Sciencemadness Discussion Board - Hotplates!

Hotplates!

Rich_Insane - 6-5-2012 at 13:19

Hey guys. So I've decided to get a new hotplate. I'm a bit confused on what I should get. I can't afford those really nice mag stir/lab hotplates, so I've settled on this: Aroma Hotplate

Is it a good decision? Are there similarly priced options?

kristofvagyok - 6-5-2012 at 13:31

Quote: Originally posted by Rich_Insane

Hey guys. So I've decided to get a new hotplate. I'm a bit confused on what I should get. I can't afford those really nice mag stir/lab hotplates, so I've settled on this: Aroma Hotplate

Is it a good decision? Are there similarly priced options?

It's cheap, it should heat, it is simple, it also has 1 year warranty. Get it and use it.

But a new topic for this?

eBay!

sargent1015 - 6-5-2012 at 13:36

Personally I'd wait for something to pop up on eBay. I bought my stirrer/hotplate for 40 bucks and it is terrific!

It is a Markinson.

If you want to get that one for now, just to have something, go for it. But, keep your eyes peeled for a really nice one!

Endimion17 - 6-5-2012 at 14:13

Have you ever bought really small hotplates like this one?
They're rarely above 500 W, but do their job perfectly. Energy efficient and space saving, they usually cost less than 25$. This one has an 80 mm diameter plate. It's great for distillations and hotbaths as it doesn't heat up anything else besides the beaker/flask.

bbartlog - 6-5-2012 at 14:43

Neat item, Endimion. I'll have to get one of those at some point. Of course it doesn't have magnetic stirring and probably can't melt zinc, but 75% of the time it would get the job done.

Endimion17 - 6-5-2012 at 15:32

Given the price of ~22$, it's perfectly fine, although I'd prefer a potentiometer over a 0/I/II button (225 and 450 W) to fine tune the heating.
I doubt it could even melt lead in an insulated iron vessel because its melting point is close to the point where the safety system shuts it down to prevent overheating damage.
Being so small, it heats up the needed object only. One of the things I really hate is when I have to heat up a small beaker using a large plate. The rays are killing my fingertips.

Rich_Insane - 7-5-2012 at 13:22

Hey guys, so I have a quick and slightly related question. I'm at maximum budget, and have to cut out the paraffin oil from my purchase. For an oil bath that needs to reach 120oC, will canola oil be OK? I have several gallons of canola oil, so it would be cheaper for me. Is it a hazard of any sort?

sargent1015 - 7-5-2012 at 17:09

Quote: Originally posted by Rich_Insane

Hey guys, so I have a quick and slightly related question. I'm at maximum budget, and have to cut out the paraffin oil from my purchase. For an oil bath that needs to reach 120oC, will canola oil be OK? I have several gallons of canola oil, so it would be cheaper for me. Is it a hazard of any sort?

It'll smell like you are deep frying stuff

So if that's a good smell for you, I don't see why not

Or you can buy mineral oil (hypoallergenic baby oil)

Fossil - 7-5-2012 at 17:45

Vegetable oil also works decently for oil baths, although if you have some money to spend, get these. http://www.labarmor.com/lab-armor-beads-for-lab-water-baths/

I have some and love them, super convenient, no need for cleaning your glassware of oil, and they go over 500C if i recall correctly. Really a great investment if you are able to shell out the money.

reincarn - 7-5-2012 at 18:19

For high temp stuff I am thinking of using candle wax.
They are normally paraffin wax (not oil) and I have a box of left-overs.

Bad idea?

sargent1015 - 7-5-2012 at 20:45

Quote: Originally posted by reincarn

For high temp stuff I am thinking of using candle wax.
They are normally paraffin wax (not oil) and I have a box of left-overs.

Bad idea?

I'm pretty sure that's not a great idea, owing only to the fact that it would be a MESS to clean up. I don't like wax in general..

Plus, mineral oil (paraffin oil) is CHEAP! If you don't want to pick it up at your local pharmacy, check out eBay.

$15: http://www.ebay.com/itm/MINERAL-OIL-1-GALLON-/140489295317?p...

By the way, @Fossil, that bead bath is awesome! I may have to invest in one of them...

[Edited on 8-5-2012 by sargent1015]

Funkerman23 - 7-5-2012 at 21:12

Hey Fossil! they sell to individuals?

Fossil - 8-5-2012 at 04:07

Yes they do, they even give out free samples, to home chemists like us! I highly recommend you check them out as they are very friendly and offer an extremely good product.

GreenD - 8-5-2012 at 04:26

I have a miniature hot plate / stir plate you can have for 50$.
probably 3x3'' top. Heats up to 250mL easy.

Dr.Bob - 8-5-2012 at 07:24

If you use vegetable oil in a heating bath, especially canola oil, it will go rancid before long and smell bad as well as polymerize. Mineral oil, fully saturated vegetable oil (coconut or palm are OK), and even motor oil are all OK, but many veggie ones will oxidize over time and get nasty.

I haven't tried the beads, although they look great, I may try them out. I use sand, oil and dry Al heating blocks for heating baths.

