4 ms·
why it can't be vacuumed?
by hippich 11y ago
why it can't be vacuumed?
- klodolph 11y agoIn a vacuum, the head would crash into the platter. The gas provides a cushion. Flying height these days is something like 3nm (yes, you read that right), so the tiniest vibration could cause a head crash in a vacuum.
- Retric 11y agoSure, but at say 1/10th atm Nitrogen would seem to work. So, the question becomes why is helium significantly better?
- ScottBurson 11y ago> at say 1/10th atm Nitrogen would seem to work But then you have to have a case strong enough not to bend under the pressure difference. At 1 atm, of course, helium has much lower density (and therefore lower viscosity). Nitrogen weighs 28 g/mol; helium just 4 g/mol.
- samstave 11y agoSo in measurements of standard helium rubber party balloons, how many drives could one fill with Helium from one such balloon?
- bdavisx 11y agoWhat about Hydrogen? Too reactive with metals?
- hga 11y agoVery much so: https://en.wikipedia.org/wiki/Hydrogen_embrittlement https://en.wikipedia.org/wiki/Hydrogen_embrittlement And it's generally reactive stuff. Helium is a nice, nonreactive noble gas.
- lfowles 11y ago> Flying height these days is something like 3nm (yes, you read that right), so the tiniest vibration could cause a head crash in a vacuum. Wikipedia goes on to say the head could crash into a fingerprint or _smoke particle! So... how did my spinning rust laptop drive ever survive on my lap?
- hga 11y agoA HEPA or the like quality air filter to equalize air pressure, which doesn't pass much air anyway.
- ratsmack 11y agoThe heads need a gas of some sort to float on.