NBR vs FKM vs EPDM vs Silicone: Complete Rubber Comparison Guide 2026

Four compounds — NBR, FKM/Viton, EPDM, and Silicone — account for roughly 80% of industrial sealing specifications. Choosing among them directly determines seal life, leak rate, and maintenance cost. This guide compares these four elastomers across temperature, chemical resistance, mechanical properties, and cost, so you can match the compound to the duty instead of guessing.

Key Takeaways (TL;DR)

• NBR — lowest cost; best for oil and grease up to 120°C; fails in weather, ozone, and steam.
• FKM / Viton — best fuel and chemical resistance to 205°C; highest unit cost; avoid standard grades in steam (use steam-resistant FKM).
• EPDM — best weather, ozone, and hot-water/steam resistance to 150°C; incompatible with petroleum oil (swells rapidly).
• Silicone — widest temperature range (−60 to 230°C) and the only one with broad food/medical grades; weak in oil and abrasion.
• Rule of thumb: start with NBR, and step up only when temperature, fluid exposure, or compliance (FDA/ISO) forces it.

Quick Comparison Table

Detailed Analysis by Application

Automotive Sealing

Best: FKM or NBR. FKM (continuous service to 205°C, excellent resistance to gasoline, diesel, and synthetic lubricants) is the standard for fuel-system seals, turbocharger hoses, and crankcase gaskets. NBR (rated to 120°C) is the cost-effective choice for engine-oil and transmission seals where peak temperature stays below ~120°C. Above 150°C in a fuel environment, NBR hardens and cracks within months, so FKM is the engineering-correct upgrade.

Outdoor & Weather Exposure

Best: EPDM. With near-total ozone and UV immunity and service to 150°C in hot water and steam, EPDM is the default for roofing membranes, window and door seals, and agricultural equipment. Its one hard limit is petroleum oil: immersed NBR/EPDM parts swell 100%–300% and lose seal force within days, so never use EPDM where it contacts fuel or mineral oil.

Food & Medical

Best: Silicone (FDA / LFGB). Silicone is the only material here with broad food- and medical-grade availability and a −60 to 230°C range, making it suitable for baking seals, dairy and beverage lines, and implanted or surgical devices (with ISO 10993 / USP Class VI grades). Its weakness is mechanical: low tear strength and poor oil resistance mean it should not carry load or sit in lubricated assemblies.

Real-World Example

A hydraulic power unit in a steel mill originally ran NBR rod seals in a mineral-oil circuit that stabilized near 110°C. The seals hardened and cracked after roughly six months, causing planned downtime every two shutdowns. Re-specifying the same geometry to FKM — rated for continuous −26 to +205°C service — extended the replacement interval to three years or more, about a 6× life improvement. The higher per-part cost was recovered several times over through avoided unplanned downtime, illustrating the core rule: pay for the material the temperature and fluid actually demand.

Common Mistakes to Avoid

• Using EPDM in petroleum oil → rapid swelling and failure
• Using silicone in oil → swells and loses mechanical strength
• Using NBR above 120°C → thermal degradation, hardening, cracking
• Using standard FKM for steam → short service life; specify special steam-resistant grades

Cost Optimization Strategy

For cost-sensitive applications that don’t need premium performance, use the hierarchy: NBR → EPDM → Silicone → FKM. NBR is typically the lowest-cost option, while FKM often runs 3–5× the per-part cost of NBR. Only upgrade to a more expensive material when the application’s specific requirements demand it. In practice this means defaulting to NBR for general oil sealing, EPDM for weather and water, Silicone for extreme temperature or food/medical contact, and reserving FKM for heat, fuel, and aggressive chemicals.

Standards & Further Reading

Material specifications referenced above follow widely used industry standards: ASTM D2000 for rubber classification by properties, ISO 1629:2013 for rubber and latices nomenclature, and the material overviews at Fluorocarbon rubber (FKM), Nitrile rubber (NBR), EPDM, and Silicone rubber.

Bottom Line

There is no single “best” rubber — only the right rubber for the duty. Match the compound to the three constraints that actually kill seals: the temperature ceiling, the fluid or chemical it contacts, and any compliance requirement (FDA, ISO 10993, 3A). When in doubt, NBR is the cost-effective default; step up to FKM for heat and fuel, EPDM for weather and water, and Silicone for extreme temperature or food/medical contact.

Learn more about our FKM rubber products.

Learn more about our silicone molded parts.

Explore our Custom Rubber Parts for materials, specifications, and custom manufacturing options.