PTFE O-rings are highly specialized sealing components known for their unique combination of physical and chemical properties. They are white in color with a round profile, offering a hardness of 60-65 Shore D, tensile strength of 3625-4496 psi, and elongation of 300-400%. Their standout features include extreme chemical resistance, a high melting point of 327°C (621°F), low friction coefficient, non-stick surface, and excellent electrical insulation. These characteristics make them ideal for demanding applications in chemical processing, high-temperature environments, and situations requiring reliable sealing with minimal friction.
Key Points Explained:
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Color and Profile
- PTFE O-rings are uniformly white, which is characteristic of pure PTFE material.
- They feature a round cross-sectional profile, similar to traditional elastomeric O-rings, but with different material properties.
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Hardness (Durometer)
- Measured at 60-65 Shore D, indicating they are significantly harder than rubber O-rings (which typically measure 70-90 Shore A).
- This hardness contributes to their non-compressibility, requiring precise gland design for effective sealing.
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Mechanical Properties
- Tensile Strength: Ranges from 3625-4496 psi, making them strong but less elastic than rubber alternatives.
- Elongation: 300-400% minimum, allowing some flexibility despite their rigidity compared to elastomers.
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Thermal Properties
- Melting Point: 327°C (621°F), enabling use in high-temperature applications where most elastomers would fail.
- Operating Range: -73°C to 204°C, covering extreme cold and moderate heat. For higher temperatures, ptfe backup rings are often paired with other seals.
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Surface Characteristics
- Low Friction: Coefficient of friction is among the lowest of any solid material (≈0.05-0.10), reducing wear and energy loss.
- Non-Stick: Inherent repellency to adhesives and contaminants, simplifying maintenance.
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Chemical Resistance
- Nearly inert, resisting acids, bases, solvents, and aggressive media. This makes them ideal for chemical processing equipment.
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Electrical Insulation
- Excellent dielectric properties, suitable for sealing in electrical or semiconductor applications.
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Comparison to PTFE-Encapsulated O-Rings
- While solid PTFE O-rings excel in chemical/thermal resistance, encapsulated versions add elasticity by combining PTFE with an elastomer core.
Practical Implications for Purchasers:
- For Static Seals: PTFE O-rings perform well in flange or face seal configurations where movement is minimal.
- Dynamic Applications: Their low friction suits rotating/reciprocating shafts, though supplemental lubrication may be needed.
- Critical Considerations: Gland design must account for PTFE’s cold flow behavior; over-compression can cause deformation.
These properties collectively make PTFE O-rings indispensable in industries like aerospace, pharmaceuticals, and energy, where material stability under stress is paramount.
Summary Table:
| Property | PTFE O-Ring Characteristics |
|---|---|
| Color | White |
| Hardness (Shore D) | 60-65 |
| Tensile Strength | 3625-4496 psi |
| Elongation | 300-400% |
| Melting Point | 327°C (621°F) |
| Operating Range | -73°C to 204°C |
| Friction Coefficient | 0.05-0.10 (extremely low) |
| Chemical Resistance | Resists acids, bases, solvents, and aggressive media |
| Electrical Insulation | Excellent dielectric properties |
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