Am I in the right place? A student looking for a second opinion on O-ring vacuum seal for a project

[Wasara]

Hello, I am an aspiring, young engineer who is currently applying to colleges . My father and I have been building a cyclotron to get a feel for the field and because I have an interest the subject matter. Getting to the point, the vacuum chamber the ions will be propelled in will be sealed with a butyl O-ring on the top and bottom. I have dimensions I have made myself from tables and information I have found online; I just want a second opinion because if the seal fails, I will have probably have to scrap the whole project.

Before I get into the specifics, I want to make sure I'm not in the wrong place. This seems to be a place for professionals, but there are options for students in the sign-up. Since I'm not asking for thesis and homework help, I don't think I am breaking any rules with this post. However, I apologize if I am making a mistake.

If I am in the right place, I will post the O-ring CS and diameters, the dimensions of the O-ring groove, and my attempt at plotting it out on AutoCAD. (This is mostly because I have it written down at my dad's building and I don't have all of the stuff with me right now)

Thank you for taking the time to read what I have to say and any advice would be vastly helpful.

 

[btrueblood]

Get a copy of the Parker Oring Handbook, usually easy to find via a google search, though it may take awhile to download a .pdf file. Butyl sounds like the correct material to use.

 

[Wasara]

Since I got the groove dimensions from the Parker handbook, I'm gonna assume those are right then.
The core concerns I have is that most images of O-ring seals have the O-ring wrapped around the cylinder. The design I have places the O-ring on top of the cylinder. Is this problematic?

 

[btrueblood]

"On top of the cylinder" = the end of the cylinder, i.e. flat face?

Look in the handbook section for face seals, and follow the guidelines.

If you mean on the cylindrical outer surface, well...that could get tricky, but it's still all about matching the two part geometries to get good squish on the o-ring, and preventing more than a few thousandths of inch of gap from forming.

 

[dgallup]

You are in the right place.

Since you are sealing vacuum there are a few special considerations. For one, you don't have to worry about extrusion as there is not enough pressure differential to cause extrusion. You want to be extra careful about surface finish. Make sure you use a material that has low permeability and that won't out gas. There is a special grease used to lubricate o-rings for vacuum applications. Parker may have some more tips or I'm sure you can google it.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[ehbadger]

In addition to the popular Parkers, a google search for the following pdf might prove helpful as well:
ERIKS Sealing Elements Technical Handbook O-Rings

Good luck with the project!

 

[Wasara]

Since the O-ring seal design is mostly to the specifications of the Parker manual, I'm gonna assume I'm well off and probably worrying about it too much.
Thank you for all the tips and special things to also consider. I'm glad I was able to get help.