For as568 o-rings (inch series) in Silicone (VMQ), the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for Silicone (VMQ) (vinyl-methyl silicone, typically 70 Shore A) is summarized below together with every size supplied.
Why Choose Silicone (VMQ) for AS568 O-Rings (Inch Series)
Used for wide temperature range and food/medical contact, in static seals only. For as568 o-rings (inch series), this matters when inert and physiologically neutral; low tear and abrasion strength is the primary requirement.
Mechanical & Physical Properties
| Grade designation | vinyl-methyl silicone, typically 70 Shore A |
|---|---|
| Magnetic response | Non-magnetic |
| Service temperature | approx. -60 °C to +200 °C |
| Corrosion characteristic | Inert and physiologically neutral; low tear and abrasion strength |
Corrosion Behavior in Service
Carbon and alloy steel as568 o-rings (inch series) require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Galvanic & Galling Considerations
Galvanic and galling behavior do not apply to as568 o-rings (inch series) in Silicone (VMQ) — the relevant compatibility questions are chemical: confirm the elastomer against the fluid, the temperature and any cleaning agents in service, and check the gland or groove dimensions give the intended compression on the section.
Sizes of AS568 O-Rings (Inch Series) Available in Silicone (VMQ)
| Dash number | Inner diameter d1 (in) | Inner diameter d1 (mm) | Cross section CS (in) | Cross section CS (mm) | Groove width (mm) | Reference standard |
|---|---|---|---|---|---|---|
| AS568-001 | 0.029 | 0.74 | 0.040 | 1.02 | 1.42 | AS 568 |
| AS568-002 | 0.042 | 1.07 | 0.040 | 1.02 | 1.42 | AS 568 |
| AS568-003 | 0.056 | 1.42 | 0.040 | 1.02 | 1.42 | AS 568 |
| AS568-004 | 0.070 | 1.78 | 0.040 | 1.02 | 1.42 | AS 568 |
| AS568-005 | 0.101 | 2.57 | 0.040 | 1.02 | 1.42 | AS 568 |
| AS568-006 | 0.114 | 2.90 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-007 | 0.145 | 3.68 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-008 | 0.176 | 4.47 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-009 | 0.208 | 5.28 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-010 | 0.239 | 6.07 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-011 | 0.301 | 7.65 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-012 | 0.364 | 9.25 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-013 | 0.426 | 10.82 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-014 | 0.489 | 12.42 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-015 | 0.551 | 14.00 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-016 | 0.614 | 15.60 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-017 | 0.676 | 17.17 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-018 | 0.739 | 18.77 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-019 | 0.801 | 20.35 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-020 | 0.864 | 21.95 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-021 | 0.926 | 23.52 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-022 | 0.989 | 25.12 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-023 | 1.051 | 26.70 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-024 | 1.114 | 28.30 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-025 | 1.176 | 29.87 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-026 | 1.239 | 31.47 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-027 | 1.301 | 33.05 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-028 | 1.364 | 34.65 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-029 | 1.489 | 37.82 | 0.070 | 1.78 | 2.49 | AS 568 |
| AS568-030 | 1.614 | 41.00 | 0.070 | 1.78 | 2.49 | AS 568 |


