Do you lose weight purging BHO?

DreamTime

Member
The thing about vacuum enviornments, is that boiling points depend on air pressure... This is why vacuums are so good for purging oil... It drastically lowers the already low boiling point of butane, so we can purge more readily/rapidly at room temperature with minimum heat... So ideally, if we created enough of a vacuum for long enough, we COULD remove some terpenes from the oil. It's not a concern, but I just wanted to clarify that it's possible with a vacuum environment.
Good point. Fortuantely, the boiling point of butane is soooo much lower than everything else we are trying to get rid of, the butane should be long gone by the time any terps would be noticably affected.

If anyone is interested, there is a cool online tool for calculating boiling points that will let you include air pressure as a variable so you can estimate what will happen in your vac chamber as the air pressure drops: http://www.trimen.pl/witek/calculators/wrzenie.html
 

Matt Rize

Hashmaster
you have to take into account the resin viscosity, which does not change under vac.
the tane can't boil out if the resin is too viscious. thats why we do gentle heat and 28+
 
Good point. Fortuantely, the boiling point of butane is soooo much lower than everything else we are trying to get rid of, the butane should be long gone by the time any terps would be noticably affected.

If anyone is interested, there is a cool online tool for calculating boiling points that will let you include air pressure as a variable so you can estimate what will happen in your vac chamber as the air pressure drops: http://www.trimen.pl/witek/calculators/wrzenie.html
I used that calculator and the results show I'd be boiling off THC way before a full vacuum just at room temperature. To use the calculator you need to know the boiling point of THC at 760mm of Hg is 157C/315F (from THC at Wiki,) also you need to CHOOSE "high molecular or high boiling point compounds" to get in the ball park for "heat of evaporation" factor, then you're good to plug in vacuum values and make your own table. You'll want a vacuum pressure unit converter, I'd post a link but fear moderation. ;-) Peace, John
 
I used that calculator and the results show I'd be boiling off THC way before a full vacuum just at room temperature. To use the calculator you need to know the boiling point of THC at 760mm of Hg is 157C/315F (from THC at Wiki,) also you need to CHOOSE "high molecular or high boiling point compounds" to get in the ball park for "heat of evaporation" factor, then you're good to plug in vacuum values and make your own table. You'll want a vacuum pressure unit converter, I'd post a link but fear moderation. ;-) Peace, John
The exact "heat of evaporation" factor for delta 9 THC is 66.49 kj/mol (guy at TokeCity found it, but he didn't realize vac purgers were pulling a vacuum deeper than 1,000 microns while the two stage rotary vacuum pumps are pulling below 100 microns, often down to 25-50 microns, so he thought the facts proved THC wasn't being boiled off, such a beautiful presentation only to reach the wrong conclusion...) So, here's a scan of the vacuum conversion table with some of the corresponding correct boiling points for delta 9 THC (btw, "the heat of evaporation"/"enthalpy of vaporization" for n-butane is 22.41 kj/mol if you'd like to see the numbers of just how low a temperature the residual butane comes off at under vacuum...guy at TC deserves a round...)

Scan025.jpg
 

Fadedawg

Well-Known Member
Yes you lose weight, because the butane you are purging out weighs something.

If we are discussing final purge, after visable liquid butane is gone, then the loss is very little, because the butane is present in parts per millionth.
 
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