Resources
O-ring size chart
AS-568A and ISO 3601-1 dimensions, ungated and searchable. When a standard size does not fit your groove, we mould to your drawing.
AS-568A
| Dash | ID (in) | ID (mm) | CS (in) | CS (mm) | ISO 3601 |
|---|---|---|---|---|---|
| -001 | 0.070 | 1.78 | 0.013 | 0.33 | 3 |
| -002 | 0.110 | 2.79 | 0.021 | 0.53 | 4 |
| -003 | 0.130 | 3.30 | 0.025 | 0.64 | 5 |
| -004 | 0.150 | 3.81 | 0.026 | 0.65 | 6 |
| -005 | 0.170 | 4.32 | 0.026 | 0.65 | 7 |
| -006 | 0.180 | 4.57 | 0.028 | 0.71 | 8 |
| -007 | 0.195 | 4.95 | 0.028 | 0.71 | 9 |
| -008 | 0.220 | 5.59 | 0.028 | 0.71 | 10 |
| -009 | 0.234 | 5.94 | 0.033 | 0.84 | 11 |
| -010 | 0.255 | 6.48 | 0.033 | 0.84 | 12 |
| -011 | 0.275 | 6.99 | 0.033 | 0.84 | 13 |
| -012 | 0.295 | 7.49 | 0.037 | 0.94 | 14 |
| -013 | 0.315 | 8.00 | 0.037 | 0.94 | 15 |
| -014 | 0.335 | 8.51 | 0.037 | 0.94 | 16 |
| -015 | 0.355 | 9.02 | 0.037 | 0.94 | 17 |
| -016 | 0.375 | 9.53 | 0.037 | 0.94 | 18 |
| -017 | 0.395 | 10.03 | 0.037 | 0.94 | 19 |
| -018 | 0.425 | 10.80 | 0.050 | 1.27 | 20 |
| -019 | 0.445 | 11.30 | 0.050 | 1.27 | 21 |
| -020 | 0.475 | 12.07 | 0.050 | 1.27 | 22 |
| -021 | 0.495 | 12.57 | 0.050 | 1.27 | 23 |
| -022 | 0.520 | 13.21 | 0.050 | 1.27 | 24 |
| -023 | 0.545 | 13.84 | 0.050 | 1.27 | 25 |
| -024 | 0.575 | 14.61 | 0.050 | 1.27 | 26 |
| -025 | 0.595 | 15.11 | 0.050 | 1.27 | 27 |
| -026 | 0.620 | 15.75 | 0.050 | 1.27 | 28 |
| -027 | 0.675 | 17.15 | 0.062 | 1.57 | 29 |
| -028 | 0.700 | 17.78 | 0.062 | 1.57 | 30 |
| -029 | 0.735 | 18.67 | 0.062 | 1.57 | 31 |
| -030 | 0.765 | 19.43 | 0.062 | 1.57 | 32 |
| -031 | 0.795 | 20.19 | 0.062 | 1.57 | 33 |
| -032 | 0.830 | 21.08 | 0.062 | 1.57 | 34 |
| -033 | 0.860 | 21.84 | 0.062 | 1.57 | 35 |
| -034 | 0.890 | 22.61 | 0.062 | 1.57 | 36 |
| -035 | 0.920 | 23.37 | 0.062 | 1.57 | 37 |
| -036 | 0.940 | 23.87 | 0.062 | 1.57 | 38 |
| -037 | 0.970 | 24.64 | 0.062 | 1.57 | 39 |
| -038 | 1.000 | 25.40 | 0.062 | 1.57 | 40 |
| -039 | 1.030 | 26.16 | 0.062 | 1.57 | 41 |
| -040 | 1.060 | 26.92 | 0.062 | 1.57 | 42 |
| -041 | 1.110 | 28.83 | 0.062 | 1.57 | 43 |
| -042 | 1.140 | 28.96 | 0.062 | 1.57 | 44 |
| -043 | 1.170 | 29.72 | 0.062 | 1.57 | 45 |
| -044 | 1.200 | 30.48 | 0.062 | 1.57 | 46 |
| -045 | 1.230 | 31.24 | 0.062 | 1.57 | 47 |
| -046 | 1.260 | 32.00 | 0.062 | 1.57 | 48 |
| -047 | 1.290 | 32.77 | 0.062 | 1.57 | 49 |
| -048 | 1.320 | 33.53 | 0.062 | 1.57 | 50 |
| -049 | 1.350 | 34.29 | 0.062 | 1.57 | 51 |
| -050 | 1.380 | 35.05 | 0.062 | 1.57 | 52 |
ISO 3601-1
| Code | ID (mm) | CS (mm) |
|---|---|---|
| 3 | 1.8 | 0.33 |
| 4 | 2.8 | 0.53 |
| 5 | 3.3 | 0.64 |
| 6 | 3.8 | 0.65 |
| 7 | 4.3 | 0.65 |
| 8 | 4.6 | 0.71 |
