Using Positive Pressure and Plastic Drums to Transfer Ethanol at -50

The data sheet says that I can safely pressurize poly drums at around 20 psi. That seems like enough to push ethanol out of a 15 or 30 gallon and into extraction equipment.

But what about at -40, -50, or -60C? -90C?

Anyone out there using positive pressure fluid transfer systems in plastic drums/barrels? Any of you hydro heads?

Finding a pump to operate at temp and viscosity of cryo-ethanol is crazy. I was looking into air diaphragm pumps and I thought to myself, what if I remove the diaphragm pump and use the air compressor to push it out of the drums. I’m not entirely sure what to expect as compared to water. Could be great. Could be a waste of time and money. Mostly time.

I just need the right bung caps and a few manifolds and valves, and I think I can use air to transfer room temp etoh to the drums in the cryo chest freezer, wait six hours, and then use air to top off my extraction machines for another six hours of work without any down time.

Guess what kind of extraction equipment I’m using, and you win, nothing. Because it’s obvious.

5 psi of pressure differential is more than enough to move room temp liquid. 6-7 will move a lot of slurries. I don’t work in plastic much but I’d be surprised if you need more than 10.

And please use n2 or some other inert gas that isn’t air if you’re using positive pressure.

You might find it easier to suck than to blow. We do, in many cases - pressure differentials are pressure differentials.


I’m having trouble finding viscosity data for EtOH at -80 but it seems to increase drastically starting around -50C

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Hey bud, not sure if you want to go this route but I personally use kegs. it can handle positive pressures and -80. I think the poly drum would crack at those temps and thats a bigger problem with pressure behind it for sure. Etoh viscosity doesnt change much with that temp drop. In my experience the temp is what makes using a transfer pump of any kind difficult. Like I said I use kegs from: KEGS and then use a nitrogen tank to pressurize into another keg for cooling or into my centrifuge for extraction. hope that helps you out brother


It most certainly changes…



Certainly a concern.

Once upon a time I claimed

Then came back with

No HARD data…:shushing_face:

They work well at -50C, and don’t seem to embrittle there, but I never gathered solid data below that temp.


Yeah I understand it does. I mean it isn’t to the point where it concerns me and flow rate is fine through a 3/4" line.


Thanks for the info.

I’ve thrown these 15 gallon polys in and out of a cryo at -90 without a single crack for years.

Unless they make a cryo freezer that can hold two 55 gallon drums, the 15 gallon drums fit nicely in a chest cryo with just enough room to pipe in manifolds. A standup may be able to fit them, I’ll have to look into that option.

The kegs would have to be under 27" tall, and I’d have to be able to fit at least five to cover my batches, preferably six. I’d also like to be able to drain and fill them at once.

Ultimately, I’m looking to improve an old system that I know worked. I’m not going to be getting nearly as cold (-50C versus -90C) and I was planning on using 1/2" ID hose out of the containers into a manifold mounted inside the cryo with a 1/2" ID out to the capnas with N2 to push it, 5-7psi.

The way that capnas are filled does not allow for negative displacement. Would be nice, though.

just do vac transfer and save the headache