O-Ring Size Guide
O-Ring Size and Drawing Guide
Prepare the dimensions needed for an O-ring review. Record the inside diameter, cross-section, groove and mating-part dimensions together with the service conditions.
01 / O-Ring Size Guide
Identify dimensions and the size reference
Record the inside diameter (ID) and circular cross-section diameter (CS), with units and tolerances. If the drawing uses ISO 3601-1 or SAE AS568, include the complete size designation and specified edition. If the series is unknown, send the drawing or original reference and the measured sample information for review.
02 / O-Ring Size Guide
Keep the part and installation dimensions together
A replacement request needs the size reference and the geometry where the seal works.
| Input | Information to provide |
|---|---|
| Identity | Part reference, drawing revision and size designation if known |
| Units and dimensions | ID, CS, units, tolerances and measurement method |
| Sample state | New or used, free or installed, damage and available reference sample |
| Groove and mating parts | Groove dimensions, mating diameter, gap and tolerances |
| Installation | Stretch, compression direction, assembly and static or moving duty |
| Material | Specified compound, hardness scale and material requirements |
| Service | Actual media, temperature, pressure history and quantity |
03 / O-Ring Size Guide
Read a simple dimensional example
For an undeformed circular O-ring, the nominal outside diameter is ID + 2 × CS. An illustrative ID of 20.0 mm and CS of 2.0 mm gives 24.0 mm outside diameter. These are assumed dimensions to explain the notation; they do not identify a standard size code, tolerance or approved groove.
04 / O-Ring Size Guide
Review the groove and material separately
Confirm the installed geometry using the actual drawing limits, including compression, stretch and clearance. Keep material selection separate from size identification: a metric dimension or dash number does not specify a compound or brand. A used sample may need comparison with the original drawing before dimensions are agreed.
05 / O-Ring Size Guide
Send the specification for review
Include the drawing, size reference, material, quantity and acceptance requirements. Agree sample inspection and assembly evaluation before adopting a replacement. Where dimensions or the reference series are missing, mark them as unknown and identify who will confirm them.
From your requirements to a component review
Discuss the Specification
Send your drawing or describe the application. Include service conditions, material requirements and quantity.