Rotating shaft seal for keeping the sea water out at 10m depth

Your life expectancy is reasonably short. I would investigate the type of seals used in gas spring applications. Pressurize you container to high pressure if possible and use the seal to keep the gas in. The gas pressure will keep the water out.

You'll need to find one without exposed metal backing.

They aren't designed for rotation but your surface speeds are very low so you'll likely be able to get away with it.

Here's a sketch for a dual O-ring seal and a sleeve bearing. Is this a sensible approach?

Is there a reason you insist on o-rings over lip seals?

TugboatEng said:

Is there a reason you insist on o-rings over lip seals?

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I drew O-rings only because they seem to be easier for me to find. I'm not insisting on O-rings for fundamental technical reasons. Nor am I attached to O-rings emotionally.

Lip seals would be fine. I’m in the US, and I should have first world access to parts. But I have a hard time finding lip seals for 6mm [0.25 inch] shaft diameters or smaller.

I looked into your link to the SKF gas spring seals. There are small gas springs with my kind of shaft diameters, so there should be small enough gas spring seals. But I couldn’t find the SKF’s catalog with their standard sizes. I’ve e-mailed them, but haven’t heard back from them. Maybe they aren’t interested in working with me, because I’m not a high volume customer.

Meanwhile, the classic Parker Hannifin text on O-rings has a chapter on dynamic applications. That’s how I’ve defaulted to O-rings.

Manufacturers don't typically maintain a sales team and work through local distributors. Always check the manufacturer's website for a list of distributors. Bearing Engineering Co. is my local distributor.

Bearing Egineering is local for me too (you and I must be both living in Northern California). They said that they can provide any SKF part if I give them part number or dimensions. Do you know how to look-up part numbers for the SKF's gas spring seals? Their brochure doesn't have part numbers or sizes. Does SKF have a size table somewhere? Are there industry-standard sizes, and SKF makes those sizes?

Hmm, I was hoping they would be more helpful.

The Chicago Rawhide catalog is here but it doesn't have any profiles that I think would be appropriate.


You need a fully rubberized seal without garter spring, you don't want to be buying inconel springs.

The HM1 profile would be acceptable for your application if lipped for outwards pressure. They are available in 4.78 and 7.95mm shaft diameter... odd.

I haven't drawn-up a variant with the HM1 profile, yet. I was drawing a variant with a different kind of lip seal which I found on McMaster: seal, sleeve bearing.

What do you think?

TugboatEng said:

Hmm, I was hoping they would be more helpful.

Click to expand...

Maybe it varies from one location to another. I was calling their warehouse in SF.

TugboatEng said:

They are available in 4.78 and 7.95mm shaft diameter... odd.

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I suspect that's 3/16 and 5/16 inch.