supercritical co2 extraction - diy community?

[Fadedawg]

Rating and testing are different. A ASME tank tested to 9000 psi, would be rated at 3000 psi. Here is the experiments that we performed:

15.24 DIY SCFE CO2 - GrayWolf's Lair (graywolfslair.com)

Ostensibly, using heat instead of pumps will expose your material to a more wider pressure/temperature curve. Even if you heat the CO2 in a separate tank, as soon as you start transferring to the process tank, the pressure will fall.

 

[vapeitgud]

Rating and testing are different. A ASME tank tested to 9000 psi, would be rated at 3000 psi. Here is the experiments that we performed:

15.24 DIY SCFE CO2 - GrayWolf's Lair (graywolfslair.com)

Ostensibly, using heat instead of pumps will expose your material to a more wider pressure/temperature curve. Even if you heat the CO2 in a separate tank, as soon as you start transferring to the process tank, the pressure will fall.

Yes, thank you. Now that I take a closer look the aluminum CO2 tank has a service pressure of 1,800psi, and a 3,000psi pressure test. Whereas the carbon fiber tank has working pressure of 4,500psi, a pressure test at 7,250psi, and a minimum burst pressure of 15,000psi. (Those are rounded, it actually has 30 mpa, 50 mpa, and 102mpa)

Yea, without a pump to regulate the pressure it will be unavoidable to lose pressure throughout the process. Maybe after I get this up and running I will run some tests doing shorter cycles with larger tanks to minimalize the pressure difference. (As in using only 4# of C02 from a 20# tank)

 

[vapeitgud]

Fadedawg do you know anything about solenoid Valves? I want to use one to let out bursts of the liquid CO2 into the collection vessel for depressurization. But I am having trouble understanding how they are rated for pressure. I can't find any that mention pressure above 145psi, but a few of those mentioned wog 1000. Do solenoid Valves have two different pressure ratings for different things?

 

[Fadedawg]

WOG means water, oil, and gas service.

Check out "high pressure solenoid valves" for higher ratings. IE: high-pressure solenoids | McMaster-Carr

 

[vapeitgud]

WOG means water, oil, and gas service.

Check out "high pressure solenoid valves" for higher ratings. IE: high-pressure solenoids | McMaster-Carr

Thank you, I was able to find one with ease thanks to your link.

 

[vapeitgud]

@Fadedawg

I'm back with another question! It's been awhile, I got a couple 6,000psi 316 stainless steel pressure vessels. After that I turned my time, attention, and effort elsewhere, and have recently revisited this topic. I'm pretty clear on what I need to get for the pressure vessels, so expect updates on that in the future. What brought me here today are the 8g-45g "rechargeable" CO2 cartridges. I mentioned wanting to use these in earlier posts, but was unable to find a way to get active flow through one. The issue being the bottom fill port has female M5-0.5 unf threading, which is rather limiting. So I gave up on the active flow. Opting instead for a passive system that is charged either through packing the vessel with dry ice(which is easy given the cartridge unscrew at the center), or filling from a CO2 tank with a CGA320 to NPT 1/4 Adapter. The CO2 cartridge is threaded for UNF 3/8-24 male and the needle valve needed for slow decompression is threaded for NPT 1/4 female. I was only able to find one company(XS Scuba) that sells a stainless steel adapter, and it doesn't come with much for details. It also doesn't include a sealing washer or o-ring. Which brings me to my question:

What type of material is best suited to CO2 extractions both subcritical and supercritical in the 600psi-1,300psi, and the 21°C-35°C range?

I already have all the parts either in my possession or on the way, including some seals. I will be testing it out within a half month.

Thanks for all your help this far!

 

[Fadedawg]

PTFE works but isn't highly resilient. Have you checked out FEP encapsulated O-rings?

McMaster-Carr

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[vapeitgud]

PTFE works but isn't highly resilient. Have you checked out FEP encapsulated O-rings?

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

No, I hadn't checked out FEP. I ordered both nitrile o-rings, and nylon flat washers. Which are at the lower end of resiliency, but are also very cheap and replaceable.

I was looking at getting some EPR, or EPDM ones, but I was having some trouble finding the right size(admittedly I didn't look for long). FEP looks ideal if I want some longer lasting seals.

Thank you once again! Your advice has been invaluable along my journey. I will update with results of my test run soon.