Sciencemadness Discussion Board

Using a small deep fryer as an oil bath

diggafromdover - 11-1-2016 at 20:09

It has occurred to me that a Fry Daddy or the like, filled with DOT 5 Brake fluid, would make a serviceable oil bath. Has anybody tried such a thing? I would be interested in hearing. A silver mark to the best reply!

Detonationology - 11-1-2016 at 20:26

'Koma! Someone wants to know more about your setup...

How to make an oil bath ???
FIRE!!!!! A Warning

violet sin - 11-1-2016 at 21:33

I have one also. Works great. Even comes with a lid for when not in use. Has the breakaway power cord, held on with magnets too. So you don't move it and come to a dead end on the cord, trying to wear all the hot oil down your front :P

Not the most professional, but no problems with it. If you get one used from a thrift store and.It doesn't heat, could be a thermo fuse blown. Easy to fix, cheap part.

Also, I use mineral oil in mine. In case of a broken flask,.. be wary. Hot oil + water = LAME! So exercise caution in places like a basement, confined/cluttered lab space or near stuff prone to combustion.

[Edited on 12-1-2016 by violet sin]

bobm4360 - 11-1-2016 at 22:43

As most fry cookers are regulated for cooking french fries and the like, an appropriately rated Variac will help when the bath doesn't need to be that hot.

Regards, Bob

violet sin - 11-1-2016 at 23:09

Modified cheap ebay rex-c100 pid. --> ssr (included with pid) --> remodel box and outlet from ace hardware

Plug in the deep fryer to the pid controlled outlet. Might cost ya 30$. Just don't let the probe pop out of the oil. Full burner for a while *will* blow out the thermofuse if not worse. As it is full on trying get the probe up to temp. Lost one fuse that way, had to hardwired it on bypassing the blown fuse, and continue what I was doing. Replaced it afterward though. My mistake was too little oil for a small job, didn't cover the tip... I was right there so I saw it trying to self destruct. But if you bypass that little gem, it won't cut out, and will cause major problems.

Bert - 12-1-2016 at 07:26

Done that. Prefered to use it as a sand bath, no oil spills or fires. Scratched up my glass though.

Now occasionally using one as an Aluminum shot bath.

Yes on the PID. Got a couple of different probes for various uses.

careysub - 12-1-2016 at 07:39

Quote: Originally posted by Bert  
Done that. Prefered to use it as a sand bath, no oil spills or fires. Scratched up my glass though.


I suggest people give calcium carbonate sand a try, if a sand bath they must have. Much softer than silica (Mohs 3 vs 7).

It is sold as "play sand" at many home centers (preferred to silica for children, apparently) and also for aquariums and reptile enclosures. What do all of these uses have in common? The critters eat the sand.

Aluminum is far superior though.

blogfast25 - 12-1-2016 at 07:47

I use one too. No problems at all.

chemrox - 12-1-2016 at 15:57

I have a deep fat fryer I use with N-dibutyl pthalate as the oil. This system gets me to ~ 300*C without smoke. This is *not* a substitute for an appropriately sized mantle but for reax where even heating and temperature control are critical it works almost perfectly. Temps are within +/- 2*C. Brake fluid was inferior; smoking at above ~ 225*C. Silicon based oils are without par but super expensive. I ran into the pthalates searching for a glassware type manostat (Vogel's 3) oil. Finding a deep fat fryer with good temp control is the only real challenge. Sand baths can be OK but the temperature control is harder to manage. I ran a mega soxhlet with a sand bath and hot plate. I used a temperature controller that operated the on/off on the hot plate. It took almost an hour to set the base temperature on the hot plate so as to avoid constant switching. I used the sand bath because the flask was too big for the oil bath. I really appreciate the even heating and temp control I get from the deep fat fryer but in general I much prefer good heating mantles. Sand baths are notorious for scratching glassware. They are best used with Cu retorts.

arkoma - 12-1-2016 at 16:07

Quote: Originally posted by Detonationology  
'Koma! Someone wants to know more about your setup...

How to make an oil bath ???
FIRE!!!!! A Warning


LOL.

careysub - 13-1-2016 at 12:50

I just looked at a Presto ProFry in the store, price is about $45 and it takes 8 cups of oil. It has a temperature control dial going up to 190 C (375 F). That should handle many use cases.

The Volatile Chemist - 13-1-2016 at 14:28

I don't suppose Crock-Pots work well as heating baths, do they? Probably not hot enough. Our local grocery store is selling a dip-size one for $10 (!) and a larger one for $20.

Bert - 13-1-2016 at 14:36

The dip size one takes forever to heat up, and do not get very hot in my experience. Ended up using them for something else.

