Foreign material accounts for any contamination present or any indentation left by the removal of a contaminant.
| Specification | Max Allowable Contaminant (or Indentation) Width (inches)** | Max Allowable Contaminant (or Indentation) Depth (inches)** |
|---|---|---|
| AS708* | 0 | 0 |
| ISO 3601-3 CS | .0051 (Indentation after removal) | .0031 |
| AS871 | .003 (Indentation after removal) | .002 (Indentation after removal) |
| ISO 3601-3 S, DIN 3771 S | .0059 | .0031 |
| ISO 3601-3 N, DIN 3771 N | .0236 | .0031 |
| MIL-STD-413C 0 | 0 | 0 |
| RMA OR-1 A | 0 | 0 |
| RMA OR-1 B | .005 | .003 |
The data above shows the maximum allowable width and depth of contaminant/foreign material/indentation assuming an o-ring cross sectional diameter is between 0 and 0.1 inches.
