Hdd breather holes

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Orange Marmelade

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Anyone with extensive hdd knowledge? I need to know how a hdd 'breathes'. All hdd's have these breather holes to equalize pressure inside to outer.

Once a hdd spins up, is it true it sucks in surrounding air?

And during operation will this initial air be conrinuesly refreshed with new air from outside the hdd, or will the initial aur just tay there ?
 
Spinning hard disks are SEALED AIRTIGHT. There is no breathing at all. That would introduce dust and that is a very bad thing for a platter drive.
 
That is news to me. I am having drinks with a Netapp engineer and he says that yes in fact there is a breather system with a filtration system as well. Learn something everyday. :)
 
to be fair they are sealed air tight, but the seal does release to equalize pressure during use.

They need to be sealed while off to prevent moisture from getting inside.
 
Orange Marmelade said:
Anyone with extensive hdd knowledge? I need to know how a hdd 'breathes'. All hdd's have these breather holes to equalize pressure inside to outer.

Once a hdd spins up, is it true it sucks in surrounding air?

And during operation will this initial air be conrinuesly refreshed with new air from outside the hdd, or will the initial aur just tay there ?
Click to expand...

There is practically no air movement in/out of the drive.
The breathers are for slow temperature related pressure changes and will equalise atmospheric pressure to some degree depending on the hole design.
They have a dense/fine mesh that stop fine particulates making it through.

Turbulence within the drive remains local in the drive, it doesnt make it out of the breathers.
 
I can swear i always feel air movement around a hdd that's sitting naked on my table. My wd elements drive (a hdd inside plastic shell) typically has ventilation around one side of this shell going all the way to top. If it is operational. I can drfinitely feel air movement from this vent side of the plastic shell causing all kinds of turbulence. Don't know what could account for that. Must be my imagination..
 
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Trimlock said:
to be fair they are sealed air tight, but the seal does release to equalize pressure during use.

They need to be sealed while off to prevent moisture from getting inside.
Click to expand...

That explanation does not make sense. I don't know whether you are right or wrong about them having an airtight seal when powered off which opens when powered on, but if you are right, then that does NOT explain anything about water vapor passing through the breather hole.

This seems obvious, but in case you need an example, consider a drive that is used (i.e., powered on) in Denver, where the air pressure is relatively low. Then the drive is powered off and shipped to a humid location near the equator and near sea level (where air pressure is higher). If the drive is then powered on and this seal you talk about opened, then the humid air (at higher pressure than the air in the drive) would pass into the breather hole.

My guess is that the breather hole has a membrane that is impermeable to water vapor and/or the inside of the drive has a desiccant material or coating to absorb moisture.

As for whether the drive is sealed air-tight when powered off, I tend to doubt it, but as I said before, I don't know. The reason I doubt it is because I don't think the walls of standard (i.e., not He-sealed) drives are strong enough to withstand pressure differences if the drive is shipped to an area with significantly different air pressure than where it was last powered on.
 
JoeComp said:
That explanation does not make sense. I don't know whether you are right or wrong about them having an airtight seal when powered off which opens when powered on, but if you are right, then that does NOT explain anything about water vapor passing through the breather hole.

This seems obvious, but in case you need an example, consider a drive that is used (i.e., powered on) in Denver, where the air pressure is relatively low. Then the drive is powered off and shipped to a humid location near the equator and near sea level (where air pressure is higher). If the drive is then powered on and this seal you talk about opened, then the humid air (at higher pressure than the air in the drive) would pass into the breather hole.

My guess is that the breather hole has a membrane that is impermeable to water vapor and/or the inside of the drive has a desiccant material or coating to absorb moisture.

As for whether the drive is sealed air-tight when powered off, I tend to doubt it, but as I said before, I don't know. The reason I doubt it is because I don't think the walls of standard (i.e., not He-sealed) drives are strong enough to withstand pressure differences if the drive is shipped to an area with significantly different air pressure than where it was last powered on.
Click to expand...

No mine was just an overly simplified response. There's documentation on the holes, they are pretty complicated to explain.
 
Imagine that the hole has a rubber sheet with a pin prick in it.
 
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