Start with the application.
FKM is often shortlisted for oil exposure at elevated temperatures. Chemical resistance varies between FKM families; a polymer name alone does not establish compatibility.
FKM and Viton™ O-rings
Viton™ is a trade name used for certain fluoroelastomers. FKM is the polymer-family designation. If a specific branded grade is required, name it in the enquiry and request supporting compound documentation.
What to verify
Check the exact chemical, concentration and low-temperature requirements. Hot water, steam and certain chemicals require particular care. Obtain a compound-specific assessment.
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.