How to Choose the Right O-Ring Material (NBR, FKM, Silicone & EPDM Explained)
Share
Not all O-rings are created equal.
Each material has its own strengths — from heat and chemical resistance to flexibility and cost — and choosing the right one can make the difference between a perfect seal and a premature failure.
Here’s a quick guide to the most common O-ring materials and where each works best.
NBR (Nitrile) O-Rings
Best for: Oils, fuels, air, water, general purpose use
Temperature range: -30 °C to +100 °C (up to 120 °C for short periods)
NBR, or nitrile rubber, is the most widely used O-ring material. It’s tough, reliable, and ideal for everyday sealing jobs — especially where oil, fuel, or hydraulic fluids are involved.
Because of its balance of performance and price, it’s the go-to choice for automotive, hydraulic, and pneumatic systems.
Shop NBR O-Rings → Nitrile (NBR) O-Rings – Fuel, Oil & Hydraulic Seals | SealWithSelo – Seal with Selo
FKM (Viton®) O-Rings
Best for: High temperature, chemicals, fuels, oils
Temperature range: -20 °C to +200 °C
FKM, commonly known by the brand name Viton®, steps up where nitrile leaves off. It’s excellent for sealing in harsh environments — handling high temperatures, aggressive fuels, and a wide range of chemicals.
If you’re working with engines, turbo systems, or industrial equipment exposed to heat and solvents, FKM is the smarter choice.
Shop FKM O-Rings → Buy FKM Rubber O-Rings | Viton® FKM O-Ring Seals – SELO – Seal with Selo
Silicone O-Rings
Best for: Heat, flexibility, and clean sealing applications
Temperature range: -50 °C to +200 °C
Silicone offers outstanding flexibility and temperature stability. It stays soft even in extreme cold, which makes it ideal for static sealing and for equipment that needs clean, non-reactive materials — like beverage systems, medical devices, and electronics.
However, silicone isn’t suited to fuel or oil exposure, so it’s better for air, water, or food-related use.
Shop Silicone O-Rings → Red Silicone O-Rings – High Temp & Hygienic Seals | SealWithSelo – Seal with Selo
EPDM O-Rings (Coming Soon to Selo)
Best for: Water, steam, and brake fluid applications
Temperature range: -40 °C to +150 °C
EPDM performs where most other rubbers can’t. It’s resistant to water, steam, and glycol-based brake fluids, making it popular for plumbing, braking systems, and outdoor sealing applications.
Just remember: EPDM and oil don’t mix — avoid using it with petroleum-based fluids.
Shop EPDM O-Rings → EPDM O-Rings – Water, Steam & Brake Fluid Seals | SealWithSelo – Seal with Selo
Quick Comparison Table
| Material | Common Uses | Temperature Range | Key Strength | Not Suitable For |
|---|---|---|---|---|
| NBR (Nitrile) | Oil, fuel, air | -30 °C → +100 °C | Cost-effective, tough | Ozone, sunlight |
| FKM (Viton®) | High heat, fuel, chemicals | -20 °C → +200 °C | Chemical + heat resistance | Low temperatures |
| Silicone | Heat, clean sealing, air | -50 °C → +200 °C | Flexibility, non-reactive | Fuels, oils |
| EPDM | Water, steam, brake fluid | -40 °C → +150 °C | Weather + water resistance | Oils, hydrocarbons |
Choosing the Right Material
If you’re sealing oil, fuel, or hydraulics, go for NBR or FKM.
For heat and chemical exposure, choose FKM.
If you need flexibility and clean sealing, Silicone is ideal.
For water and steam systems, EPDM is the right match.
Still unsure? Get in touch — we’ll help identify the best option for your application.