Start with the application.
Nitrile is commonly considered where a seal is exposed to mineral oils. Compatibility changes with the specific compound and the fluid formulation. Record the actual fluid name rather than simply specifying “oil”.
What to verify
Check fuel formulation, operating temperature and ozone exposure. Outdoor weathering, ozone and a wider temperature requirement may call for another compound.
Specify more than the polymer
Record dimensions, compound identification, hardness, tolerances, working conditions and quantity. Ask for a grade-specific datasheet before design approval.
General polymer guidance is not a guaranteed rating for a finished O-ring. Validate performance in the intended assembly.
Dimensions and standards
Give the inside diameter and cross-section with units. If using a standard size, include its exact designation and applicable revision. Confirm dimensional tolerances against your drawing.
Technical references
General background: Parker O-Ring Handbook and Trelleborg elastomeric O-rings. These references do not certify Rubrings products or establish any affiliation.