Sunday, 01 August, 2021

Nitrile vs Viton Seals and O-Rings


This article will cover the differences between Nitrile vs Viton and how they apply to the various Seals and O-Rings in your motorcycle.

Nitrile vs Viton: About Nitrile Rubber

Nitrile Rubber (commonly referred to as NBR or Buna-N) is what most modern OEM and Aftermarket seals & O-rings on your motorcycle are made of. It has good resistance to chemicals like gasoline, ethanol, and oil. It has an adequate temperature compatibility range, and it is economical to produce.

  • Temperature: Nitrile is effective within a temperature range of -22°F to 212°F.
  • General Suitability: Used for general purpose applications requiring resistance to aliphatic hydrocarbons, petroleum oils, water and hydraulic fluids.
  • Environmental Properties: Nitrile is not resistant to degradation from weather and ozone exposure.

Nitrile vs Viton: About Viton Rubber

Viton Rubber (commonly called fluorocarbon rubber, FKM, or FPM) is a rubber developed by the DuPont company for aerospace applications. It has better temperature & chemical resistance than Nitrile, and unlike nitrile, Viton also resists UV damage and oxidation.

  • Temperature: Viton® seals can withstand temperatures up between -4°F to 413°F.
  • General Suitability: Viton® is best suited for diverse sealing jobs that require high temperature and chemical resistance to fuels, acids, and oils.
  • Environmental Properties: Viton® O-rings and seals have a wide range of chemical resistance (involving mineral acids, fuels, and oils) and this material is also highly resistant to oxidation, UV exposure, fungus, weather, ozone, and mould. This makes Viton® far superior to Nitrile in these regards. They are also designed to resist most oils and lubricants, more importantly petroleum-based lubricants.

What This Means for You

While Nitrile seals have generally “good” resistance to fuel, ethanol, and heat, in our experience it’s not enough for modern fuels and/or modified engines. As the horsepower rises, so too does the heat. As the power level rises, the compression ratio and required octane generally do, too. High heat, especially when combined with ethanol or high octane fuels can lead to premature failure of nitrile seals, hoses, and O-Rings in the fuel system.

The extra heat from a performance engine will also start to degrade the nitrile seals & hoses in other systems, too. (oil sump, transmission, primary, etc.)

As you may have guessed, Viton seals will keep your bike running in top shape and leak free for much longer than their NBR counterparts. The one down side is cost. As usual, better performance isn’t free. Viton Rubber seals and O-rings, in general, are 4-10x more expensive than an equivalent Nitrile Rubber one to produce. However, since we’re talking a production cost of a few cents each, the actual difference in retail price isn’t that much.

One comment on “Nitrile vs Viton Seals and O-Rings

[…] peace of mind? Look into using Viton fuel system components wherever possible. Viton is E85 safe. (Nitrile vs Viton) We’re working on developing Viton Harley CV Carb seals & diaphragms, so keep an eye out […]

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