When it comes to choosing the right rubber material for seals, gaskets, or hoses, two names often come up: Viton® (FKM) and EPDM. While they may look similar on the surface, their performance characteristics differ significantly depending on temperature, chemicals, environment, and cost.
This guide will walk you through their differences, advantages, and ideal use cases—so you can make informed decisions for your next project.
Part 1: Material Overview
What is EPDM?
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber widely used for outdoor and water-based applications. It offers excellent resistance to:
Steam and hot water
UV rays and ozone
Weathering and oxidation
Certain polar fluids (e.g., ketones, alcohols, brake fluid)
It is flexible at low temperatures and highly durable in outdoor conditions.
What is Viton?
Viton®, a brand of FKM (fluoroelastomer) developed by DuPont, is designed for high-performance sealing in extreme environments. It’s best known for:
Exceptional heat and chemical resistance
Compatibility with fuels, oils, acids, and solvents
Long service life under pressure or high temperature
Low permeability and excellent compression set
Part 2: Temperature Resistance
| Property | EPDM | Viton® (FKM) |
|---|---|---|
| Operating Range | –45 °C to +145 °C (–49 °F to 293 °F) | –20 °C to +210 °C (–4 °F to 410 °F) |
| Peak Performance | Excellent cold flexibility | Superior heat resistance |
Verdict: EPDM works better in extremely cold environments; Viton is more stable at high temperatures.
Part 3: Chemical Compatibility
| Property | EPDM | Viton® (FKM) |
|---|---|---|
| UV/Ozone Resistance | ✅ Excellent | ✅ Very Good |
| Abrasion Resistance | ⚠️ Moderate | ✅ High |
| Compression Set | ✅ Good | ✅ Excellent |
| Flexibility | ✅ Excellent at low temp | ⚠️ Less flexible in cold |
| Aging & Weatherability | ✅ Superior | ✅ Good |
Verdict: Choose EPDM for water, steam, and glycol-based fluids. Choose Viton when fuel, oil, or harsh solvents are involved.
Part 4: Environmental and Mechanical Properties
| Property | EPDM | Viton® (FKM) |
|---|---|---|
| UV/Ozone Resistance | ✅ Excellent | ✅ Very Good |
| Abrasion Resistance | ⚠️ Moderate | ✅ High |
| Compression Set | ✅ Good | ✅ Excellent |
| Flexibility | ✅ Excellent at low temp | ⚠️ Less flexible in cold |
| Aging & Weatherability | ✅ Superior | ✅ Good |
EPDM is ideal for outdoor or rooftop exposure, while Viton performs better in tight tolerance or high-pressure sealing where compression resistance is critical.
Part 5: Cost and Availability
EPDM is inexpensive, widely available, and easy to mold—ideal for high-volume, cost-sensitive projects.
Viton® is premium-priced (up to 8× the cost of EPDM) and used when durability under extreme chemical or thermal conditions is essential.
Part 6: Application Examples
| Application | Recommended Material |
|---|---|
| Steam valves and hot water lines | EPDM |
| Automotive fuel systems | Viton |
| Window seals, roofing membranes | EPDM |
| Chemical reactors and tanks | Viton |
| Brake fluid lines (non-oil based) | EPDM |
| Petrochemical sealing | Viton |
Part 7: FAQ
Q1: Can I use EPDM for oil-based fluids?
No. EPDM is not compatible with most oils and fuels. It will swell or degrade over time.
Q2: Is Viton safe for outdoor UV exposure?
Yes, though EPDM performs better in constant UV or ozone environments.
Q3: Which one is better overall?
It depends entirely on your operating environment. EPDM wins in water, steam, and outdoor conditions. Viton excels in fuel, solvent, and high-heat systems.
Conclusion: Which One Should You Choose?
| Scenario | Best Choice |
|---|---|
| Low-temperature flexibility | EPDM |
| High-temperature durability | Viton |
| Fuel and oil resistance | Viton |
| Outdoor weather exposure | EPDM |
| Cost-sensitive sealing applications | EPDM |
| Harsh chemical resistance needed | Viton |
Use EPDM if your application involves water, steam, or weather. Use Viton when oil, fuel, or aggressive chemicals are present—and when long-term sealing under heat and pressure is critical.
