Did you like it that way? Fighting positive pressure for those cmeps doesn’t sound like a good time. But, cooling the tank giving it a vacuum and your pump will work easier, but still slow you down.
You can use the coil for phase change, cool the tank and go passive. Then you’ll speed up
@Dred_pirate I just wanted to give the inline coil a try but it did take a long time to recover my solvent so my next run I’m going to run dry ice with iso alcohol to the coil inside my solvent tank and use n2 to push… if you have any tips that would be appreciated. Thanks for all the feed back and support.
When you get your tank cold, it should get below zero pressure, starting to pull vacuum. That’s when you can use the nitrogen to push the solvent through your material. If you are pushing multiple columns you can probably leave the valve open and keep pushing to keep the solvent moving into the next column with the same pressure.
If you have a possibility to push nitrogen from the top of your columns, that would be ideal. Once you get enough solvent going out of the columns into the collection. You can vent out the nitrogen pressure and right around zero, you’ll want to stop. And if you have the right equipment to remove it, you can vac out your nitrogen. Not deep vac. Just that top nitrogen vapor in the tank.
Again, your tank should be cold enough to have negative pressure before adding nitrogen.
Once you get everything into the collection. Warm it up and recover. If you leave the pump there. Turn it on and go. Or, open valves and let her rip
@Dred_pirate actually I do have the ability to push n2 from the top of my columns so what would process be like? Step 1 get my solvent cold to a - negative pressure then push with n2, step 2 shit the solvent tank off them use n2 to push the solvent into the collection pot. Step 3 release the n2 pressure then recover?
You may have to remove the nitrogen that you pushed from the columns, it’ll make its way back to the tank. And after going through the condensing coil and into the tank (that’s being held far colder than boiling point) it may need to be removed again. Close off the tank if you are going to do this again. After that is done, you can warm the collection and let it warm up the solvent for recovery
Swage, or hamlet hold up the best
One thing, I’m assuming most of what Dred is saying is assuming hes dumping the entire contents of his solvent storage tank each time? (Or am I wrong?)
Also, get your pump off the floor.
No. Done properly, I’m just taking out the nitrogen.
Right on, just wanted to clarify as I know a lot of passive guys do use that method
If my tank was capable of dumping the entire contents, for each run, that would be ideal. But, the diptube stops quite a few inches from the bottom of the tank and leaves 15~ lbs maybe more in there. My tank is always held -75/80, the only vapors I’m pulling out is the nitrogen. Putting back at negative pressure
Very good, carry on sirs.
One recommendation I have to a lot of people running larger (especially nitro) systems is to always have a vent line somewhere on the system running straight outside. A simple air compressor hose will work for this, no need to buy a solvent hose. You’d be surprised how often this can come in handy.
Hah, there ya go. That comment was direct mainly to the creator of the topic 
Mines permanently plumbed on a custom manifold. Really helps things move along.
I was showing more for them, too. And glad you asked the questions to make it easier to understand for the OP, as well.
@Dred_pirate what’s the proper way to vacuum my solvent tank? Get it cold and pull full vacuum to -30?
I don’t pull full vac. I just take out the nitrogen.
you also have a semi-permeable membrane salvaged from a Nitrogen generator so that your vacuum pump only pulls N2 right?
most folks don’t have such technological wonders installed & imo should probably not be sucking on their solvent tanks when there is liquid in them.
other end is in the employee smoking area in the parking lot right?
I had an N2 vent just like that once upon a time.
Even venting an n-butane tank that was at -30C it would set my meter off.
(which is why I would be concerned about pulling vac)
Actually had to poke my head outside to check that there wasn’t an impromptu gathering in the parking lot every single time. I was much happier once that line was plumbed directly into the exhaust ducts.
With controlled release to exp ventilation and using a compatible vac pump it will only be removing the nitrogen from the tank. Having the membrane is definitely the best way to go about it, agreed.
When I vent off, I even entertain myself and put my sensor near the vent and it doesn’t register. I am also far colder than -30. But, it’s not boiling off.
But, think about the science. What’s the boiling point of butane? 0c/30.2f anything above that it will emit pressure. Anything below that, it doesn’t emit pressure. The further below that, it pulls vacuum. It’s science, it doesn’t care what you think. I am removing the nitrogen head pressure that is above my solvent pulling a vacuum on its own. I’m not pulling a vacuum to micron like a short path. I’m pulling a vacuum that is only removing the nitrogen.
And yes, I plan on getting a membrane, once I find a manufacturer that I can supply myself with one.
