When we compare the two, Viton is more temperature resistant but lacks the chemical resistance of Teflon (PTFE). On the other hand, Teflon is better in terms of non-adhesive properties but is less thermal resistant. In addition, Viton has better sealing capability than Teflon due to the rigidity of the plastic on Teflon.
There are several other differences between Viton & Teflon (PTFE) O-rings. We have discussed the characteristics of both Viton & Teflon (PTFE) O-rings in this article. After exploring these options, you’ll be empowered to make a confident choice between the two.
What are O-rings?
O-rings are round. These are mechanical seals available on the market to help seal different passages. These rings help protect from leakage. You might have seen it numerous times in daily life but might have been unable to identify it.
O-rings are made of different materials and come in different sizes. Some of the properties of these rings are similar, while some differ from one another. O-rings are usually temperature, chemical, and electricity-resistant. The caliber of its excellent resistance depends on the material used for O-ring manufacture and silicone O-rings.
Here we have compared two of the most widely available O-ring materials, Viton and Teflon (PTFE). Knowing the differences and their properties will help you make an informed decision.
Characteristics of Viton O-rings
Viton O-rings are made up of synthetic rubber and fluoropolymer elastomer. Due to their durability, Viton O-rings are the top choice of many people worldwide. These O-rings can easily survive challenging conditions. Due to its numerous features, it is widely used as a sealing material for moving objects.
Different grades of Viton O-rings are available in the market depending upon the type of their usage. Viton has good mechanical properties and is known for its durability, flexibility, and resistance to tearing. Due to its brilliant composition, it is used in many applications. Using these rings as seals reduces maintenance, as there is minor wear and tear due to their durability.
Viton O-rings are more expensive than other nitrile o rings. Using Viton seals will generally result in less downtime for the appliances than other materials. Viton O-rings are resistant to fuels, oils, and many other chemicals.
The Viton seals exert less pressure on the stem itself as compared to its Teflon counterpart while still providing a good seal. Both of these require the top of the guide to be machined so that the seal is secured to the guide and doesn’t move up and down with the valve stem. This is the “positive” sealing nature of this particular type of seal. With the Viton seal exerting less pressure on the stem, then the tendency for the seal to come loose from the guide and act like an umbrella seal is also much less than the Teflon style.
These rings are available in several different grades depending upon the nature of use. Viton A grade is the most widely used as its fluorine content is 66%. Some other commonly used qualities include grades B and F. Many other grades are available on the market. You can choose the one that best fits your needs by discussing it with a Viton O-rings professional.
Some of the characteristics of Viton O-rings are mentioned below. Let’s discover together!
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Chemical Resistance
Viton O-rings have high chemical resistance. It is compatible and works with so many chemicals that it is easier to list down those it is not compatible with. Petrochemicals, biodiesel, oils, oxygen-plasma, high-vacuum, and silicon greases and oils are just a few chemicals it is resistant to. Due to its vast resistant nature, it is widely used and one of the most versatile O-rings.
Viton O-rings are not compatible with ketones. It crudes with some of the chemicals, so it is best that you check beforehand to save yourself and others from any mishap. It can also sustain harsh weather conditions, mold, ozone, and fungus. These resistance properties make it easier to keep them maintained.
Temperature Range
Viton offers a greater temperature resistance but falls short of Teflon’s (PTFE) chemical resistance. As mentioned earlier, there are different grades of Viton O-rings. The Viton O-ring temperature limit range that all the stages of Viton O-rings can survive is from -26°C to +205°/230°C Celsius. Whereas in Fahrenheit, the content is from -15°F to +400°/440°F. It can work in high-temperature conditions reasonably quickly. Moreover, unlike extremely high-temperature resistance, they are not flexible enough to sustain low temperatures.
Hence, Viton O-rings are durable and compatible with high-temperature applications and should be avoided in the lower temperature range. If the content of temperature increases from the upper limit, the ring starts to melt. Whereas, if used in low-temperature performance, the O-rings do not function properly and become inflexible and stiff.
Size of Viton O-rings
Viton O-rings come in various sizes. The three points to measure O-rings from are inner diameter (ID), outer diameter (OD), and cross-section (CS). Each ring has a different ID, OD, and CS. Knowing where to use the O-ring beforehand helps you better understand which size to choose.
Limitations of Viton O-rings
Viton seals are not compatible with certain chemicals. Moreover, unlike extremely high-temperature resistance, they are not flexible enough to sustain low temperatures. The substances that Viton seals are not compatible with are:
- Ketones
- Skydrol fluids
- Amines
- low gas permeability
- Hot chlorinated hydrocarbons and mineral acids
- Nitro hydrocarbons
Applications of Viton O-rings
It is easily used for applications that require a low compression set and extremely high temperatures. It is compatible with aircraft, mechanical devices, automobiles, fuel-transporting cars, different values, pumps, and the chemical industry. It is also used in industries where petroleum is refined.