Rich_Insane - 8-5-2012 at 12:25

Quote:

If you use vegetable oil in a heating bath, especially canola oil, it will go rancid before long and smell bad as well as polymerize. Mineral oil, fully saturated vegetable oil (coconut or palm are OK), and even motor oil are all OK, but many veggie ones will oxidize over time and get nasty.

Will it go bad after maybe 3-5 hours at 100-150oC? I was thinking of heating some oil for the bath, doing my reaction then dumping the oil (wash the bath dish afterwards).

Hexavalent - 8-5-2012 at 12:40

I have used saturated vegetable oil previously to heat reactions to at least 200*C. I must have heated and cooled my current batch of oil maybe 10 times, and yet nothing has happened to it. When/if something does happen, its very cheap to replace and I would recommend it for heating baths, based on my experiences with it.

Personally, I also quite like air and water baths, but I detest sand baths. They are slow to heat, as sand is actually a poor thermal conductor, messy, and take for ever to get up to the desired temperature and are really slow to cool as well. I have also heard of people putting sand baths in the oven before placing on the hotplate, to heat them up slightly, but if I can I always try and leave very hot things where they are until they've cooled.

IIRC, I think a member of this forum once melted the top of their hotplate due to sand baths causing massive thermal insulation.

sargent1015 - 8-5-2012 at 12:41

Quote: Originally posted by Rich_Insane

Will it go bad after maybe 3-5 hours at 100-150oC? I was thinking of heating some oil for the bath, doing my reaction then dumping the oil (wash the bath dish afterwards).

Seems like such a waste....

Hexavalent - 8-5-2012 at 12:52

Not really, I would rather replace it than keep rancid oil. You can get veggie oils of all kinds very very cheaply from many wholesalers that sell to the public . . .failing that, go to the supermarket and get some there. Where I live, I can get 2.5L for just under £3.

sargent1015 - 8-5-2012 at 12:55

I agree with after it gets rancid due to multiple use, but for a one time use and dump?

EssOilChem - 8-5-2012 at 18:16

Quote: Originally posted by Fossil

Vegetable oil also works decently for oil baths, although if you have some money to spend, get these. http://www.labarmor.com/lab-armor-beads-for-lab-water-baths/

I have some and love them, super convenient, no need for cleaning your glassware of oil, and they go over 500C if i recall correctly. Really a great investment if you are able to shell out the money.

I had a thread on that here, but someone told me that they aren't rated to be that hot. There are some alternatives mentioned in the thread also.
The tech specs on their website confirmed that (-180C - 180C), however real life application may be different I guess.

grndpndr - 8-5-2012 at 20:00

I bought a simple 1100watt single burner by guess and by god temp control HP on sale at the local A+e hdwr for around $15.Its been working fine for a yr now it just takes care not to overdo heat.Ive seen to many stove fires via cooking oil to feel safe around an oil bath.Ive used sand baths and they are slow to heat(not to bad with 1100watts) if your simply distilling HNO3.It also worrys me if my glassware should break dumping the contents of a nitration or distillation(HNO3).Unfounded concerns say with mineral oil?Im also considering copper coated steel BBs?

This may be a stupid idea(not my first) but has anyone tried or considered the use of the cheap unscented clay based kittly litter similar to whats used to absorb oil spills from garage floors?LOL?

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

Rich_Insane - 9-5-2012 at 20:52

I think anything with low flammability, low specific heat and low volatility will do... I'm just worried that cooking oil can catch on fire -- although I don't plan on going above 120-150oC.

Fossil - 10-5-2012 at 03:56

Quote: Originally posted by grndpndr

I bought a simple 1100watt single burner by guess and by god temp control HP on sale at the local A+e hdwr for around $15.Its been working fine for a yr now it just takes care not to overdo heat.Ive seen to many stove fires via cooking oil to feel safe around an oil bath.Ive used sand baths and they are slow to heat(not to bad with 1100watts) if your simply distilling HNO3.It also worrys me if my glassware should break dumping the contents of a nitration or distillation(HNO3).Unfounded concerns say with mineral oil?Im also considering copper coated steel BBs?

This may be a stupid idea(not my first) but has anyone tried or considered the use of the cheap unscented clay based kittly litter similar to whats used to absorb oil spills from garage floors?LOL?

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

[Edited on 9-5-2012 by grndpndr]

Its is unlikely that the clay would harden the same as if it were in a kiln, but the clay still might harden since it will be heated, therefore the moisture escaping from it.

[Edited on 2012-5-10 by Fossil]

grndpndr - 12-5-2012 at 15:29

I see your point and the consoderation of the caly hardening slightly due to moisture loss.I would think it would have to contain quite a bit of moisture but to be sure the 'clay' if prheated to lose the moisture should obviate
that problem.Clever concern tho seems to me,thanks!

grndpndr - 14-5-2012 at 11:10

Ill try to Be Sure I dont use 'wet' absorbent litter as well!

Hexavalent - 14-5-2012 at 12:22

I like your idea grndpndr, but I can only attest to what the others have said.