| 9 | 5.0 | 0.71 |
| 10 | 5.6 | 0.71 |
| 11 | 5.9 | 0.84 |
| 12 | 6.5 | 0.84 |
| 13 | 7.0 | 0.84 |
| 14 | 7.5 | 0.94 |
| 15 | 8.0 | 0.94 |
| 16 | 8.5 | 0.94 |
| 17 | 9.0 | 0.94 |
| 18 | 9.5 | 0.94 |
| 19 | 10.0 | 0.94 |
| 20 | 10.8 | 1.27 |
| 21 | 11.3 | 1.27 |
| 22 | 12.1 | 1.27 |
| 23 | 12.6 | 1.27 |
| 24 | 13.2 | 1.27 |
| 25 | 13.8 | 1.27 |
| 26 | 14.6 | 1.27 |
| 27 | 15.7 | 1.27 |
| 28 | 15.9 | 1.27 |
| 29 | 17.2 | 1.57 |
| 30 | 17.8 | 1.57 |
| 31 | 18.7 | 1.57 |
| 32 | 19.4 | 1.57 |
| 33 | 20.2 | 1.57 |
| 34 | 21.1 | 1.57 |
| 35 | 21.8 | 1.57 |
| 36 | 22.6 | 1.57 |
| 37 | 23.4 | 1.57 |
| 38 | 23.9 | 1.57 |
| 39 | 24.6 | 1.57 |
| 40 | 25.4 | 1.57 |
| 41 | 26.2 | 1.57 |
| 42 | 26.9 | 1.57 |
| 43 | 28.8 | 1.57 |
| 44 | 29.0 | 1.57 |
| 45 | 29.7 | 1.57 |
| 46 | 30.5 | 1.57 |
| 47 | 31.2 | 1.57 |
| 48 | 32.0 | 1.57 |
| 49 | 32.8 | 1.57 |
| 50 | 33.5 | 1.57 |
| 51 | 34.3 | 1.57 |
| 52 | 35.0 | 1.57 |
Dimensions follow AS-568A and ISO 3601-1. FFKM is a high-modulus elastomer, so gland design should start from the same squeeze figures as FKM and then be checked against the grade's compression set at the actual service temperature. Sizes outside the ranges listed here are available on request — send a drawing or a part number and we will confirm availability.
Groove design guidance
General elastomeric-sealing engineering conventions, stated so you can judge how they apply to your gland. Grade-specific design values are confirmed per enquiry.
| Parameter | Value | Note |
|---|---|---|
| Squeeze (compression) | 15–30 % | The standard working range for a static radial or axial O-ring seal. FFKM tolerates the upper end better than FKM because of its higher modulus retention at temperature. |
| Gland fill | 70–90 % | Allowance for thermal expansion of the seal and for swell in the process media. A dedicated gland-fill calculation should be made for aggressive media. |
| Extrusion gap | Fit with a back-up ring above the threshold | At high temperature and system pressure, or with a 90 Shore A grade such as OM9090, a back-up ring (commonly PTFE) is generally required to prevent extrusion. |
| Surface finish | Ra ≤ 1.6 µm groove, Ra ≤ 0.8 µm sealing surface | Finish the sealing surface in the direction of extrusion and remove tool marks from the groove floor. |
| Compression set | Specify the test temperature that matches service | Compression set must be quoted at the service temperature, not at a convenient reference. See each grade page for its stated condition. |
Need help selecting an FFKM compound?
Send your operating conditions or a drawing and our engineers will recommend a grade and confirm availability.