Comment by Aachen
10 hours ago
I didn't know pressure is used in sterilisation. Trying to look up why that helps, the Wikipedia article on autoclaves does not explain why but says it uses 1 bar, which would be equivalent to ambient pressure (atmosphere at sea level is ~1.01 bar). Does it maybe mean an additional bar, so twice atmospheric pressure?
Wikipedia also says it uses steam, not just hot air, and again doesn't say anything as to why
Do you know why pressure and steam help?
Edit: I may have found it while looking at what I thought was an unrelated part of the rabbit hole. Gravity displacement sounds like antigravity technology but it's apparently the cheapest autoclave type and means "displace using gravity" (by letting gravity do its thing; not adding in a vacuum pump). What it's displacing is air. This matters because
> Steam at 134 °C can achieve a desired level of sterility in three minutes, while achieving the same level of sterility in hot air requires two hours at 160 °C. (—Wikipedia)
I'm now assuming that pressure must help push the air out, and steam is used for having better heat conductivity. Neither is quite spelled out but that's my best guess currently
I'm pretty sure it is because when there is high pressure the boiling point of water is higher.
How would that help? It never says water, always steam, and it needs to get in all crevices evenly which afaik is easier with a gas than a liquid. If the steam condenses to water (for example due to raising its boiling point above the autoclave's temperature of ~125°C) that'd probably be bad
Apparently at 2 bars, water boils at 120°C. The first temperature mentioned on Wikipedia is 121°C. That's awfully close; but elsewhere the article is quite clear about using higher-than-atmospheric atmospheric pressure. I don't see an explanation that fits all the mentioned facts
> If the steam condenses to water (for example due to raising its boiling point above the autoclave's temperature of ~125°C) that'd probably be bad
If water boils at 100C then steam condenses at 99C. If water boils at 120C then steam condenses at 119C.
> higher-than-atmospheric atmospheric pressure.
What does that mean?
> I don't see an explanation that fits all the mentioned facts
Is it really a difficult concept? If the boiling point rises so does the condensation point.