Sciencemadness Discussion Board

DIY magnetic stirrer from fan and neodymium magnets

alchemizt - 8-12-2021 at 16:36

I'm going to build this magnetic stirrer:
https://youtu.be/ZVYK2lhZq9U

What I'm not sure about is whether a 12V computer fan will be powerful enough. Would it be powerful enough to stir up to 10L of liquid? I could probably use the same curcuit with a house fan that qould be a lot more powerful.

crow6283 - 8-12-2021 at 17:09

Hell to the no it won’t be powerful enough. Even a lot of very nice very expensive magnetic stirrers can’t stir 10 liters.

j_sum1 - 8-12-2021 at 17:38

I have a couple of these. They are quite useful if I ever need to dissolve several things at once in the 250mL range. It is quite a nice idea and costs nearly nothing. Worth it IMO. But not for 10L. For that I would be buying a paint stirrer and a dedicated drill.

alchemizt - 8-12-2021 at 18:19

Ah so the capacity of a 12V fan motor is about 250ml? It wouldnt stir say 1L? For 1L would I need to step it up to a 48V DC fan?

alchemizt - 8-12-2021 at 19:07

I came across this video:
https://youtu.be/rGhSZwOf6sE
Where he makes a 5 gallon magnetic stirrer using a DC fan

crow6283 - 8-12-2021 at 19:49

What you are trying to stir is going to be a factor to, and how you operate it. If you are say, stirring water and start the stirrer with a small amount in the flask and add more you can stir quite a bit more than you can with all that water in the flask and no stirring. Size and shape of stir bar relative to the size and shape of flask and what you are stirring also plays a big factor . Actually running a reaction with sketchy stirring conditions can be a real risk though, what are you gonna do if the thing stops stirring mid run and you can’t get it started again? Something to think about. Always best to have an excess of stirring power and not have to use it all then to push the envelope.

Sulaiman - 8-12-2021 at 23:56

@ j_sum1 : do the fan blades have a function or would it be better to cut them off?