When choosing a rubber seal for a motorized liquid or gas valve, many people get stuck between Nitrile and Viton rubber. Viton vs Nitrile is a complicated debate, as they both have suitable applications.
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The difference in their chemical makeup influences many aspects of the seal, including density, chemical compatibility, temperature resistance, durability, and pressure ranges.
Choosing the wrong seal for your situation can result in poor performance as well as hazards and emergencies, so you must understand how these synthetic rubbers differ in performance and function.
Consider this your complete guide to Viton vs Nitrile rubber. You can refer to the information in this article when you aren&#;t sure which type of rubber suits your situation.
Viton&#; is a brand name owned by Chemours (spun off from Dupont in ) for the widely used synthetic rubber and Fluorocarbon elastomer (Fkm). It is a popularly used brand, but often used as the generic name for this rubber, like Teflon is to PTFE. It is also sometimes referred to as fluorine rubber or fluoro-rubber.
Fkm/Viton rubber is essential to the sealing industry. It has many impressive characteristics, including temperature resistance and durability. The elastomers are highly fluorinated carbon-based polymers that can resist harsh chemicals and ozone attacks.
Newer products with Viton have improved chemical resistance, so the material is constantly improving. As a result, it&#;s one of the go-to materials for objects subjected to extreme and intense temperature and pressure changes.
Nitrile rubber, or NRB, is a synthetic rubber copolymer of acrylonitrile with butadiene. It&#;s a commonly used elastomer in the seal industry, as it is resistant to many chemicals, including oil and fuel. It is also sometimes called Buna-N, and acrylonitrile butadiene rubber.
It&#;s one of the most resilient materials for seals, making them ideal for long-term uses in harsh conditions. While it can handle changing temperatures, it&#;s ideal for objects that come into contact with dangerous and corrosive solvents and substances.
Since both types of these synthetic rubbers are resistant to drastic temperature changes and harsh chemicals, it may seem like they&#;re interchangeable. But they have a few significant differences worth noting, so you choose the best seal for your project.
Below is a comprehensive comparison of Viton vs NBR seals.
Both Viton and NBR are synthetic rubbers, but they have different compositions. Nitrile rubber uses carbon and hydrogen, creating a butadiene monomer. Viton rubber is carbon, fluorine, and hydrogen, creating a fluorine elastomer.
The fluorine in the Viton is the main difference between the two rubbers and significantly affects durability, flexibility, and other factors. The different materials result in different colors.
Density is one of the differences that result from the various compositions. The fluorine in the Viton rubber makes it stiffer and denser, making it more resilient and less flexible. The density of Nitrile is kg/m3, while Viton rubber has a density of kg/m3.
This pressure range variance is a significant difference. Moreover, it makes the two rubbers behave differently when it comes to flexibility, as Nitrile remains more pliable, while Viton is more likely to stiffen in certain conditions.
As mentioned in the Viton rubber definition, this material is ideal for valves that have to withstand extreme temperatures and unstable environmental conditions. The Viton seal will be the best choice in any scenario where high temperature is the main factor. But if you&#;re dealing with freezing temperatures, the correct choice is more difficult to determine.
Depending on the construction and grade of the seal, a Viton seal can withstand temperatures as low as -20ºC and as high as 210ºC. On the other hand, NRB can withstand temperatures as low as -30ºC and as high as 100ºC.
NRB seals can&#;t compete with Viton seals in situations with high temperatures. But for low temperatures, the Viton can fail in dynamic situations, as the rubber becomes stiff and inflexible. But NRB can stay somewhat flexible in freezing temperatures.
In summary, Viton is the safe choice when you expect drastic temperature changes, especially high ones. But NBR can work better in cold, dynamic situations.
*This article is focused on the differences between NBR and Viton seals, but it should be mentioned that PTFE/Teflon seals are better for high temperature solenoid valves as they have a temperature range of 32°F to 356°F.
While Viton has a relatively consistent pressure range of around 800 PSI, Nitrile rubber comes in different grades, and the pressure range can change dramatically. Depending on the NBR seal you choose, the pressure range can be anywhere between 200 PSI and 3,500 PSI.
The wider pressure range of NBR seals allows the seals to be more flexible but not necessarily more durable.
However, Viton applications typically don&#;t need more than 800 PSI, so the smaller range is often not a reason to opt for the Nitrile. Nevertheless, it&#;s valuable information in case it applies to your situation.
