Author Topic: RE: Heating sand baths  (Read 73 times)

hypnos

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RE: Heating sand baths
« on: June 23, 2011, 09:19:18 AM »
 I have noticed from time to time that, although sand baths have many virtues, not too may people use them because of  'the time they take to heat up'

  Its found steam can "convect" heat  Through and TO All the sand particle Very quickly i.e
 
 Heat 5-10cm sand baths rapidly by allowing a small amout of water to boil in the bottom of the container

 The steam will travel quickly through the sand and heat it to at least 80c surface temp in several minutes---the same applies to evenly heating plates--put a teaspoon of water on a hotplate hot enough to make the water boil and 'ride' on it's own steam, then put your plate upon it--AS LONG AS the plate ISNT REALLY COLD <10c and is sturdy,thermal shock should not be a problem- it will take about 30 seconds to reach 90+c allover through the steam convecting the heat to where its wanted ;)

  Hope this helps someone   Hyppy
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Shake

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Re: RE: Heating sand baths
« Reply #1 on: June 23, 2011, 10:15:07 AM »
if you had ever distilled anything youd know that under vacuum one is not in a rush to hit 100c as that can be well over the BP of the substrate.

The problem with sand baths is the radiant heat and the time they take to cool down if one over shoots when fractioning.

also, sand baths are notorious for blowing heating elements.

thanks anyway

akcom

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Re: RE: Heating sand baths
« Reply #2 on: June 23, 2011, 04:40:43 PM »
mantles or silicone baths.  I really don't see a need for anything else.

hypnos

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Re: RE: Heating sand baths
« Reply #3 on: June 23, 2011, 06:12:42 PM »
sand just seems a little more "Stable"' to me,,I've knocked over, to varying degrees, water baths AND heating mantles (dont ask...its embarassing,,I "fell" on it! Actually only on its corner,BUT, what a MESS...and I HATE Dramas

"under vacuum one is not in a rush to hit 100c as that can be well over the BP of the substrate."  yeah true, but thats under Vacuum, and many refluxes dont need to be "under vacuum",,whereas distillations,especially 'fractional distillations can be finicky, However MANY proceed at Over 100c

also, sand baths are notorious for blowing heating elements.

 Why?
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antibody2

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Re: RE: Heating sand baths
« Reply #4 on: June 23, 2011, 06:41:51 PM »
Thanks Hypnos, not a bad idea at all.

Actually - under vacuum is the only place I use a sand bath. It will accommodate a RB flask of any size, doesn't stink (like an oil bath) and doesn't cost a dime. Been doing this for years and I have never blown an element. Buying mantles for every size of flask I have would get expensive. If I'm not using vacuum, I use a FB flask and set it directly on the hotplate.

hypnos

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Re: RE: Heating sand baths
« Reply #5 on: June 23, 2011, 07:13:12 PM »
 "It will accommodate a RB flask of any size, doesn't stink (like an oil bath) and doesn't cost a dime"
 
         Couldnt agree more AB1, and with some careful thermometer placement,,you will get consistent readings,once its attained the 100c from the evaporating water--IMO many people avoid sand baths, due to the time they took to attain "useable temps'
 personally I felt the same way , until i discovered this technique (plus I Hate the smell of Brake fluid!)
"the two things you can give away and never lose, are what you know, and how you feel...."