Personally, I would like to report experimental success with the air bath technique, and I hope to acquire some copper BBs soon to try that technique.

@grndpndr - On a side note, not to sound moderator-ish, if you need to add something to what you've said, then please use the edit feature when possible and practical. Posting multiple times sequentially only to add further detail again and again only serves to bolster your post count.

Mailinmypocket - 26-7-2014 at 09:52

Quote: Originally posted by Fossil

Reviving this old thread because labarmour gives a free sample of lab bath beads. I had to pay 10$ for a sample because I am not in the USA but still worth it! The sample is a nice size for doing small scale stuff, they work nicely.

Texium - 28-7-2014 at 07:09

Quote: Originally posted by Rich_Insane

Haha, that's the exact hotplate I have. It kinda sucks, but it does the job. Heating is erratic and uncontrollable though. It seems that the low setting will get just as hot as the high setting, it just takes a whole lot longer to get there.

gregxy - 28-7-2014 at 09:58

One thing to check is if the thermostat is electronic or electro-mechanical. Electro-mechanical meaning there is a switch that turns on and off when it reaches temperature.
Such a switch could ignite flammable vapors.

MrHomeScientist - 28-7-2014 at 11:18

Quote: Originally posted by Mailinmypocket

Looking at their free sample page, though, it states "This offer is only available for shipment to U.S commercial addresses." That limitation would put this offer outside the grasp of most members here. Does that not also apply to international orders?

Loptr - 28-7-2014 at 11:44

Quote: Originally posted by Mailinmypocket

Quote: Originally posted by Fossil

I just used my work's office address with it addressed to me.

Mailinmypocket - 28-7-2014 at 13:07

I used my home address and bullshitted a company name. Worked. I don't think they run this through a system like they do chemical orders. Just invent a name and go with it. It's metal beads afterall, no harm there.

[Edited on 28-7-2014 by Mailinmypocket]

Dr.Arz - 1-11-2014 at 07:24

Im thinking now what bath material I will use. Paraffin wax is cheap and it has good thermal capacity and it's supposed to be stable at high temperatures. I will need heating bath with 130C capacity at normal but with one exception that needs to go up to 180C.

Sand baths are known to kill hotplates because they act as insulators so it is not an option.

What could be best:

- paraffin wax
- paraffin oil (whats the difference actually?)
- silicon oil
- 5.1 brake fluid
- steel shot

DrMario - 1-11-2014 at 07:35

Quote: Originally posted by Dr.Arz

- paraffin wax
- paraffin oil (whats the difference actually?)

Average number of carbon atoms in aliphatic molecules. Obviously, oil has shorter aliphatic chains than wax.

Sometimes it's clearer when you call paraffin oil as "mineral oil". But then some call it petroleum ether and things are all f###ed up again.

DrMario - 1-11-2014 at 07:42

Maybe I'm going to say something outrageous, but isn't Galinstan the ideal bath liquid - apart from the very high price? It ha a sub-zero melting point, a boiling point of 1300C, very high thermal conductivity and a very low vapour pressure.

What's not to like (apart from the high price, as mentioned)?

Dr.Arz - 1-11-2014 at 08:16

Am I getting pissed off again, or am I just expecting too much from my hotplate? I heated up at full power about 500ml of water in a beaker to test it out and never got it boiling, hottest it got from about half an hour is 85C. Meanwhile I got bored and put up my gas cartridge range heater with half a liter of water and it came up from RT to boil under 5 minutes. Hotplate is rated at 500W and the gas heater is approx 2kw.

If these plates are so shitty I've got to get the overhead vac stirrer going asap...

Dr.Bob - 1-11-2014 at 11:12

500 watts is not a lot. The Corning stirring hotplates PC-320 are 575 watt, and that is just enough to do some real heating, but they take a while to heat up. I think if you want to heat water to boiling, you will need at least 1000 watts of heating power. Some of the larger hotplates do that. But few labs boil water in a beaker, so the basic hotplates are mostly designed for heating smaller organic reactions, which takes less energy than boiling water.

Dr.Arz - 1-11-2014 at 12:23

I need to do distillations (mostly sub 100C boiling solvents in ntp) and then vacuuming with reagents from 100 to nearly 300C. In vacuum stirring or bleeding is absolutely necessary otherwise it will bump and puke all up. I bougth new plate to do this but it seems too unpowerful. Some distillations may be much larger in volume so it seems i need my gas heater after all.

Argentum - 7-6-2015 at 13:58

Short question, which doesn't deserves a separate thread. I need some help with choosing a hotplate stirrer.
I've got two choices: Bante ms400, 400º and 2l of stirring capacity, its a good choice if you look at the price, but I couldn't find any "review", just one video on YouTube which promotes it and another one which says is a piece of s...
The other choice is a Numak (the seller wouldn't tell me the model) which can reach up to 300º and stir 10l. I couldn't found any information on the iInternet unfortunately, not even the brand!
Does anybody have any experience with these brands?
Oh, this are the only two hotplates I can buy with my budget, and I can't bring nothing from other countries because I live in the nether regions of the underworld