The bigger ones are variable in performance, but all are slow to heat and slow to cool if the ceramic liner is in place.

careysub - 13-1-2016 at 14:57

Quote: Originally posted by The Volatile Chemist  
I don't suppose Crock-Pots work well as heating baths, do they? Probably not hot enough. Our local grocery store is selling a dip-size one for $10 (!) and a larger one for $20.


No, definitely not hot enough. Most have a peak heating capacity around 250 watts.

diggafromdover - 14-1-2016 at 06:49

It's tie. I judge that chemrox and violet sin had the most useful posts. U2U mailing address for a half mark each.


[Edited on 14-1-2016 by diggafromdover]

The Volatile Chemist - 20-1-2016 at 16:30

Quote: Originally posted by Bert  
The dip size one takes forever to heat up, and do not get very hot in my experience. Ended up using them for something else.

The bigger ones are variable in performance, but all are slow to heat and slow to cool if the ceramic liner is in place.

OK, makes sense. Then what about without the liner, would it be similar to a normal mantle, but without the 'mantle' part? Perhaps it is just best to stick with a normal bath in my new 1L beaker (thanks mom :))

Funkerman23 - 21-1-2016 at 22:12

I've seen the Presto fryer electric pots here and there but never actually tried to use one lab wise. Sure tempting though, given the scarcity of affordable stir mantles.. I'm still searching for the odorless heating fluid though, havent found it yet. I'll also check out the arkoma links but at this rate I think a soft mantle on top of my corning hotplate stirrer would work better... my whining aside, look around for wiser hands than mine. I lurk as of late.

JJay - 21-1-2016 at 22:15

Soybean oil is not bad as a heating oil. It's not completely odorless, but it doesn't smell much and is nontoxic. Paraffin wax is almost odorless but is a pain to clean off of the glassware and is a solid at room temperature.

Funkerman23 - 21-1-2016 at 22:30

Quote: Originally posted by JJay  
Soybean oil is not bad as a heating oil. It's not completely odorless, but it doesn't smell much and is nontoxic. Paraffin wax is almost odorless but is a pain to clean off of the glassware and is a solid at room temperature.
I haven't tried the paraffin wax yet but I can tell you mineral oil stinks like hot crayons when used! It worked but after two tries the stuff formed a yellow tinge to it.Since I didn't need to add ore stink to the room and I am not familiar with its breakdown behavior I decided to look elsewhere. Didn't chuck the oil but maybe I am alone on this.

alive&kickin - 22-1-2016 at 18:19

As far as oil goes, the best I've found is avocado oil. Advantage-very high smoke point, Disadvantage- not really the cheapest oil out there and sometimes harder to find. I usually use soybean oil for most of my needs (cheap and easy to get) and avocado oil in rare circumstances where I need the higher temps.

careysub - 22-1-2016 at 18:26

I have been looking around for the best bath liquid (not necessarily 'oil') for both high temperature performance and cost.

It looks like avocado oil costs around $17/qt.

OTOH, I just found that Firefox-FX has dibutyl phthalate for $13.15/qt. This is said to be the best bath liquid by a number of SM members, with a BP of 340 C.

The Volatile Chemist - 28-1-2016 at 08:33

Huh. Can one reuse the oil from an oil bath multiple times? Is this 'standard procedure' in professional labs?

careysub - 28-1-2016 at 08:56

I can tell you that cooking oil is reused many, many times in restaurants - and that comes into direct contact with food, both as a source of contamination (of the oil) and as a contaminator (of the food).

So I imagine use where the oil does not come into contact with a decomposable chemical (normally) and where imparting flavors is not an issue the reuse potential would be even higher.

The Volatile Chemist - 28-1-2016 at 13:39

OK. Just curious. I was asking about professional chemists, but I guess they probably don't use oil baths much.

immunetoN-rays - 27-4-2016 at 19:29


I like the electric skillets. They're only a couple of inches deep, but have pretty good thermostatic control. Find one with a circular heating element and an aluminum pan like my old Presto model($5.00 at a garage sale), and you can use it with a magnetic stirrer underneath. (the circular heating element leaves the center clear )
They're only good up to 200 or 225 C, but brand new off-brand ones can be less than $20 American,( which we still call a Jackson, but will be calling a Tubman a few years from now. And why not? It's silly having the man who started the panic of 1837 on a piece of currency. ). They heat fairly fast with anywhere from 600 to 1500 watts depending on the model.
I did my first vacuum distillation on that thing and I still use it whenever It'll do the job. Using it for chemistry keeps me from using it for potato chips and fried chicken, which I already eat too much of.


Artemus Gordon - 28-4-2016 at 15:39

<a href="http://jonbarron.org/diet-and-nutrition/healthiest-cooking-oil-chart-smoke-points#.VyKec_krLq4">Cooking oil chart with smoke points</a>

JJay - 28-4-2016 at 15:48

I use soybean oil since it is the cheapest and one of the best. I'm working on making the transition to a copper bath.