How do you size orings correctly?

[jmccalip]

I'm making pistons of various sizes and I want to know if there is any sort of chart that tells what size o-ring should go with what size groove. I don't want to waste money on o-rings that are either too loose or too tight. Thanks

[Pilgrimman]

There is a formula on the wiki under the O-ring article, let me find it...

EDIT: Here... http://www.spudfiles.com/spud_wiki/index.php/O-ring

[jmccalip]

There is a formula on the wiki under the O-ring article, let me find it...

EDIT: Here... http://www.spudfiles.com/spud_wiki/index.php/O-ring

This depth can determined by the formula O*(100%-S%) - 1/2(OD - ID) Where O is O-ring thickness, S% is the percent of squeeze (higher percents make tighter O-ring seals), OD is the outside diameter of the interior part, and ID is the inside diameter of the exterior sleeve.

OK, but how do I know what percent of 'squeeze' to use?

[jonnyboy]

It says 5-10 percent

[jmccalip]

It says 5-10 percent

:dontknow:

Thanks, I must be half blind.

[Gippeto]

Here you go, my favorite o-ring literature.

http://www.hitechseals.com/pdf/oringbrochure.pdf

[cdheller]

Parker Hannifin has a free design programs for this.
http://www.parker.com/portal/site/PARKE ... mt=default

""Parker inPHorm for O-Rings is capable of dimensioning an appropriate O-ring gland or groove for Static, Dynamic or Face Seal O-ring applications and recommending the O-ring size to function properly in the recommended groove dimensions. In addition to the complete range of Parker 2-dash O-ring sizes which correspond to the AS568A sizes, Parker 3-dash O-ring sizes for tube fitting bosses are also included. Several of the most time-consuming functions involved in properly calculating O-ring size have been automated with the Parker inPHorm for O-Rings program. Proper O-ring squeeze, installation stretch and gland fill are all calculated as part of the O-ring size portion of the software.
When a seal design has been completed to the user's satisfaction, Parker inPHorm for O-Rings can identify and save the file for future use, and also print out a summary of the finished gland design and material recommendation. A purchase requisition form or Request For Quote (RFQ) for use by procurement personnel may also be printed.
Additional inPHorm Features

Parker inPHorm for O-Rings has two additional features which will be helpful to the user. First, over 95% of the technical content of the current Parker Catalog, ORD5700, O-RING DESIGN HANDBOOK has been included in the inPHorm program. This extensive reference material may be accessed by the user utilizing a convenient pull-down HELP menu. Data may be printed out if desired for reference. Additionally, a complete GLOSSARY of elastomer and sealing terminology is available, also accessible through the HELP menu.""