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The search for a proper recovery pump..

Gray Wolf

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Both were on my list but that just got moved to the top thanks for the advice

Basically just vacuum distilling the butane and and condensing it in your refrigerant tank before it enters the pump. Or would that still be slow?

I don't see how that could work. A pump that stops moving molecules along, stops pumping.
 
I don't see how that could work. A pump that stops moving molecules along, stops pumping.

I was thinking if you seal the collection pot leave the refrigerant tank under deep vacuum as the butane boils off it will create pressure and only have no choice but to go to the refrigerant tank that is under vacuum correct? Basically just making your refrigerant tank a giant cold trap ?
 

Chonkski

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I was thinking if you seal the collection pot leave the refrigerant tank under deep vacuum as the butane boils off it will create pressure and only have no choice but to go to the refrigerant tank that is under vacuum correct? Basically just making your refrigerant tank a giant cold trap ?

In a way, you are thinking of passive recovery?
 

Gray Wolf

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I was thinking if you seal the collection pot leave the refrigerant tank under deep vacuum as the butane boils off it will create pressure and only have no choice but to go to the refrigerant tank that is under vacuum correct? Basically just making your refrigerant tank a giant cold trap ?

Sorry, I'm still not clear where your pump fits into your scenario.

If you pull a vacuum on the system to remove the non condensible gases, and valve off the vacuum pump, when the butane is introduced to the system, there is no longer a vacuum.

If you heat the butane container, and chill the receiving container, the butane will transfer to the colder container, and depending on how much heat you use, will leave the heavier elements behind in the original container.

That is passive recovery and you can speed up that process using a refrigerant recovery pump, but not a rotary vane vacuum pump, because it is not meant to operate under those conditions.
 

knowhere

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swagelok makes some wonderful high flow pressure regulators you can have them adjusted with special springs so that they work at a variety of pressures / vacuum , they are not cheap but they are stainless steel and teflon and will fit the bill for the regulator portion of the equation,. the key is to get the high flow ones and to do the math so the pressure drop / vacuum to prreessure range and flow co efficiency match up so they are not so much of a bottle neck in the system configuration ( I should work in sales for swagelok )
 
Sorry, I'm still not clear where your pump fits into your scenario.

If you pull a vacuum on the system to remove the non condensible gases, and valve off the vacuum pump, when the butane is introduced to the system, there is no longer a vacuum.

If you heat the butane container, and chill the receiving container, the butane will transfer to the colder container, and depending on how much heat you use, will leave the heavier elements behind in the original container.

That is passive recovery and you can speed up that process using a refrigerant recovery pump, but not a rotary vane vacuum pump, because it is not meant to operate under those conditions.

I don't mean seal the vacuum off, I mean seal off the upper chamber with your weed and the overflow valve so the butane doesn't go up there just basically making a straight path to the refrigerant tank with one line so that as the butane boils off and goes through the line into refrigerant tank, where you can condense it.. correct? More like a rotary evaporator or just along the lines of traditional vacuum distillation?
 
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Permacultuure

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I don't mean seal the vacuum off, I mean seal off the upper chamber with your weed and the overflow valve so the butane doesn't go up there just basically making a straight path to the refrigerant tank with one line so that as the butane boils off and goes through the line into refrigerant tank, where you can condense it.. correct? More like a rotary evaporator or just along the lines of traditional vacuum distillation?

Are you just wanting to passively recover into your storage tank after a run? Just heat your collection vessel and chill your vac'd storage tank........

Butane wants to go to the cold.....
 

Chonkski

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Yes but would it be possible to speed it up with a vacuum or is that not safe?

Well you are initially displacing full vacuum with the liquid/vapor butane in the first place.

So if you're talking about pumping butane vapor through the pump to relieve pressure or something, nope that's not safe.
 
Well you are initially displacing full vacuum with the liquid/vapor butane in the first place.

So if you're talking about pumping butane vapor through the pump to relieve pressure or something, nope that's not safe.

No, butane would never go through the pump, it would be condensed in the refrigerant tank. I vacuum distill ethanol the same way... its just vacuum distillation
 
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SkyHighLer

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I gave you a thumbs up for the diagram! ;-) For the vacuum pump to add energy to the system it has to effect something, and in this case it only has molecules of butane to suck, which will exit the exhaust port.
 

A6 Grower

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I guess if your condensing coil and recovery tank were -100f the butane might be stable enough to use a VERY slight vacuum but i dont think vacuum distillations work or is safe with flammable gases lol. Liquid is a whole different story, i also do this with a similar setup as your diagram to recapture my ethanol and other random experiments....
 

Gray Wolf

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There is really no such thing as a vacuum, only a reduction in the number of molecules occupying a space. If there were zero molecules, you would have a perfect "vacuum."

You can theoretically achieve zero molecular activity at zero degrees Kelvin, even with the molecules present.

A vacuum pump works by mechanically moving molecules along, thus reducing the number of molecules left in a given space. Other molecules are pulled along with the ones being mechanically moved along, because of intermolecular forces, such as Van der Waal.

The fewer number of molecules to move along, the further apart they are, and the less attraction they have on each other, so continued evacuation becomes increasingly more difficult as the absolute pressure drops.

As I and Skyhighler noted, a pump that has nothing to move along, can't pull anything along with it, so if your trap was 100% effective, nothing would be pumped.

What you would have at a low enough temperature, would be a cryopump, which is just passive recovery at lower temperatures, not requiring a mechanical vacuum pump.
 
There is really no such thing as a vacuum, only a reduction in the number of molecules occupying a space. If there were zero molecules, you would have a perfect "vacuum."

You can theoretically achieve zero molecular activity at zero degrees Kelvin, even with the molecules present.

A vacuum pump works by mechanically moving molecules along, thus reducing the number of molecules left in a given space. Other molecules are pulled along with the ones being mechanically moved along, because of intermolecular forces, such as Van der Waal.

The fewer number of molecules to move along, the further apart they are, and the less attraction they have on each other, so continued evacuation becomes increasingly more difficult as the absolute pressure drops.

As I and Skyhighler noted, a pump that has nothing to move along, can't pull anything along with it, so if your trap was 100% effective, nothing would be pumped.

What you would have at a low enough temperature, would be a cryopump, which is just passive recovery at lower temperatures, not requiring a mechanical vacuum pump.

Got ya, thanks, Yes Im just trying to achieve passive recovery with lower temps and quicker speed by keeping it under high vacuum, but I guess it would just lower the temp and not speed things up?
 
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