Last 2 cents worth of comment….someone is always trying to make good into perfect by making it more complex. Often simple is sufficient and complex only adds cost. Somewhere between drafting board and production lie test and development. Some good ideas really are good and some need more work.
Bearings, seals, fasteners and O rings are STANDARDIZED, designers and engineers use off the shelf items due to HIGH cost of limited production specialty items. O rings are likely to be Metric and Inch stands. Anything made in USA prior to late 1970s will almost certainly be Inch standard. As with bearings, seals and fasteners, O ring makers had to make their standards known and widely available to designers and engineers. Somewhere on the iuternet there will be much more than you want or need to know about O rings…including how to determine size of the O ring you need to replace. Headache Yes, Impossible No.
Louis
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