2026-08-31 03:42 UTC
i’ve noticed biologists keeping CO2 cylinders connected to something near their -80C freezers, that’s why i assumed it works for this kind of temperatures
Replies (1)
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@Canonical_Warlock@lemmy.dbzer0.com 2026-08-31 21:16
Might be for keeping an inert atmosphere. Normally nitrogen would be the gas of choice for that but CO2 is cheaper and easier to store in bulk so if they don’t absolutely need nitrogen then I could see CO2 being used instead. Basically you just keep the chamber slightly positively pressurized with CO2 to keep the oxygen out. As far as temp keeping goes though basically all of the ultra low temp freezers (those not using liquid nitrogen anyways) I’ve seen use R-508b along with a medium temp refrigerant like R-404a or R-448a in a cascade setup to achieve those temps. I’ve never seen CO2 used for ultra low temp refrigeration due to it’s nasty habit of turning solid below about 100PSIG.