Pneumatic Cylinder O-Rings
Low-friction, fast-response sealing for compressed air cylinders, valves and fittings.
Pneumatic systems operate at lower pressures than hydraulics but demand seals with very low friction, fast response, and resistance to dry running. O-rings in pneumatic cylinders must seal compressed air without sticking or causing jerkiness in cylinder motion. NBR 70 Shore A is the most common choice for general pneumatic service due to its low cost, good air sealing properties, and compatibility with standard pneumatic lubricants. For unlubricated or high-cycle systems, polyurethane (PU) offers superior abrasion resistance and lower dynamic friction. FKM is specified for high-temperature pneumatic systems near heat sources.
Application Requirements
Recommended Materials
Design Tips
- 1.Use 70 Shore A NBR for the lowest friction in standard pneumatic cylinders
- 2.Keep compression at 10-15% for dynamic pneumatic seals to minimise stick-slip
- 3.Specify polyurethane for unlubricated or high-speed applications above 0.5 m/s
- 4.Use generously radiused groove corners to prevent pinching during fast cycling
- 5.Consider X-Rings (Quad Rings) for bi-directional double-acting pneumatic cylinders
Common Sizes
| Size | Typical Use |
|---|---|
| AS568-010 to AS568-050 | small bore compact cylinders |
| AS568-110 to AS568-178 | standard ISO 15552 pneumatic cylinders |
| AS568-210 to AS568-284 | large bore and rodless cylinders |
| Metric ISO 3601 sizes for European pneumatic equipment | General application |
Frequently Asked Questions
What is the best O-ring material for pneumatic cylinders?
NBR 70 Shore A is the standard choice for lubricated pneumatic cylinders. Polyurethane is better for unlubricated or high-wear applications.
Can I use hydraulic O-rings in pneumatic cylinders?
Yes, but pneumatic seals generally require lower compression (10-15%) than hydraulic seals to reduce friction and prevent stick-slip motion.
Why does my pneumatic cylinder jerk or stick?
Stick-slip is usually caused by too much compression, incompatible lubrication, or a seal material with too high friction. Reduce compression, check lubricant compatibility, or switch to a lower-friction material.
Are X-Rings good for pneumatic cylinders?
Yes. X-Rings reduce friction and resist spiral failure, making them an excellent upgrade for reciprocating pneumatic cylinder seals.
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