A toroidal (doughnut-shaped) mechanical seal designed to sit in a gland or groove and create a leak-proof barrier between two mating surfaces when compressed.
Common Materials & Grades:
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Nitrile (Buna-N): General-purpose; good resistance to oils, fuels and water.
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EPDM (Ethylene-Propylene): Excellent for steam, hot water and brake fluids; poor petroleum resistance.
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Viton® (FKM): High temperature and aggressive-chemical resistance.
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Silicone: Wide temperature range; very flexible but lower mechanical strength.
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PTFE (Teflon®): Exceptional chemical inertness; stiffer, often used as back-up or on its own in specialised applications.
Key Characteristics to Consider:
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Size (ID × CS): Inside diameter and cross-section must match the groove dimensions exactly.
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Hardness (Shore A): Typically 50–90 Shore A; softer compounds conform better to rough surfaces, harder grades resist extrusion under pressure.
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Temperature Range: Varies by material (e.g. –55 °C to +200 °C for nitrile; –60 °C to +250 °C for Viton®).
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Chemical Compatibility: Select material based on exposure to oils, solvents, acids or alkalis.
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Static vs Dynamic Use: Static seals (stationary parts) can tolerate different tolerances than dynamic seals (rotating or reciprocating shafts).
Typical Applications:
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Hydraulic and pneumatic cylinders
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Valve and pump housings
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Pipe and flange connections
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Automotive engine seals (oil, coolant)
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Food- and medical-grade equipment (with FDA-approved materials)
