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Comment by yummypaint | Hacker News Reader

This seems like a terrible use of helium from a sustainability perspective. There are some things that helium is truly essential for, like low temperature cryogenics and neutron detection. Our supply is finite and largely tied to natural gas reserves. When helium leaks out it floats into space and is gone forever. Why does the atmosphere in the drive absolutely have to be helium? Why not any other mix of inert gases at optimal pressure for a thin air cushion?

Helium is also literally the leakiest thing you can try to contain. It will even diffuse out through the metal itself given enough time. Not trying to go full tinfoil hat here, but filling equipment with helium in this way seems like an effective way to cap drive life by time elapsed rather than amount of actual use.

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The amount used in these drives is minuscule, akin to a single party balloon. Given these drives are to be used for many years at a time, I'll go after them after I manage to stop all the birthday balloons.

Does anyone have a number on how much Helium is produced in the Earth's crust by radioactive decay?

Not enough. It is generally known that we are using helium faster than the planet can naturally produce it. We currently get helium from natural gas deposits. In the future we might end up puling it from the air, but that would be very expensive. For many use cases it might be easier to switch to hydrogen.

For those interested in SETI, excessive atmospheric helium might be a detectable techno-signature, a sign that someone is digging into deep crust presumably for hydrocarbons.

When we use the reserves completely and prices sky rocket, probably unnecessary entertainment use of it would stop.

I am sure we are using it faster than we are extracting it, and it'll be interesting to see what happens when selling hydrocarbons no longer offsets the cost of extracting it, but I was thinking about how much is actually produced.

A party balloon full of helium is a minuscule amount?

Note this is liquid helium in one operational MRI machine:

"Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)."

https://lbnmedical.com/liquid-helium-in-mri-machine/

That is liquid, so for the gas we can multiply 864 by about 1000. So this MRI machine is using 86,000 liters of helium gas per year. That is what, 40,000 party balloons? Say each machine does 1000 scans per year, that is a good-sized cluster of party balloons for every scan. So yes, a single party balloon pales in comparison to the amount of helium being used for MRI scans.

(There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.)

Many modern liquid rocket engine powered space launchers also use quite a lot of helium for tank pressurisation in flight. Helium being inert with very low melting point is ideal for this use case, especially with cryogenic propelants.

With the most modern generation of reusable space launchers such as SpaceX starship an alternative solution is being worked on, possible thanks to both fuel (methane) and oxidizer (oxygen) they use being cryogenic.

Instead of pressurizing with helium they heat up a bit of the cryogenic liquids using the rocket engine heat, let it expand into gas and use it to pressurize the tanks, no helium required!

One of the reasons is that for fully reusable space launchers the main cost is the propelant and helium in the amounts needed would be a big part of that!

In some cases the helium cost is comparable to that of the propellants!

Both are negligible compared to the total cost of space launch currently, but once reusability and operations become more streamlined, they start mattering more.

> "Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)."

I know this is napkin math so it doesn't really matter, but a 4% loss times 12 months would be 1-(.96^12) = 39%. Unless of course they're topping up the helium every month.

I'm not sure that the percentage matters in cooling. This stuff is cooling working parts (magnets). Boiling is therefore related to the amount of heat needing to be absorbed rather than the amount of helium in the tank. A half-empty machine would probably need to boil off just as much helium per time/use/work cycle as a full one.

The other error I now realize is that these HDDs probably have much less helium than any party balloon. They appear to be below atmospheric pressure and are so small that they are probably less than a tenth of a liter each. So one MRI scan is probably the equivalent of hundreds of these HDDs.

Superconducting magnets don't produce heat. (They are superconducting) All the heat comes from the resistive feeder cables and the walls of the cryostat.

Loses a percentage of its capacity, not a percentage of the amount of helium it has.

Thanks, this thread just made “number of party balloons” my new favorite unit of measure

balloon gas is typically about 90% helium and is generally a recycling of helium expended in industrial applications.

> (There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.)

For the purpose of worrying about future supply, we probably want to compare to those. A balloon is a tiny waste compared to an MRI that vents helium willy-nilly, but it's a much larger waste compared to an MRI that gives half a care.

Just use hydrogen for the party balloons

That'd be an exciting party!

Backblaze did a blog post about helium drives in 2018:

https://www.backblaze.com/blog/helium-filled-hard-drive-fail...

Some interesting stuff in there, like the SMART data element for helium status. And this quote, after they had 3 years in with helium drives:

"To date only one HGST drive has reported a value of less than 100, with multiple readings between 94 and 99."

But, then, later, this quote:

"My prediction is that the helium drives will eventually prove to have a lower AFR. Why? Drive Days."

