O-ring design choices

[BtoVin83]

Rule of thumb is that o-rings can be stretched 10%, keep in mind when they do the cross section (hence the depth of the groove) is smaller. Always made mine with perpendicular sides.

 

[Downunder Bob]

The Parker o-ring handbook (which you can download from their website) has lots of good information on o-ring gland design and dimensions for various pressures and sealing scenarios. Start there and adjust the diameters if necessary. There are also lots of odd size o-rings besides the standard 2-xxx sizes, all listed in the handbook appendices.

I totally agree The parker o-ring handbook is the bible of o-rings and will tell you everything you need to know. If you're running in a vacuum get some good, as in parker o-ring lubricant, All dynamic o-ring seals need some lubrication. Also depending on how high your vacuum is o-rings can out gas, some compounds are more resistant than others, the handbook will tell you all this.