Amir,

Vacuum-rated rotary feed-throughs are off-the-shelf.

MDC Caburn, Kurt Leskar, etc. all the usual culprits have offerings.

For example:

https://www.lesker.com/newweb/sample_manipulation/rotary/menu.cfm

I'd also check eBay and see who is selling a known-to-be-good component.

Hi Amir.

If the pressure difference between the enviroments does not goes beyond 200 [bar] you can use standard O-Rings. This is only possible if modifications for the housing of the O-Ring are allowed.

Cheers.

For small torques, magnetic coupler is simplest solution. Some magnetic stirrers are specifically designed to work through the wall of vacuum/gas chamber. Or place your machine (motor) directly inside vacuum chamber. I still vividly remember the horrors of using shaft and seals. Gas leakage, grease leakage, and finally overheat of seals.

Thanks everyone

I need to transfer torque at 3000 Rpm and 400 hp.

and vacuum inverontment is 20 mbar.

I think that a standard seal is the right choice, since the pressure drop is low and the RPMs and power are high. An example of this use is the sealing of the main shaft on car's motors, which are close to your specifications, and last for years.

But, as I said before, it all depends on the possibility of making a housing.

For 20 millibar, no need to worry about leakages. Therefore, shaft-type coupling will be fine. For 400hp (300kW transferred power) the seals friction power on 5cm shaft is going to be about ~2kW though - take care.

Can use this type of seal for this project?

https://www.youtube.com/watch?v=Yd5z_kHgnv8

Amir,

Yes - a commercial sealing technology can work - but you will have to engineer a housing to hold the sealing ring.

I see two approaches.

1) Make your own feedthrough from commercial seals - it *will* leak, but if you have a big enough vacuum pump, you may be able to overcome the leak rate.

2) Buy/borrow a dedicated feedthrough. A high torque Rigaku is a few hundred USD on eBay (and I fully understand the difficulties you face in buying items like that!).

3) Go and talk to some experimental physicists - you may be surprised what their high-energy and surface-science groups are doing. In the meteoritics department during my PhD, I found an old 0.5m^3 ion probe - complete with rotary feedthroughs - and built a UHV rated drilling system for cryogenic ices.