Because they can sustain high temperatures, Viton O-rings are also used in explosive environments.
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Characteristics of Teflon (PTFE)
Teflon (PTFE) O-rings are made up of Polytetrafluoroethylene material. PTFE is white and is a famous and widely used material for O-rings. In some scenarios, Teflon (PTFE) O-rings are preferred over regular elastic O-rings.
Teflon seals have several advantages as compared to elastomers. Corrosion resistance, electrical properties, a more comprehensive range of temperatures, heat resistance, oil resistance, and longer shelf life are some advantages.
These rings have low friction, work well in low and medium-pressure applications, and are soft and elastic. Due to low friction, they are ideal for many appliances. Moreover, it does not change its size when moisture is absorbed.
Apart from all these features, PTFE O-rings have certain drawbacks too. Characteristics of this ring material are discussed below for you to understand them.
Chemical Resistance
Teflon (PTFE) O-rings are one of the most corrosion-resistant materials on the market. PTFE seal’s resistance makes it easier for the rings to last longer and sustains their chemical compatibility. It is compatible to be used with almost all the chemicals that are used in industrial applications. Where all rubber compounds fail, you can utilize PTFE material efficiently. It is compatible with different materials, including oils, acids, bases, and other chemicals.
Furthermore, Teflon (PTFE) O-rings are more resistant and durable, which results in longer shelf life. In the long run, most of the O-rings wear and tear up. Teflon seals’s resistance makes it easier for the rings to last longer and sustains their chemical compatibility. It also provides abrasion resistance.
Temperature Range
Teflon (PTFE) O-rings have high resistance to high and low temperatures. In high temperatures, where all other materials fail, Teflon seals work the best. Higher temperatures can result in rubber O-rings melting or losing their resistance, while in lower temperature ranges, rubber O-rings become hard and lose their elasticity.
Teflon (PTFE) O-rings work best in these scenarios because of the polytetrafluoroethylene material. Due to its actual temperature range, you can use it in extreme temperatures. Teflon (PTFE) O-rings are used in combustion processes and appliances and processes in colder environments. Several gasket manufacturers now offer a material made of PTFE and fine stainless steel particles. The gasket is inflexible, but has the same temperature resistance as PTFE and resists cold flow.
The temperature range for Teflon seal material in Celsius is from -200°C to 250°C. Whereas in Fahrenheit, the temperature range is from -328°F to 482°F.
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Size of Teflon (PTFE) O-ring
Like Viton O-rings, Teflon (PTFE) O-rings are also of various sizes. By measuring the inner diameter (ID), outer diameter (OD), and cross-section (CS) of an O-ring, you can get to know the size of that ring. Custom O-rings can also be made per your measurements and specifications if all available sizes are unsuitable for your application.
Limitations of Teflon (PTFE) O-ring
With all the advantages of Teflon (PTFE) O-rings, there are several limitations too. Teflon seals are complex as compared to nitrile O-rings. Moreover, the leakage rate is also higher in these. Teflon seals require special finishing after installation to control and lower the leakage rate. These seals cannot be installed multiple times or reused. It becomes dispensable after a single use, unlike rubber seals. Also, Teflon is slightly less thermally resistant but offers much more in the way of non-adhesive properties.
PTFE material is also a premium product. Again, if your application involves anything less than the most extreme temperatures, pressures, and aggressive chemicals, then a cheaper alternative might be preferable.
Due to all these factors, PTFE is only preferred in the extreme temperature range and when higher chemical resistance is required. Otherwise, most of the time, rubber compound O-rings are preferred over Teflon seals.
Applications of Teflon (PTFE) O-ring
Teflon (PTFE) O-rings are used in several different industries, including but not limited to the food and beverage industry, mechanical engineering, automotive, electronics & semiconductors, aerospace, and oil & gas.
Furthermore, PTFE seals are used in several pumps, transmissions, gearboxes, and rotary or screw-type air compressors. Due to its higher friction, temperature, and chemical resistance, you can easily use it in harsh environments where there is more likely a chance of wear and tear.
These rings are also water resistant and do not lose their durability quickly. Due to their extended shelf life, appliances can run longer without getting serviced or changing their rings. This does not affect their flexibility or durability at all. Thanks to all the qualities of O-rings, it is the top choice where there is a chance that all rubber compounds will fail.
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Conclusion
When selecting between Viton and PTFE for industrial applications, it often depends on the specific requirements of the application and the conditions the materials will be subjected to. It is essential to know the environment where the O-rings will be used.
Understanding the environment and circumstances where the O-ring will be used will help you decide which O-ring material will be the best choice. What works best in one circumstance might not work in the other. Hence, it is best to know about the Encapsulated O-rings and the usage conditions.
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