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That being said, when shopping for a solenoid valve, the pressure ranges of a valve body and piping systems won&#;t be able to withstand those higher pressures. The important note between these two seals is that a low pressure solenoid valve with NBR seals will perform better than Viton due to the flexibility of the rubber.
The best reason to choose a quality rubber seal is that your project entails harsh chemicals and dangerous substances that could potentially erode or damage the rubber seal. This consideration is especially applicable to oils.
Nitrile rubber is resistant to petroleum oils, aliphatic hydrocarbon, hydraulic fluids, and water. The last thing you want is a rubber seal slipping off its gasket, compromising the seal and causing issues.
If you use general seals or o-rings, this is likely to happen. But top-quality solenoid valves, whether made with Viton rubber or Nitrile rubber, will be more stable and long-lasting.
Viton can resist harsh chemicals that could affect and damage a Nitrile seal. Viton is resistant to acids, oils, gasses, silicon fluids, aromatic gasses, and halogenated hydrocarbons. For this reason, Nitrile is best for general chemical resistance, while Viton is better for chemical processing appliances, such as automotive purposes.
If you&#;d like to see a more comprehensive list of chemicals or to find a specific chemical&#;s compatibility, try looking up Viton and NBR in our free compatibility chart for chemicals.
The difference in durability when discussing Viton vs Nitrile is complicated. They are both highly durable in different ways.
Generally, people consider Viton the more durable option for seals that may face exposure to weather, UV, ozone, or other harsh environmental elements. Viton is less likely to disintegrate from wear and tear thanks to its stiff structure and dense composition.
However, Nitrile is impressively durable as well. NBR seals are tear-resistant, so they can stretch and flex without ripping! The elasticity of the Nitrile rubber allows it to put up with more dynamic situations, while Viton is more rigid. As a result, Viton is more likely to snap and become useless if forced into a stretch or bend. A torn seal can also result in an emergency.
Viton vs Nitrile in the durability category could be considered a tie, but it depends on the application and external elements.
In summary, NBR seals are more durable in dynamic situations where flexibility is important, and Viton seals are more resistant to external elements and harsh conditions.
Hopefully, this article has helped you better understand Viton vs Nitrile. While some consider Viton the superior rubber, it truly depends on the situation and factors involved.
Nitrile rubber is the ideal material in several scenarios, especially when the seal has to be dynamic and move with the gasket. But when it comes to overall toughness, Viton can&#;t be beaten. So ensure you consider all the crucial factors discussed above before making your decision.
Choosing the wrong rubber seal can result in disaster, so use this article to help you make an informed decision and avoid problems. It&#;s also important to always use quality solenoid valves with the best rubber seals. Don&#;t risk anything by using standard o-rings or seals made of low-quality rubber.
NBR is an acronym for nitrile butadiene rubber but goes by many other names, such as nitrile or buna. NBR is a synthetic rubber compound made from acrylonitrile and butadiene. Buna is renowned for its natural resistance to oils, fuels, water and many other chemicals.
You may use NBR for most hydraulic applications, especially those within the typical operating parameters of a basic hydraulic system. Anti-wear mineral oil, water-glycol and high water-based fluids are suitable for combining with NBR seals.
NBR is stable over a wide thermal range of &#;40° to 226°F (&#;40° to 108°C), which is well within the usable range of any hydraulic system. Furthermore, Buna is reliable even in the outer reaches of the above temperature range and even in the presence of contamination and chemicals.
Buna is a great all-around performer in the fluid power world but doesn&#;t operate well in the extreme ends of the performance spectrum. If your machine operates in ambient conditions colder than &#;40°F (&#;40°C) and hotter than 226°F (108°C), you may want to select a different polymer.
Moreover, some fluids are not compatible with NBR, such as polyol esters. Also, some chemical environments are not suitable, such as those with ammonia vapor that may contaminate the oil.
Although Buna is stable down to &#;40°F (&#;40°), it doesn&#;t mean it&#;s suitable to operate when ambient cold is that extreme. The seals will shrink and reduce their ability to seal, especially under pressure. Realistically, consider the lower range of NBR seals in hydraulics to be &#;20°F (&#;29°C).
That being said, some manufacturers offer specialty compounds rated for as low as &#;65°F (&#;54°C), such as military-grade NBR. If you have a low-temperature application, reach out to your preferred seal supplier.
Buna works great to seal both piston and rod seals in a cylinder. However, they have their limitations. An NBR piston t-seal offers very low leakage even at high pressure. However, the NBR compound counts upon an interference fit between the piston and barrel, and that fitment results in high friction. Expect not much more than a few feet/second maximum velocity for a buna piston seal.
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