Key principles.
Per AS568
Standard sizes per AS568 (Aerospace Standard). Groove dimensions per spec.
15-30%
Standard compression 15-30%. Higher = better seal but faster wear.
Ra 0.8-1.6 µm
O-ring contact surface. Smoother prevents leakage but accelerates wear.
Per fluid
NBR oil, EPDM water, Viton fuel, silicone temperature.
Compression-driven
Higher pressure = harder seal. Material strength limits.
Per pressure
Larger cross-section better at high pressure.
FAQ
AS568 aerospace. SAE J120 industrial. Both define O-ring sizes/grooves. Compatible.
NBR: oils, fuels. EPDM: water, weather. Viton: chemicals, high temp. Silicone: extreme temp range.
Static seal: stationary mating. Dynamic seal: rotating/sliding. Different design rules.
Ra 0.8-1.6 µm typical. Smoother seals better but wears faster (dynamic). Per application.
Material recovery from compression. Lower = better seal life. Silicone, Viton best.
NBR cheap. EPDM mid. Viton premium. Silicone mid. Choose per environment.
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