Author Topic: Which hotplate/stirrer?  (Read 2069 times)

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demorol

  • Guest
Which hotplate/stirrer?
« on: February 01, 2002, 08:47:00 PM »
My old hotplate/stirrer is not powerful enough to stir larger quantities of liquid or solutions with high viscosity. now I have decided to buy another, larger one. I've already checked labx, but there seem to be only those made to plug into 120V plug. then I visited the websites of two the most known hotplate/stirrer manufacturers: T******yne and C****ng. Here are short descriptions of two of the models I'm interested in the most.

C*****g
Plate size: 10×10", chemical and scratch resistant top
Stir range: 60-1100 rpm
Heating range: 25-550°C


T******yne
Plate size: 12×12", impact and chemical resistant Cimarec top
Stir range: 100-1000 rpm
Heating range: to 538° C

As I said before, these two are the most wanted, but I've found another one. Here's a description:

Bi**y hotplate/stirrer, HC 1202
Plate size: 290×290 mm
Stir range:0-1300 rpm
Heater power:1250 W (450° C max.)

Please help me with some suggestions, because I don't want to spend money on a hotplate/stirrer that is not worth its name. I know T******yne and C*****g  are both very good, but what do you think about the third one.
Life without chemistry would be a mistake.

sYnThOmAtIc

  • Guest
Re: Which hotplate/stirrer?
« Reply #1 on: February 02, 2002, 05:03:00 AM »
Well if its volume and viscosity you want to push then usually the larger the plate size the more it can move(helps to just know the hp). I'd say the thermo 12x12 would move more volume. I mean it is only logical. You'd be quicker to sit 20l drum on a stool than a mason jar right?

If it has a large impact resistant surface it is more likely to stir large ammounts than a smaller one. Though the failure is usually not in the motor of the stirrer or the size its the magentic attraction between the base magnet and stirbar.

 Like pinky finally got an overhead cause 100g of al amalgum couldn't be stirred even with a 500 buck 55gal mag stir cause the magnet would just keep flipping off cause the fluid was so thick the magentic attraction was too weak to keep them attached. He modified a 6x6 with a 120v dc electromagent as the base mag and not is stirs 20l of sludge no prob.

If you look for milling heads that are sealed to prevent fouling up with metal or wood or cooling fluid then it won't matter if it is sparkless or not cause the workings are selaed form any work-piece contaminants. They are sold for mounting above lathes or small milling tables for about a 100-200 bucks and the 1/5hp has turned anything put to it so far with no prob. If you'd like a pic for reference then I'll finally break down and take some pics.

PoohBear4Ever

  • Guest
Re: Which hotplate/stirrer?
« Reply #2 on: February 02, 2002, 07:50:00 AM »
What's a good overhead stirrer for, say, a 2-3x MM Al/Hg?

PB

sYnThOmAtIc

  • Guest
Re: Which hotplate/stirrer?
« Reply #3 on: February 02, 2002, 09:55:00 AM »
A flex shaft off a dremel will work fine for that scale. HEll a drill and paint mixing paddle will work great in the baal bucket procedure. Or if looking for a real stirrer at least 1/8hp motor with low rpm and constant torque.

PoohBear4Ever

  • Guest
Re: Which hotplate/stirrer?
« Reply #4 on: February 02, 2002, 10:30:00 AM »
I recall a thread about that now that you've mentioned it.  SWIP would also like the ability to stir the 10L oxone solution as well, at 1800rpm... 

Thanks for the tips, now I just gotta locate a paddle,

PB

RoundBottom

  • Guest
Re: Which hotplate/stirrer?
« Reply #5 on: February 02, 2002, 08:16:00 PM »
SWIM is still using a 3" octagonal stirbar for 2x MMs.  it can be difficult to get the foil stirring, but usually once it's going it doesn't stop.  anecdotal evidence says that the smaller the foil nuggets, the less the drag in the MeOH, the easier to stir.

i learned a thing or two from charlie dontcha know.

PoohBear4Ever

  • Guest
Re: Which hotplate/stirrer?
« Reply #6 on: February 02, 2002, 10:40:00 PM »
The problem is, though, that SWIP has discovered that his stirrer is a complete piece of shit, so all he can use is the hotplate from this combo...

Then again, he has thought about buying new, and wonders if a Corning 620 might solve the problems he's encountered...?

PB


blaztoff

  • Guest
Re: Which hotplate/stirrer?
« Reply #7 on: February 02, 2002, 11:06:00 PM »
Swim has had several Corning stirrers. The 420-620 are all right. But niether is designed to stir more than 1L of liquid. Check the manufacture listed capacity for stirrers before you buy one. The cool thing about the new corning stirrers is they have a load sensor that tells when viscocity changes but they suck for amalgams. The 420-620 barelly are adequate for the written AL/hg 25g reaction. Anything more does not work. And bigger top plate i.e. the 620 10x10 does not mean stronger stirring. Same magnet just bigger surface area.
Swim can improve stirrer performance by using a rare earth magnet stirbar. Search and a few companies offer them about 30-50 us dollars. Also do a search under say the thomas regional and find a company that has rare earth magnets and see about replacing the existing magnet with one preferabbly a somarium-cobalt one. Now thats stirring power.
Looking for a good stirrer combo. Suggest looking at stirrers made by IKA. Those fuckers rock and if you can afford it go digital. Much better control awesome. Also IKA makes a digital oil water bath with magnetic stirring. Now thats thing SWIM likes.

demorol

  • Guest
Re: Which hotplate/stirrer?
« Reply #8 on: February 03, 2002, 07:26:00 PM »
Let me ask you this way, which hotplate/stirrer are you using for MM Al/Hg + nitromethane?
Life without chemistry would be a mistake.

blaztoff

  • Guest
Re: Which hotplate/stirrer?
« Reply #9 on: February 03, 2002, 08:40:00 PM »
For a large Al/HG use overhead stirring. But for most you can get away with quite a few. Actiually the Th***mo***ne No**va is actually a pretty good stirrer for a cheap price. The manufacturer rates it to stir I believe was 20L not bad. But if you get a rare earth stirbar thatv alone will be able dramatically increase youre stirring capacity. It has way more coupling power and will not get stuck or spinout. And later replace the stirrer magnet ofr even better power. Thats what the high capacity stirrers use-a rare earth magnet.

RoundBottom

  • Guest
Re: Which hotplate/stirrer?
« Reply #10 on: February 03, 2002, 09:23:00 PM »
SWIM????  th*****yne 1000, the big boxy type.  7"x7" Al top.  heating is forked on it, doesn't get above 100°C... that's why SWIM uses mantles.

i learned a thing or two from charlie dontcha know.

blaztoff

  • Guest
Re: Which hotplate/stirrer?
« Reply #11 on: February 04, 2002, 01:58:00 AM »
NO not that one. The The** something but the other model. Mantles can be dangerous. Swim recentlly had one catch fire on him when hr turned his back for 5 minutes. Swim likes the IKA magnetic Stirbath. Temp to 400C 4L capacity for the oil bath. Stirs 20L and usses fuzzy logic so you just program the temp + stirrng and it will automatically sense it and achieve desired temp. No waiting for heat transfer from plate to pot to flask. Use it for a stirrer too. And you can program it for a temp ramp.