Sciencemadness Discussion Board

SH-2 Stirrer?

JJay - 23-10-2015 at 13:31

I am looking for a good, cheap magnetic stirrer/hotplate combo. I'd like to be able to heat 1L mixtures up to 300 C with stirring.

The SH-2 stirrer appears to have the capabilities that I want and is attractively priced. Has anyone bought one?

zed - 24-10-2015 at 16:09

300 C, is hotter than the hinges of Hell. This hot plate can achieve a surface temp of about 380.

I don't know if that is gonna be high enough, to transfer enough heat, to do what you need done.

Such adventures sometimes require a more vigorous type of heating element, along with overhead stirring, and possibly protection via an inert gas.

But, I yield to those that are more familiar with this machine.



[Edited on 25-10-2015 by zed]

ParadoxChem126 - 26-10-2015 at 06:07

I own one of these hotplates, and for many applications it can be useful. The aluminum surface heats up very fast, which is convenient for quickly heating solutions. However, for most experiments, I prefer my Corning PC-351 ceramic hotplate. The ceramic gets much hotter and has a much greater thermal mass, which gives a more stable temperature when heating. Most ceramic hotplates reach 500 degrees Celsius.

I find it extremely unlikely that the SH-2 will get you what you are looking for. As zed said, 300 degrees is extremely hot. This hotplate is not capable of heating 1 L volumes of liquid to temperatures this high. I suggest a heating mantle and overhead stirrer for your applications.

JJay - 26-10-2015 at 07:38

Quote: Originally posted by ParadoxChem126  
I own one of these hotplates, and for many applications it can be useful. The aluminum surface heats up very fast, which is convenient for quickly heating solutions. However, for most experiments, I prefer my Corning PC-351 ceramic hotplate. The ceramic gets much hotter and has a much greater thermal mass, which gives a more stable temperature when heating. Most ceramic hotplates reach 500 degrees Celsius.

I find it extremely unlikely that the SH-2 will get you what you are looking for. As zed said, 300 degrees is extremely hot. This hotplate is not capable of heating 1 L volumes of liquid to temperatures this high. I suggest a heating mantle and overhead stirrer for your applications.


I had a Fisher Thermix ceramic a while back that I liked a lot... it could easily heat oil baths to 300 C.... Corning makes high quality equipment too. So perhaps I should pick up a used ceramic hotplate, Fisher or Corning.

I have used heating mantles before, but I like the ability to use any size flask... I have not used overhead stirring... at high temperatures what is the advantage of overhead stirring over magnetic stirring?

ParadoxChem126 - 26-10-2015 at 08:30

Heating mantles do not usually come equipped with an integrated magnetic stirrer, so overhead stirring is needed. Overhead stirring is also advisable because heating such a large volume of liquid to such a high temperature requires strong mixing to provide even heat distribution. Overhead stirrers are inherently more powerful than magnetic stirrers.

May I ask for what reason you need such serious heating? Keep in mind that traditional glassware can be considerably weakened at such high temperatures.

JJay - 26-10-2015 at 09:21

I don't have a specific purpose in mind for really strong heating, but I recall using high temperatures at high vacuum to distill high-boiling substances when I wanted to prepare high purity products from technical grade reagents, especially when I suspected dangerous contaminants, even in tiny quantities. Usually I used oil baths, but I have used sand baths too. It's very true that high temperatures weaken glassware... I've seen a lot of boiling flasks break at high temperature... probably a good idea to use quartz.

Right now I have a couple of thrift store electric drills and a PTFE stir paddle and bearing... I wonder how the drill motors will hold up under continuous duty....

JJay - 26-10-2015 at 13:12

Quote: Originally posted by ParadoxChem126  
Heating mantles do not usually come equipped with an integrated magnetic stirrer, so overhead stirring is needed. Overhead stirring is also advisable because heating such a large volume of liquid to such a high temperature requires strong mixing to provide even heat distribution. Overhead stirrers are inherently more powerful than magnetic stirrers.

May I ask for what reason you need such serious heating? Keep in mind that traditional glassware can be considerably weakened at such high temperatures.


Oh and FYI it is possible to use a non-heating magnetic stirrer with a heating mantle - you simply place the mantle on the stirrer.