PTFE O-ring or Teflon O-ring (DuPont’s brand name) is a mechanical gasket that is a gold standard for high-performance sealing solutions. The O-rings are made from different grades of polytetrafluoroethylene whose main elements are fluorine and carbon.
The Teflon O-rings are suitable for applications requiring non-compressible material while offering the highest thermal and chemical resistance.
Ideally, a Teflon O-ring is a circular-shaped gasket, with a wide hole or space at the center. At times, you may find people calling this sealing accessory PTFE packing. However, the name PTFE toric joint is not common.
Wide PTFE O-ring Temperature Range
The working temperature varies between -328°F and 482°F. A good example is cryogenic O-rings. Besides, they have the highest thermal resistance.
Virgin PTFE O-rings are resistant to most solvents or chemical agents. A reason you will find the O-rings in most joints in chemical industries. Only a few alkali and fluorine compounds can affect these O-rings but under special conditions.
PTFE O-ring Pressure Rating
The pressure rating varies with the O-ring’s cross-section area. It varies from low to medium.
Teflon O-ring Compressive Properties
The compressive strength is about 3,500 psi with a load-bearing capacity of about 130 and 140 kg/cm2.
It has the lowest friction coefficient. This makes it a perfect sealing for moving sections.
Different Sizes and Shapes
Looking at PTFE O-ring size chart, you will find many options with varying radial and axial cross-sections. This also affects the internal and external diameters. You can get PTFE large diameter O-ring or small options, depending on the requirements of the application.
The polytetrafluoroethylene O-rings prevent possible leakages. PTFE O-ring flexibility is a contributing factor to its use in either dynamic or static applications.
- Mass spectrometer probes
- Valve systems
- Common in fluid-carrying systems
- Flange connections
- Milling and grinding systems
- Stirring, mixing, or agitator processes
- Blower systems
- Pump systems
- Caps, etc.
It is worth noting that PTFE O-rings are costly. Also, if you are opting for reusing PTFE O-rings, ensure they are in good working condition. Due to the PTFE non-stick property, the O-rings are easy to clean.
|Cross Section (mm)
|1.8mm 2.65mm 3.55mm
|2.65mm 3.55mm 6.3mm 7.0mm
Many Designs Available
You can find both stand and custom Teflon O-ring designs. For instance, there are:
- Round PTFE O-rings
- Rectangular PTFE O-rigs
- Square cut beveled PTFE O-ring
- Expanded PTFE O-ring
Many Color Options
Although virgin PTFE produces whitish O-rings, you can find other color options depending on your custom requirements.
In addition to these, Teflon O-rings have a long service lifespan, will not swell as a result of absorbing moisture, and offer better electrical insulation.
Among the biggest challenges you may experience with an O-ring made of PTFE are:
- High hardness, which may affect the sealing properties
- Compared to elastomeric O-ring, leakages can be high on PTFE
PTFE O-rings Working Principle
Slide the Teflon on the surface you want to join. In case there is a groove, ensure it fits the groove perfectly.
With the Teflon O-ring between the mating surfaces, you will assemble the two sections. Usually, even when subjected to high compressive force and thermal conditions, the O-ring will expand for better sealing conditions.