
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[*] posted on 7-6-2020 at 11:31


I've only ever bought used IKA magstirrers, and I was always lucky and happy with them.
Never paid more than like 100, maybe once even 110€, but never above.
And they are fine pieces of German engineering.

Don't shy away from getting something used is what I want to say with that.
I doubt IKA is as well available as it is in europe, but surely there are other good brands you can get used.

That reminds me, soon I have to try dumpster diving at my new uni... they are much less strict than at my last one, I guess this time I can really score something good...
A friend of mine scored at another uni on the day of ideal dumpster diving 3 still valuable magstirrers, they only cut off the cables to make them unuseable.... or rather, 5min of work each until he got three fine and well working ones, almost brand new :D
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Housane
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[*] posted on 7-6-2020 at 11:42


Thanks that is useful information SWIM,Karlos i will look into IKA magstirrers as i am in the UK




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morganbw
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[*] posted on 7-6-2020 at 11:51


I have always gone used with something that industry uses.
I presently am using a corning hotplate stirrer at ~ 600 watts, too lazy to spend a few minutes to check the actual but I am pretty sure that is close.
It gets effing hot.

Carl gave you advice on going IKA, I have never used any of these but I would trust his advise.

Do not buy new, the really good ones, cost alot.
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Housane
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[*] posted on 7-6-2020 at 12:00


yeah ebay has none, for a good price, i need it sub 100, any other website ideas?
also, i have a hotplate could i add the magnetic stirrer bit?




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morganbw
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[*] posted on 7-6-2020 at 12:12


Quote: Originally posted by Housane  
yeah ebay has none, for a good price, i need it sub 100, any other website ideas?
also, i have a hotplate could i add the magnetic stirrer bit?


I have thought about that and do not believe it is practical. You could look at the possibility of an overhead stirrer(we all eventually need one) either do it yourself or purchased.

I believe that the hotplate that I am using now was around 125 US dollars, even used the decent ones will cost a bit.
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mackolol
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[*] posted on 7-6-2020 at 12:28


I would say, don't go below 300C of max temp. As I'm using digital hotplate for some time now, I see that it is required ~100C more than compound boiling point to actually boil it due to energy loss. And the higher the boiling point is, the more temperature excess is required, because heat loss is bigger.
For example to boil water, I usually set my hotplate at 220C.

[Edited on 7-6-2020 by mackolol]
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draculic acid69
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[*] posted on 7-6-2020 at 17:50


My first mag stirrer/hotplate cost $450 and was 400watts. It couldn't boil a small pot of water.it wasn't very good so I also recommend that you don't go under 600 watts for a hotplate as it will disappoint.spend a bit more on a good one

[Edited on 8-6-2020 by draculic acid69]
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[*] posted on 12-11-2020 at 11:27


This has been gone through a few dozen times, but what are the criteria for good, credible hotplate that is capable of heating stuff up to 2-4L range?

I currently have maple scientific stirplate, and it appears to be decent for smaller stuff, but even heating ½L heat bath up to 100C takes a while, and have been taking longer recently. The stirrer motor is kind a lazy, it needs to be turned to full power to start rotating. Is it that hard/expensive to make decent plates, when there are 2000W hotplates sold for 10$ for cooking, and electric motors are literally sold by the kilo in form of computer fan that is easy to adjust the rpm?

Or should I invest into heating mantle instead? Are Chemland heating mantles w stirrer of any good? 2000mL one costs 220€ which isn't terrible at all. But 600W, is it a lot or little for 2000ml?

[Edited on 12-11-2020 by Fyndium]

[Edited on 12-11-2020 by Fyndium]
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valeg96
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[*] posted on 13-11-2020 at 08:13


Avoid anything too electronic, for the reason said multiple times so far on SM. Electronics will fry after a few years of use, and replacements are extremely expensive; less digital models (1980-1990s) are on the other hand completely repairable.




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