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Author: Subject: Temperature Control for an electric Oil Bath
Bikemaster
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[*] posted on 11-3-2010 at 07:15


Mineral oil is really good for for a bath fluid, but not really at high temperature http://www.hartscientific.com/products/bathfluid.htm
It only rate acceptable up to 175 C, but if you don't need these temperature, it seem to be a good issue.
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javagamer
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[*] posted on 11-3-2010 at 12:07


Oh, what's the problem with mineral oil beyond 175? It doesn't start to boil until over 300 iirc. Either ways, I know my hardware store has linseed oil, so if I need any I can just get it.
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Lambda
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[*] posted on 11-3-2010 at 15:13


Hi @javagamer,

If You decide to build your own Thermostat, then switching with a Zero Crossing Solid State Relay will give considerable less Switching Distortion. On eBay, they are real Cheap, going for about $5-10

Also, I strongly recommend You to put one or more Thermal Fuse(s) in Series with the Heater Element in the advent of Circuit Failure to prevent overheating and Ignition of Your Oil Bath. They are real Cheap too, so You really should NOT omit this extra safety feature into Your Oil Bath Thermostat Design. Boiling, and Burning Oil is just too Dangerous !

Kitchen Oil Fire ! :o



You can Buy Thermal Fuses in any Shop that deals in Espresso Coffee Machines (>100 °C for High Pressure Boiling Water and Steam) and Oil Frying Pans (like those used for French Fries / Chips).

Thermal Fuses:
http://www.ivaldi.fr/pages_anglaises/regul-ftus.html
http://www.cantherm.com/products/thermal_fuses/index.html

For a little Info on Solid State Relays, and Zero Crossing TRIAC Driver Chips, You may find a few useful Tips here:

Schematic for Electrolysis Device:
https://www.sciencemadness.org/whisper/viewthread.php?tid=13...

And for Schematics on Thermostat Devises, You may find a few useful Links here:

Thermostat Schematics:
http://images.google.nl/images?um=1&hl=nl&client=fir...

David Bowie & Pat Metheny - This is Not America (1998):
http://www.youtube.com/watch?v=0YUe786PYUk

Lambda
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Lambda
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[*] posted on 11-3-2010 at 20:32


Quote: Originally posted by javagamer  
... Either ways, I know my hardware store has linseed oil, so if I need any I can just get it.


Linseed Oil can Polymerize and the reaction is Exothermic, and Rags Soaked in it can Ignite spontaneously. Due to its polymer-like properties Linseed Oil is used on its own or blended with other oils, resins and solvents as an impregnator and varnish in wood finishing, as a pigment binder in oil paints, as a plasticizer and hardener in putty and in the manufacture of linoleum.

A Devastating Shop Linseed Oil Fire (I guess that this Unfortunate Guy should NOT have left Linseed Oil Impregnated Rags lying around after all):





@javagamer, I am just trying to Boost Your Confidence !! :D, and I would think twice about using Linseed Oil !!!

Why not use Solid Paraffin (Candle Wax, can also be Stearic Acid, seldom Beeswax nowadays) which can have Boiling Points in excess of 450°C, or Vaseline (also called Petroleum Jelly, Boils at about 350°C) instead ? :cool:

n-Paraffins:
http://chemicalland21.com/petrochemical/n-PARAFFINS.htm

Vaseline (Petroleum Jelly) MSDS:
http://www.bmed.mcgill.ca/REKLAB/manual/MSDS/Materials%20Lis...

Hot Chocolate - So You Win Again:
http://www.youtube.com/watch?v=WJvdy00LcPI

Lambda
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[*] posted on 11-3-2010 at 20:57


Quote: Originally posted by javagamer  
Oh, what's the problem with mineral oil beyond 175?


Flash, autoignition, and smoke points. Flash point is the temperature it is 'easy' to ignite the hot material and generally is around the temperature that fumes start to be annoying while the smoke point certainly is where fuming/smoke is a problem.

Partially hydrogenated peanut oil is used for frying in some areas because its smoke point is reasonably high (~220-230 C), it's untreated level of poly-unsaturates is fairly low so it doesn't need too much hydrogenation, and the crop is grown locally so it's not too expensive. Cottenseed oil is another.


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[*] posted on 12-3-2010 at 05:00


I note the vaseline MSDS states to "keep away from heat and other sources of ignition".
Candle wax should be OTC and relatively cheap.BTW I didn"t recommend linseed oil for use,merely stated that I have used it with no problems,then invited further discussion.The cheap(non medical) mineral oil (parrafin oil in Australia) always had excessive fume problems even at relatively low tempreatures.
If I could find a non chem-house supplier of high grade silicon oil I'd do as Entropy 51 and make the investment.




Chemistry- The journey from the end of physics to the beginning of life.(starman)
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[*] posted on 12-3-2010 at 17:25


Haven't tested it with anything but water yet, but so far it seems like a very good investment. Thanks for all your help everyone.
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[*] posted on 7-4-2010 at 12:26


Check out the fry daddy - actually made for hot oil
http://www.walmart.com/ip/PRESTO-FRY-DADDY/9219298

My partner uses Grapeseed oil regularly with no fires - temperatures in the mid 200 C range. You can get it a lot cheaper on ebay than trying to buy it local.

I thought I had a cool idea to replace sand in a sand bath with silicon carbide until my sweetie pointed out that might be a bit rough on the glassware....

Suzee
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[*] posted on 1-5-2010 at 03:37


Quote: Originally posted by SWilkin676  
Check out the fry daddy - actually made for hot oil
http://www.walmart.com/ip/PRESTO-FRY-DADDY/9219298

My partner uses Grapeseed oil regularly with no fires - temperatures in the mid 200 C range. You can get it a lot cheaper on ebay than trying to buy it local.

I thought I had a cool idea to replace sand in a sand bath with silicon carbide until my sweetie pointed out that might be a bit rough on the glassware....

Suzee


Dammit! :D I was just about to post that.

A deep fat fryer.

You can get them at any well stocked outlet of cheap electrical products.

Sure, the dial might not be calibrated properly, but that's what a thermometer is for. I wouldn't trust the dial temperatures on anything and, besides, the actual plate temperature isn't the issue, it's the solution temperature. Even people like IKA put external temperature probes on the plates that cost upwards of a 1k a piece.
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[*] posted on 1-5-2010 at 08:45


Would DOT-5 silicone-based brake fluid be useful? DOT-5.1 glycol based fluid? Both should be useful at 200C. The glycols absorb water and their boiling points go down. It's not clear how to remove absorbed water. Maybe anhydrous MgSO4 or something like it would work.
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