Would be cool if a Backblaze employee could chime in with what they've seen since.

>Would be cool if a Backblaze employee could chime in with what they've seen since.

can't you check their follow-up reports they've posted? I believe that they break out AFR numbers by drive model so it shouldn't be too hard to separate out the helium drives from the normal drives.

> Not trying to go full tinfoil hat here, but filling equipment with helium in this way seems like an effective way to cap drive life by time elapsed rather than amount of actual use.

Recognizing planned obsolescence is not tinfoil hat territory. It's a rational and predictable commercial practice equivalent to rent-seeking, you're not crazy.

Hard disk drives are a commodity component and the main buyers of He nearline drives are the most sophisticated companies in the world. It’s not a trick dude.

Thought i would expand on this with some order of magnitude leak rate guesses. For a standard small lab vacuum system with viton o-rings something like 10-7 mbarliters/sec (same as atmcc/sec) would be considered acceptable. Assuming the drive is pure helium at half pressure with this leak, the loss would be on the scale of 3 cc/year. The rate will decrease as the partial pressure decreases, but once this becomes significant im guessing the drive is already toast.

I would also note that the helium will leak out before atmosphere leaks in. If the drives are well sealed they should fail due to lack of pressure causing head crash.

I think helium is used for its low kinematic viscosity. That lets the R/W head fly closer than, for example, air. The other inert gases (Ar, Ne, etc.) have KV values higher than air and would give no advantage. He is better for thermal reasons, too.

Counterpoint: new large markets & high tech applications for helium will drive up the price. At this point consumers might scale back the balloons.

Wow you should definitely reach out to the thousands of career hard disk engineers to inform them of your idea using different inert gases. They probably haven’t considered that one.

Tbh I would like to see some calculations of how much helium there is in the drive, a quick bit of napkin math makes it seem like you can make around 5*10^10 drives with the gas from a single field in the US on a single day, assuming that it is at 1 atm pressure, though I don't think that would move much more than one order of magnitude at most. Though your other point still stands.

Note that right now we're burning the natural gas either way. How much of the helium we get out depends upon market use of natural gas, and market prices about whether we even bother to capture the helium from natural gas supplies that are rich in helium.

What gas would you recommend and how does it compare? This would be easy to settle using data.

my first thought was what happens when it leaks out?

Sounds like planned obsolescence.

This class of drive will typically have a design life of 5yrs at 100% duty.

100% duty cycle on the spindle motors, perhaps. But they're definitely not rated for actively performing IO 100% of the time.

It’s not planned obsolescence to include Helium when the medium requires it. If you want 18 TB, you’re going to need Helium (from what I know), but if you want less, you might not get it. Planned obsolescence is about planning (hence the name) to make a device worse to encourage upgrading. The device going bad after a while simply by its nature just makes the obsolescence aspect an added benefit.

Is it planned obsolescence that alkaline batteries go bad if left unused for a while? That moving parts in a car can wear out? I wouldn’t say it is.

If the internal pressure in the device is lower than one atm, the leakage is easier to contain because it's not helium wanting to go out, but air pushing to come in.

Eventually it will happen and the internal drive atmosphere will be compromised to a point it doesn't work anymore. By then, it should be safe enough to open the drive in a clean Helium-filled room and reseal it.

Or just read the data, store it someplace more durable, and put the drive in a museum.

So it becomes read only when helium leaks out?

I have no idea. May become unreadable if the head can't read because the disk is too far (or if it's too close and it crashes on the disk)

I though it would just lead to more heat, but reading this[1] from Seagate it seems indeed possible that the drive will not function if too much air gets in:

Furthermore, the use of a higher number of thinner disks is not possible because the windage induces turbulence and makes 7200-RPM tracking impossible at the desired TPIs. The only way to reduce windage in air-filled HDDs is to significantly lower the spindle speed (RPM). However, the largest part of the business-critical market is not willing to accept lower RPMs due to the performance and throughput loss. This means that helium HDD technology is the only viable path forward for delivering higher capacities because it will allow for an increased number of thinner disks.

That said, they also go into the efforts they do to seal the helium, so hopefully the helium stays put...

[1]: https://www.seagate.com/files/www-content/product-content/en...

I'll interpret that as: The drive could be designed with a failsafe lower-RPM mode but it's not worth the engineering budget to allow more than one speed.

Especially looking at WD's "5400 RPM Class" thing as evidence that it takes effort to change the speed of a drive.

I'm no physicist, but I don't think diffusion works that way.

Even if the internal pressure is 1% of a standard atmosphere, if the density of helium inside is higher than the density of helium outside, the helium will still "want" to leave the box.

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