Passive Recovery Time


Cool yeah that’s what i figured -50 to -60. So my recovery tank gets pretty damn cold when that liquid starts flowing back in there


How big is the tank? Leave it in a large keg bucket and cover her up


Pros and cons for acetone
gets way colder
Cheaper per gal
Clean up is fastesr
Evaporation rate is way higher so cost is about the same



i have another that doesn’t have legs so i can give it a try and see if there’s a difference. but once the tane is returning my tank gets freezing cold if it’s -60 going in and -60 on the outside i don’t think there’s gonna be that much difference on recovery just a waste of dry ice


That tank is very different. Love the idea. Wish it was jacketed. Does it have a coil inside


Yeah it’s been working great. No Coil on the inside. I just run it into a coil in dry ice and alcohol and then back through it on recovery instead of just chilling the entire solvent tank.


@Dred_pirate That def makes things easier having the chiller on your solvent Tank…
@J12 I Understand know why your using the coil inject for Passive with that Solvent tank on Legs, How cold is your Slurry on your coil? Not sure how that dont stall out… I think With Passive less is more. Shortest lines possible With a Subzero Taking the Heat…


I totally get it. The other tank could do it if you wanted if you had the means. You have your own way.


probably -50 ish it’s just dry ice and alcohol. my lines to and from the coil are 5 feet each. my collection vessel is jacketed and when i flow hot water into the jacket i let the tank warm up until it gets to 45 - 50 psi then open up the ball valve for recovery. it has plenty of push to go into the coil and keep things flowing. The first 2/3 return pretty quickly and the last 1/3 i periodically shut off the valve to get a little more pressure in the tank and then open it back up to get the last bit of tane out. During the beginning of recovery i also have a purge line connected to my tank open until liquid starts flowing into the tank and then close the purge valve after things are flowing. that helps get a nice flow going for me. I also think that helps prevent lock up because if there is any pressure in line that your not aware of its purged out of the tank and allows for good flow


and check valves chatter…sign of work being done!


One thing i’m confused about is how much it has been said to pull a vac on your tanks. I’ve always been led to believe you want zero atmosphere in any component attached to your system which is why we vac everything, including our solvent tanks as deep as possible before filling or running.

Can you confirm this is a correct way to think? @Dred_pirate

For example my tank will be filled with 50lbs of solvent and maybe sit at 10 psi @ room temperature, and when I drop the temp of that tank to -75 it will be damn close to full vac regardless of how much solvent is in it. If I didn’t vac the tank before filling and left some atmosphere in there would that not condense from the cold and be creating pressure?

I’ve witnessed my dewax column filled to the site glass at the top (110% overfilled) and still reading a -25 vac with maybe 3 inches of headspace in a 2" siteglass head.

So surely, as long as I can keep my tank chilled to -75, and my collection/jacket can heat the solvent efficiently it should be screaming to get to that coil and tank.

I remember reading in summit closed loop 101 that running passively renders molecular sieves almost useless because you lose turbulence / starting and stopping of solvent through the filter. Is this old knowledge? Should I still run collection -> mol sieve -> coil -75 -> tank -75?

Much appreciate all the knowledge in this thread. Definitely going to give this a shot and have a feeling like I won’t be looking back at active or rebuilding another fucking pump :sweat_smile:


If I’m understanding you correctly, there should be zero atmosphere in your solvent tank. That’s why we vac everything down as well as for the pressure differentials that make passive recovery possible. I am curious about the mol sieve though, as that’s something I need to be investing in asap.

However, I’m curious as to its (mol sieves) utility if you are purging the system with nitrogen prior to pulling vacuum. I would think this would remove all the atmosphere and 99% of the h20 from the system.


Purging with nitrogen wouldn’t really remove any water. We run passive with a mol sieve. The pressure drop through the beads is almost nothing


Anyone else using a Tankless water heater? I like this idea. Can you Use it with a bucket of water or do u need a hose for constant pressure or a PUmp? I see a few on ebay for less than 200$ for an electric tankless water heater seems like it might be alot more efficent than an immersion circulator…


Constant water input


Have you looked at the electrical requirements for those things.


@Dred_pirate It seems the little guys are same specs as the Vacmaster sous… 1500w 110v for the little guys… i did notice alot are 3200w 220v. Id have to run another dedicated circuit for the bigger ones…but Im guessing that the Little Water heater would be more efficient at keeping the temp Constant compared to a couple Vacmaster Sous. Considering there about the same price I might give it a whirl…
@greggoose710 THANK YOU… So ill still need the pump…


That’s pretty dope. I would be interested if they would work. Keep it far enough away from the extractor so there wasn’t a boom boom problem.


Most of those should be run off of propane or natural gas. Even Home Depot sells them.