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Suggested Groove Design for PTFE O-Rings

Grooves for PTFE O-Rings are similar to those for rubber O-Rings, except that less squeeze is applied due to the relative stiffness of the material. Also, the groove width is generally less, as PTFE O-rings are much less likely to roll in reciprocating applications than their elastomeric counterparts. A surface finish of 16 rms or less is ideal, although rougher surfaces are acceptable if a shorter seal life can be tolerated. A radius of .005” on the groove corners is advisable.

AS568 O-Ring No. Nominal ID Range Cross-Section Min. Squeeze Groove Width
004 thru 048 5/64" to 4-3/4" .070" ± .003" .005" .080"
106 thru 157 3/16" to 4-1/2" .103" ± .003" .006" .110"
204 thru 248 3/8" to 4-3/4" .139" ± .004" .007" .160"
320 thru 350 1-1/8" to 4-5/8" .210" ± .005" .008" .240"
425 thru 441 4-1/2" to 7" .275" ± .006" .010" .315"