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Comment by Out_of_Characte | Hacker News Reader

Assuming a drive contains helium at standard temparature and pressure, and contains about a liter in volume. That would be about 1 gram worth of helium per drive.

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0.05 gram Helium assuming: (1) half of drive volume is used for platters, (2) at 15° Celcius (3) at 1 atmosphere (I'm guessing not pressurised since that would defeat purpose of using Helium, although might be less than 1 atmosphere)..

0.376 litres for total 3.5-inch HDD volume from my first Google result: "Width: 101.6 mm, Height: 25.4 mm, Length: 146 mm". Actual volume used for platters is less than that.

Helium is light ~ 0.169 g/litre from "0.169 kg of Helium is 0.999 m3 at 15°C": https://microsites.airproducts.com/gasfacts/helium.html Note that I think comment assumed one litre of normal air not Helium: "The density of dry air is 1.2929 g/litre at STP".

One MRI machine uses about 2,000L of liquid He, which expands to around 1:770 in gaseous form. So roughly 1,540,000L of helium gas per machine.

GE says over its lifetime (roughly 13 years) an MRI machine will use about 1e4 litres of liquid helium. Two thousand litres is a good estimate for the capacity of a machine, but it's not a useful figure unless you know how often you need to replenish it.

MRI machines borked the MEMS accelerometers in iPhone due to helium contamination. I assume most smartphone sensors are now helium-tolerant.

Nope. They just added a warning so it's your fault if you get any helium atoms in your oscillator.

https://support.apple.com/guide/iphone/important-safety-info....

Legalese - even cheaper than engineering, apparently.

Hard drives are much, much smaller than one liter.

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