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Pneumatic Seal Selection, Profiles, and Sourcing
Quick Answer: A pneumatic seal contains compressed air and controls leakage in pneumatic cylinders, valves, actuators, and air tools. CORASEALS supplies pneumatic piston seals, rod seals, wiper seals, O-rings, and wear rings in NBR, polyurethane, FKM, and HNBR. Send the cylinder bore, rod diameter, groove dimensions, operating pressure, temperature, air quality, and a sample photo or drawing to get a quote.
Pneumatic seals may look similar to hydraulic seals, but air service is different. Standard pneumatic cylinders operate in a lower pressure range than hydraulic cylinders. Many circuits run between 0.4 MPa and 0.8 MPa. Some industrial systems reach 1.0 MPa to 1.6 MPa. Compressed air is a thin fluid with little lubrication unless an oil mist is present. Friction, wear, seal geometry, and surface finish must be matched to air service. A hydraulic seal profile that works well in oil may not work well in a dry or lightly lubricated pneumatic cylinder.
Pneumatic Seal Types CORASEALS Can Supply
CORASEALS supplies seals for standard and special pneumatic cylinders. The product range includes:
- Pneumatic piston seals
- Pneumatic rod seals
- Pneumatic wiper seals
- O-rings for static and dynamic sealing
- Wear rings and guide rings
- Cushion seals for cylinder end positions
Piston seals use air pressure to drive the cylinder. Rod seals control leakage at the cylinder rod. Wiper seals prevent dust and particles from entering the cylinder. Wear rings support side load and reduce metal contact between the piston and cylinder bore.
Material Selection for Pneumatic Seals
Material selection depends on temperature, air quality, oil mist, wear, and cycle life. Hardness selection matters. O-ring seals are commonly 70 Shore A. Pneumatic polyurethane rod and piston seals are commonly 90 to 95 Shore A. The table below lists common pneumatic sealing materials as a general reference. Confirm the exact grade with the supplier because fillers and hardness change the limits.
| Material | Common Pneumatic Use | General Temperature Range |
|---|---|---|
| NBR | O-rings, static seals, general air service | -30°C to +100°C |
| Polyurethane | Rod seals, piston seals, wiper seals, high wear | -20°C to +80°C |
| FKM | High temperature air, aggressive media, valve seals | -20°C to +200°C |
| HNBR | Air with oil mist, heat and ozone resistance | -30°C to +150°C |
Polyurethane is common for dynamic pneumatic seals because it resists wear and extrusion. NBR is common for O-rings and static seals. FKM is selected when temperature or chemical resistance is more important than low-temperature flexibility.
Dimensions and Profiles
Pneumatic seals are supplied in metric and inch sizes. CORASEALS does not rely only on type codes because the same code may describe different profiles in different catalogues. The most reliable way to match a pneumatic seal is to provide:
- Cylinder bore diameter
- Rod diameter
- Groove diameter, width, and depth
- Seal ID, OD, and width
- Existing seal drawing or sample photo
If the seal is worn or damaged, measure the groove instead of the old seal. An old seal can swell, shrink, or take a set. The groove is usually the better reference for correct replacement.
Common Failure Causes in Pneumatic Seals
Pneumatic seal failures are often linked to installation, contamination, or operating conditions. Check the following causes before replacing the seal:
- Extrusion from excess clearance or high cylinder pressure
- Wear from dry air, high speed, or high cy