N2 flush when running fresh frozen

Is it really needed to flush with n2 when running a cls with jacket columns and n tane while running fresh frozen? My buddy doesn’t wanna run the frozen until we get a new reg to flush the end with n2. I thought only need n2 flush when running propane?

I don’t think it is. How are you chilling your column and your collection base?

Column has a jacket with dry ice and Ppg or iso to reach cold temps. Collection base is jacketed as well with ice water flowing thru with active recovery cmep

Not that good on active recovery… but your probably gonna have a problem if you collection tank can’t reach the same temp or under temp of your material column. Your creating a vapor lock between the two spots. I don’t even know if a n2 push is gonna solve this problem.

I’d work on a solution to get your collection base colder than water cause water freeze at 32f. Butane condense at around that temp. Your not able to condense the vapors in the collection. At those temperatures efficiently.

At least this is what it sounds like to me. I’m pretty good with passive recovery and I can do that no problem with passive this should be much easier active.


Ya your making a lot of sense now to ponder for a sec. just smoked a blunt an I’m baked haha well if the column is say -110 then shit how would you get th collection. That cold? This is on a terp mk4 btw. I’ve heard nitrogen will fix the problem but it I haven’t tried it yet

You don’t absolutly need it, it just helps push solvent/blows residual liquid from the column. This helps with collecting the cold liquid solvent before you bake the column out with heat during recovery. make sure you cool your collection pot, otherwise you need a sucker tank on ice.


Sucker tank on ice?

With active recovery and cold collection it’ll just be pretty low pressure for the cmep no?

If you have pump you’ll be fine, in a passive system you would need a sucker tank to inject into a heated collection pot.

Ok thats what I was thinkin. What you think, flush with n2 then collection raise pot to like 65 to preserve terp and just enjoy the slow recovery? I normally recover at 95 but mostly run crude

inject cold, into a cold pot. After injection dump the nitrogen off the headspace via the pressure relief valve. You can warm up and begin recovery, it should recover at a normal rate.

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Cool thanks man stoked to run these dry ice columns just want to be safe and efficient

What psi you think I should flush at? Set the reg to like 40 psi on the N2?

that all depends on the pressure inside, start on the low end and see what works for your machine.

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I have a terp mk4 I’m a test this on and a 4 column rack as well rated to 150 psi. But my new question would be so when your bleeding off the n2 from the headspace won’t that introduce air into the system? What about the vac going to the cmep ? Should I add a ball valve somewhere to prevent a loss of vacuum?

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No… when you vent your N2 out of your head space you’re pushing OUT of the system, lowering your inside pressure. You wouldn’t let anything in unless you leave it open and let it get to atmosphere. I only vent til I get back to around 10-12 psi.

Im gonna go ahead and say nitro is probably necessary. If not you’re gonna have a hell of a time. I don’t even run cold and I use it and would never have it any other way.

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Thanks for the clarification. What you got your reg set to on your n2 tank?

All the nitrogen should be positive pressure in the system, stop shy of 1 psi if backflowing air is a concern. We have 3 psi cracking pressure check valves underneath the pressure releif valves, not specifically for burping the tanks, but because most pressure checks will leak under vaccum.


You da man thanks

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I usually stay around 40psi for my columns