Selecting the ideal material for seals and gaskets is a critical engineering decision. While both EPDM (Ethylene Propylene Diene Monomer) and Silicone are industry staples for molded and extruded applications, their chemical compositions lead to distinct performance advantages.
Understanding these nuances—especially regarding fire safety and specialized industry requirements—is key to ensuring long-term part integrity.
Material Comparison: At a Glance
Feature | EPDM | Silicone |
Temperature Range | -50°C to +150°C | -60°C to +230°C+ |
UV & Ozone Resistance | Excellent | Excellent |
Chemical Resistance | High (Acids/Alkalis) | Moderate |
Tensile Strength | High | Low to Moderate |
Abrasion Resistance | Good | Poor |
Cost | Generally Lower | Generally Higher |
EPDM: The Rugged, Cost-Effective Workhorse
EPDM is favoured for its exceptional durability in outdoor environments. Its molecular structure allows it to withstand weathering, water, and aging without significant degradation.
- Best For: HVAC systems, automotive weatherstripping, and roofing membranes.
- Key Advantage: It is highly resistant to alkalis and acids, making it a go-to for chemical processing environments where harsh fluids are present.
- Limitation: Like silicone, it is not recommended for environments involving constant exposure to oil or gasoline.
Silicone: The High-Heat Specialist
Silicone excels where temperature extremes and electrical insulation are the primary concerns. It maintains its physical properties across a massive thermal window.
- Best For: Medical devices, food processing, and high-heat industrial seals.
- Key Advantage: It possesses an excellent compression set, meaning it returns to its original shape even after prolonged pressure under heat.
- Limitation: It is relatively “soft.” It should be avoided in applications requiring high tensile strength or resistance to abrasion, tearing, and cut growth.
The Fire Rating Factor: Safety First
When it comes to fire safety, the choice often shifts toward specialized compounds.
- Silicone: Naturally possesses better flame resistance and produces low smoke toxicity. It can be formulated to meet stringent UL 723 ,ASTM E84 Class A , UL 94 V-0 flame ratings.
- EPDM: While standard EPDM is flammable, it can be engineered with specific flame-retardant additives to meet safety standards, though this can sometimes impact other physical properties.
Niche Applications & Industry Excellence
- Defense
In military applications, materials must survive “worst-case” scenarios. Silicone is often utilized for its electromagnetic interference (EMI) shielding capabilities and stability in extreme climates. EPDM is used for ruggedized external seals on ground vehicles due to its abrasion resistance.
- Marine
The marine environment is a relentless assault of salt water and UV radiation. Both materials offer the ozone resistance needed to prevent “dry rot,” but EPDM is frequently chosen for hatch seals and portlight gaskets because it stands up better to the mechanical wear of opening and closing.
- Oil and Gas
While neither material is suited for direct contact with hydrocarbons (oil/gasoline), they serve vital peripheral roles.
- Silicone is used in high-heat electronics and sensors within refineries.
- EPDM is used for water-handling systems and secondary containment seals where acid/alkali resistance is paramount.
Making the Final Decision
To determine if EPDM or Silicone is right for your project, you must weigh the end-use function against physical, mechanical, and chemical resistance requirements.
At Berzelius , our engineers specialize in navigating these material complexities. We work directly with your team to review application data and ensure the elastomer you choose isn’t just “good enough,” but optimized for the life of your product.
FAQ
EPDM offers excellent weather and chemical resistance, while silicone provides superior high-temperature performance and flexibility.
Silicone is better for high temperatures, handling up to +230°C or more, while EPDM typically withstands up to +150°C.
Yes, EPDM generally has higher tensile strength and better abrasion resistance, making it more durable in mechanical applications.