Stanton D. answered • 06/21/19
Tutor to Pique Your Sciences Interest
So Kia T., which condition do you think it will be more difficult to arrange safely, something above 31C or something above 73 atmospheres? Hint: the surface of your skin is already at about 30C!
Of course, it's the pressure that's the problem condition. In general, a machined stainless steel vessel, with a head piece held on by quite large sealing nuts, a compressed O-ring gasket, and fairly heavy-gauge stainless steel tubing fittings (Swage-lok) and pressure gauges would do it. You would also need a large torque wrench to tighten your head-sealing nuts. You are talking an assemblage of at least 10 kg mass. That's for a reasonable-sized chamber (100 cm^3). You MIGHT be able to borrow time on such an apparatus at a nearby engineering company.
Now, high-performance-liquid-chromatography (HPLC) tubing is available which can easily withstand 1500 psig, or about 100 atm. BUT that is with a miniscule volume -- the inner diameter of the tubing is tiny compared with the outer diameter, which is perhaps 1 mm. So the inner diameter might be 50 um. So one meter of such tubing would have a volume of ~2 mm^3. Not very much! You can't make the inner diameter larger, because it's the ratio between the outer and inner diameter that governs the tubing strength. So if you wanted an inner diameter of 1 cm instead, you'd need a column about 20 cm wide -- out-of-sight expensive! But the standard tubing, that's available cheaply, and a scientific supply company might even donate you some, if you can get a researcher somewhere to ask for you.
If you think you might try this in your steam-driven vegetable pressure cooker at home, think again. Such autoclaves are usually arranged to vent at about 30 psig, or 2 atm internal pressure. Only 71 atm to go!
Hope this gives you some ideas, and gets you looking for answers to important questions! (Supercritical CO2 is a tool, not a goal in itself!). -- Cheers, Mr. D.
