Croc-Pot flask bath

[PYRO500]

Recently I was visiting a local store, I was looking for things to add to my lab such as equipment and chems, I have been having trouble keeping my flask at stable tempature beacuse my propane burners heat the pan with sand too fast. What I am proposing is to use a croc-pot witch is like a big bowl that will cook food, now I know these things get at least 100F beacuse they will boil away water (albiet slowly due to evaporation cooling). I was wondering how hot these things could get, and if you could say, fill them with sand (after removing the inner bowl for better heat transfer) and bury a distillation flask in one, this would allow for the flask to get slowly heated and a homemade thermostat could be easily implemented. If anyone has anything to say please post, I think if it will work it would make a very useful addition not only to my lab but possibly several others. the reason I am considering this is that they no longer sell hotplates anywhere (well where I shop) beacuse they are notorious for idiots starting fires, now lab grade hot plates are expensive but a croc-pot type cooker is very cheap the generic ones run at less than 20 dollars and are perfect for heating round flasks buried in sand/oil bath.

[J]

Do you mean the small (~12 inches diam, 10 high)round cookers used for making stew?

J

[nbk2000]

A croc-pot would be great if it can keep a precise enough temperature. You might have to make up a thermostatic controller yourself to turn it off and on at a set temperature since I don't thing the built in on is going to be able to maintain it within a few degrees.

I'd use oil instead of sand for the croc-pot. Much more even heating, easier to get the flask in or out, and you can see what's going on in it too.

You may want to make a lid for it so the neck of the flask can poke out, but otherwise it's covered. Prevents heat loss.

[Mick]

well, if you can make a thermostatic controller, then why not buy a stove element, and make a stand for it then hook the controller up to that.(basicly, it would be like making your own portable stove)

or possibly what would easier would be to go to the waste dump, and find and old oven with a stove top, and remove the stove top(this is a ssuming that waste dumps in your area allow the dumping of old stoves and what not)

the reason i say this is because i don't think crock pots get all that hot (i have one, and it only goes up to a simmering temperature)

[CyclonitePyro]

<a href="http://www.sciplus.com" target="_blank">www.sciplus.com</a> sells heating elements and a few other cool things pretty cheap.

[Agent Blak]

I would have to agree that a oil or shortning bath would work better than sand. I read about a guy using a oil Bath to melt KNO3/Sucrose for Rocket engines and so on. just be careful when working around hot(350+) oil if water get in there it can flash boil it. Boils over and get grease everywhere. But it is a very good Idea.

[CommonScientist]

I smell a fire hazzard here! Wouldnt the oil catchon fire? Has anyone heard of a grease fire? It would all depend on your type of oil I guess, Saftey First.

I agree with NBK that you need a lid so that you dont loose heat from it. Home Depot might sell osme reflective sheeting, its like paper, white on one side, resflective on the other. Its great for insulating things. You could get a piece of plywood, cut a hole in it for the neck of the flask. Get sheet styrofoam and cut it to fit the bottom of your lid, then glue the reflective sheeting on the bottom to aid in insulating. This should work fairly well.


YAY! - Im a Bottle Washer! :)

[FragmentedSanity]

Most crock posts come with a lid, usualy glass or ceramic - I think you would want to make your lid out of wither of those materials - or modify the original so as to accomadate your flask; rather than using foam or something similar - insulating layer or not its still likley to overheat.
An idea similar to this is to use an old deep fryer - they get hotter, and come with avariable thermostat, which my or may not be up to your task. The best part is that with everybody getting all health conciious these days its easy to gome across a cheap secondhand deep fryer.
Ive also heard of crock pots being used as a refluxing chamber - the lid is inverted and filled with ice - so the stuff inside the pot condenses and drips back down off the center of the lid.

[CommonScientist]

Quote form FragmentedSanity:

"Ive also heard of crock pots being used as a refluxing chamber - the lid is inverted and filled with ice - so the stuff inside the pot condenses and drips back down off the center of the lid."
Why would you want to do that? I thought that we were trying to distill something?

Anouther quote form FragmentedSanity:
"The best part is that with everybody getting all health conciious these days its easy to gome across a cheap secondhand deep fryer."

Over here in the US of A, everyoe is becomeing slobs and obese whales, well osme of them. I owuld just go down soem streets on trash day and find something that you like, I did that once and I found a sweet fan, that I still use today - point being, you never know when you will find something.

[FragmentedSanity]

We were talking about the use of crock pots for improvised lab equipment - I was just pointing out another way you can utilise them. Lots of things need refluxing - its an especially good way of doing solvent extractions for larger amounts of materials - plant matter for example. CommonScientist - if you dont like the idea you can just ignore it, but some people like to use their equipment for as many different things as possibe - or would be more inclined to aquire an apparatus that they could use for more than one application. Also, if you would rather walk the streets on trash day untill you find a working example of the device your after, rather than spending a couple of bucks at a secondhand shop or a garage sale - Go right ahead; personally I have better things to spend my time on.

[CommonScientist]

Im not putting anything against you, as you are probly more intelligent than me(in certain areas). I dont walk the streets to find crap, it would be a waist of time, I was just posting a method of finding stuff. No offense was ment. We are all here to provide information, which I am trying to do. I am not very fond of refluxing, what is it?

I try to improvise as much as possible. As most people do to get the best out of their equipment.

I spend my spare time on this website, studying it, learning as much as I possible can, while also providing information to other members. I am just trying to help. Bear in mind that I am deprived in labware, so you can imagine how much I try to improvise.

[Skean Dhu]

You want something similar to an electric frying pan. looks like a skillet on legs and there should be some sort of connectiong that a thermostat goes into. the thermostat is on the end of an electric cord which can be removed and has a dial that goes up to like 300-400*F in 25* increments. more or less what your looking for, http://www.kitchenshop.com/catalog/IL-31101.shtml. your best bets are 2nd hand stores, and garage/yard/rummage sales, I'd go to the garage sales personally because you can negotiate prices

[tom haggen]

I don't think a grease fire would be that big of an issue. Flash boiling on the other hand can be very dangerous. If you dropped enough water in a vat of oil that is 350F your looking at one hell of an eruption. This type of an eruption can lead to a serious grease fire, especially if your using a propane burner to heat your oil. When all else fails keep some sodium bicarbonate handy, and deep fry your turkeys outside on the concrete.

[Spoz]

I have been very successful with the oil bath method, used to melt just a KNO3/sucrose mixture. You would have to be doing something dumb to let water fall into the pot though... the main advantage is that its very even heating and can be controlled fairly accurately - I used a propane burner as it was only small amounts of KNO3/sucrose. It also has a good temp range - I used to use mine at around 150C but they can go past 200.