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AN O-Rings

Our o-rings are available in Black Buna-N 70D or Black Chemours Viton 75D material. Sizes available are -6AN, -8AN, -10AN, -12AN, -16AN and -20AN

Buna-N (Nitrile) is an affordable, general-purpose synthetic rubber ideal for coolants, petroleum oils and hydraulic fluids at moderate temperatures. Viton (FKM/fluoroelastomer) is a high-performance material providing elite resistance to extreme heat, harsh chemicals, and outdoor weathering.

Temperature Ranges
  • Buna-N: Handles -40°F to 250°F (-40°C to 121°C); performs better in colder environments.
  • Viton: Handles -15°F to 400°F (-26°C to 204°C) continuously, with short spikes up to 600°F (315°C)
Chemical and Environmental Resistance
  • Buna-N: Resists standard oils, fuels, and water well, but degrades quickly when exposed to ozone, sunlight, UV rays, and strong acids.
  • Viton: Resists aggressive acids, concentrated chemicals, solvents, ozone, and UV light, but can fail when exposed to ketones, hot water/steam, or specific aviation fluids.

Buna-N is generally better for pure ethanol, while Viton handles blended fuels well but swells severely in pure methanol.

Why Viton Wins with Race Fuel
  • Aromatic Hydrocarbons: High-octane race fuels achieve their knock resistance using dense concentrations of highly aromatic hydrocarbons (such as toluene and xylene). Standard Buna-N suffers massive volume swell and structural softening when exposed to these aromatics. Viton resists aromatic hydrocarbons almost perfectly, maintaining its shape and sealing force.
  • Tetraethyl Lead (TEL): The lead additive itself does not chemically attack either elastomer, but leaded fuels are inherently strictly petroleum-based (no ethanol). While Buna-N can handle standard low-lead aviation fuel (like Avgas 100LL) under moderate conditions, highly concentrated racing formulations will degrade it.
  • Thermal Endurance: High-octane racing environments inherently generate extreme engine bay and fuel system temperatures. Viton handles these thermal spikes safely up to 400°F (204°C), whereas Buna-N will prematurely harden and crack when pushed past 250°F (121°C)
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