What would happen if the chamber develops a leak somehow, and the gas leaks out ? All data lost and HD fried ? Even if the motor is inside the sealed chamber, there has to vacuum-tight connectors for data and motor speed control. That will make it expensive.
r...
Helium diffuses through solids quite rapidly. It's probably planned obsolescence.
-- Bill Sloman, Nijmegen
On a sunny day (Thu, 13 Sep 2012 20:03:16 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :
Somebody invented a helium tight housing for this, they do not even want to mention how it works. There is some more about this in German on heise.de:
On a sunny day (Fri, 14 Sep 2012 00:51:48 -0700 (PDT)) it happened Bill Sloman wrote in :
You have an 'age fixation'!
man
k-d=3D
Wrong. "Planned obsolescence" is what the Socialist Party talks about. rather than the 50+ Party (who - for those less interested in Dutch politics - are a new political party in the Netherlands who just won two seats in the Dutch lower house).
-- Bill Sloman, Nijmegen
It just wasn't your time...
perhaps THAT is the key. Smaller molecules in a small space yield better bearings. Whay not hydrogen? Or do they bond to make H2 and are actually larger than He?
Safety, I imagine. The marketing department must be disappointed that they can't use H2: "Try our new, high performance hard disks--the Hindenburg Series!"
Cheers
Phil Hobbs
What happens when the He leaks out or the casing bursts at high altitude and the hard disks fall down.
On a sunny day (Fri, 14 Sep 2012 11:57:08 -0700 (PDT)) it happened LM wrote in :
It is even worse if you hang on to your laptop with helium harddisk, it is -40°C up there.
Never heard of vaporware?
Jamie
it's been done for energy storage flywheels to reduce friction. there'll be a reduced bernoulli effect too, perhaps the plan is to get closer to the platter with less downforce.
leakage by diffusion could be a problem long-term,
Exactly my thoughts. Helium is super difficult to keep in, or out of anyth= ing. Some diving watches (omega seamaster for example) have helium purge v= alves so that divers who have spent long amounts of time deep underwater in= a helium atmosphere can vent the built up helium from their watches before= resurfacing. The watch seals are incapable of keeping the helium out.
--Dan
Exactly my thoughts. Helium is super difficult to keep in, or out of anything. Some diving watches (omega seamaster for example) have helium purge valves so that divers who have spent long amounts of time deep underwater in a helium atmosphere can vent the built up helium from their watches before resurfacing. The watch seals are incapable of keeping the helium out.
--Dan
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Old glass HeNe laser tubes will stop working when the He pressure drops too low. They can be repaired by placing the tube in a container that has been flushed with He for about a week. The He diffuses back into the tube.
I'm trying to visualize a dive watch with a case of the bends.
Only $1,750 retail for a watch with a helium purge valve.
My uninformed wild guess(tm) is that while helium leakage will be a problem, the real headache will be helium diffusion into the aluminum casting and possibly through the parylene coating onto the platters. The diffusion into the casting will appear as a gas loss. While the associated dimensional and surface roughness changes will be very small, they might be enough to trash the drive over extended periods. I wonder if the drive will include a fill valve to load and replenish the helium. Maybe also an internal pressure sensor to help refill the drive and warn of impending doom.
perhaps they could put a sealed capsule of helium inside and diffusion out of the capsule could compensate somewhat for leakage from the drive.
A rubber May Day balloon could contain the quite large H2 molecules for several days, however, the He atoms did escape the rubber balloon quite quickly. Have you lately seen rubber May Day balloons in countries, in which May Day hydrogen balloons have been banned ?
Probably a naive question, but if the helium was at a low pressure, would it still diffuse out? If it does diffuse out the internal pressure must drop, I suppose? Where does it end?
Cheers
Atmospheric concentration is around 10ppm, so if you started with 100% pure He at 1 bar, you'll get about 10ubar equilibrium, and of course, you'll have a hard time getting it lower than that.
Hmm, vacuum tubes are regularly 10^-9 torr and less, and have stayed good for a century. Is diffusion through glass, and quality seals, really that slow, or is the partial pressure a lot lower than I recall?
Wikipedia says atmospheric helium is 5.24 ppmv, so I'm not misremembering too badly...
Tim
7TB? Probably glass platters. They do exist in exotic HD design labs. Hard Aluminum has been the standard though. Maybe place a polymer layer before the magnetic layer so the Helium would make no incursion.
Helium IN is easy. Solid casting (or stainless deep drawn can, with a small end lid and single evacuation/fill port/plug and hermetic interconnect port, of course. Yes, it would HAVE TO have a fill/evac port in order to use an alternate gas. You knew that though. And you could level 3 hard anodize it to stop the surface incursion.
How it can get in, but then not back out is weird though (reference to the diving watch).
The reason they use it is because it has a smaller atom/molecule size, so the heads float closer on a tighter knit blanket of a single element.
Regular hard drives have normal 'air', which is a mix and makes for a less precise head float condition. They are open to and operate at their surrounding standard air pressure. I wonder how well they work at high altitude without cabin pressure compensation. They probably crash more often.
But sealed cans, regardless of the gas media placed in them, would always have the same 'ride' for each given media. And the pressure can be set specifically in sealed environs.
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