05 Mar Comparing O-Ring Materials: Buna-N vs Viton™ vs. EPDM
Seals fail for various reasons, but often the wrong O-ring material is the culprit. The material an O-ring gasket is made of influences how well it resists heat, chemicals, weather, and everyday wear.
At I.B. Moore Manufacturing, our experts know that seals aren’t one-size-fits-all. Buna-N rubber, Viton™ material, and EPDM are among our most-used materials, and we choose them carefully to prevent costly failures before they occur.
Let’s see how these three materials stack up against each other.
Buna-N Rubber Makes Sense for Everyday Use
Buna-N rubber, also called nitrile rubber or NBR, is the most common O-ring material on the market. It works well with petroleum-based oils, fuels, and hydraulic fluids, which cover a wide range of everyday mechanical and industrial applications. It also withstands temperatures from -40°F to 250°F (-40°C to 121°C), so it handles most standard operating conditions without issue.
Another reason Buna-N rubber is so popular is its price. Since it’s widely produced and easily manufactured, it costs less than most specialty materials and is a practical starting point for many applications.
That said, it does have limits. Buna-N rubber does not hold up to sunlight, ozone, or certain chemicals, like ketones. It’s not a good fit for outdoor equipment or environments with UV exposure. Buna-N rubber is a solid, affordable choice for any indoor application involving oil or fuel.
Viton™ Material Resists High Heat and Chemicals
This is a step up in performance, with a correspondingly higher price. Made by Chemours (originally by DuPont), Viton™ is a fluoroelastomer (synthetic rubber) designed to resist heat and chemicals that quickly break down other O-ring materials. It performs reliably from -15°F to 400°F (-26°C to 205°C), and is well-suited for fuel systems, aerospace components, and chemical processing equipment.
EPDM O-Rings for Water and Outdoor Conditions
EPDM, short for ethylene propylene diene monomer, is the go-to material when water, steam, or outdoor exposure is involved. It stands up to ozone, UV rays, and poor weather conditions far better than Buna-N rubber or Viton™ material, so it’s a reliable choice for plumbing systems, HVAC equipment, and outdoor applications. EPDM handles a temperature range of -65°F to 300°F (-54°C to 149°C).
But while EPDM isn’t afraid of water, steam, alcohols, and similar fluids, it degrades quickly when exposed to petroleum-based oils or fuels. Using EPDM in a fuel system would cause it to fail quickly, as the two are incompatible. Its real strength lies in wet environments and outdoor settings where weather resistance matters most.
How the Three Materials Compare
In the Buna-N vs. Viton™ comparison, the main question is how demanding the environment is. Viton™ material is worth the added cost for applications with aggressive chemicals, high heat, or fuels containing aromatic compounds; Buna-N rubber would degrade too quickly in those same conditions.
As for EPDM vs. Viton™, these two materials serve opposite purposes. Viton™ excels with oils and fuels, while we recommend EPDM for water and outdoor exposure. The choice between them is clear once you know what the seal will face.
The Buna-N vs. EPDM comparison is all about the fluids used in the application. Buna-N rubber handles
petroleum-based oils and fuels but degrades when exposed to water; it breaks down under sunlight and ozone. EPDM is the opposite: It thrives in wet outdoor environments but fails when it comes into contact with petroleum-based fluids. There’s minimal overlap between the two.
Choosing Between Buna-N vs. Viton™ vs. EPDM
The simplest way to compare these three materials is to look at what they’re up against. Buna-N rubber handles oil and fuel well and costs the least, making it a smart starting point for many indoor applications. Viton™ material is the better option when the heat gets intense or chemicals get aggressive. EPDM is the right choice for water, steam, and outdoor conditions because no other commonly used gasket material withstands weathering as well.
The biggest mistake people make is choosing based on price alone without checking whether the material is compatible with the fluids or environment involved. A seal that fails in two months costs far more than the right one installed once. Most manufacturers publish compatibility guides, and a quick check before buying can prevent a lot of trouble.
When It Comes to Custom Sealing Solutions, No Company Compares to I.B. Moore Manufacturing
Our team works with Buna-N rubber, Viton™, EPDM, and a range of other materials to match the right seal to specific applications. Whether the concern is heat, chemical exposure, or outdoor weathering, we’ll point you in the right direction. Our team looks forward to discussing your sealing needs and helping you with your next project. Contact our Lexington, KY, team for nationwide service.