O-Rings by Material
NBR is the correct default material for 90% of petroleum-oil sealing applications, but selecting the wrong elastomer causes rapid failure regardless of size or groove design. This overview covers the core elastomer families for o rings—NBR, FKM, EPDM, VMQ, PTFE, FFKM, PU, CR and AFLAS—plus rubber o rings, metal o rings, specialty sealing options and o ring kit formats for industrial, automotive, food, and chemical service. Temperature ranges, chemical compatibility, and cost indices are provided for each material. For detailed design guidance, visit our [O-Ring Engineering Hub](/engineering/) and [Seal Selection by Function](/guides/seal-selection-by-function/) pages.
Nitrile (Acrylonitrile Butadiene)
Temperature: -40C to +120C
- Best for: Petroleum oils, hydraulic fluids, fuels
- Avoid: Ozone, ketones, chlorinated solvents
Hydrogenated Nitrile (HNBR)
Temperature: -40C to +150C
- Best for: Sour gas, automotive, high-pressure hydraulics
- Avoid: Polar solvents, steam, aromatic hydrocarbons
Fluorocarbon (Viton)
Temperature: -20C to +200C
- Best for: High temperature, chemicals, aggressive fuels
- Avoid: Ketones, steam, hot concentrated alkalis
Ethylene Propylene Diene Monomer
Temperature: -50C to +150C
- Best for: Water, steam, HVAC, outdoor/UV exposure
- Avoid: Petroleum oils, fuels, mineral hydraulic fluids
Silicone (Vinyl Methyl Silicone)
Temperature: -60C to +230C
- Best for: Food/pharma, extreme temperatures, static seals
- Avoid: Dynamic sealing, petroleum oils, high pressure
Polytetrafluoroethylene
Temperature: -200C to +260C
- Best for: Universal chemical resistance, static seals
- Avoid: Dynamic sealing, applications needing elasticity
Perfluoroelastomer (Kalrez)
Temperature: -15C to +325C
- Best for: Extreme chemicals, high temp, semiconductor
- Avoid: Molten alkali metals, very high cost apps
Polyurethane (AU / EU)
Temperature: -35C to +80C
- Best for: High-pressure hydraulics, pneumatics, dynamic seals
- Avoid: Hot water, steam, glycol, polar solvents
Chloroprene Rubber (Neoprene)
Temperature: -40C to +120C
- Best for: Refrigerants, marine, outdoor/HVAC
- Avoid: Aromatic fuels, ketones, strong oxidizers
Tetrafluoroethylene Propylene (FEPM)
Temperature: -5C to +230C
- Best for: Steam, sour gas, caustic chemicals, amines
- Avoid: Aromatic hydrocarbons, ketones, chlorinated solvents
FEP / PFA Encapsulated Silicone / FKM
Temperature: -60C to +260C
- Best for: Universal chemical resistance, food/pharma
- Avoid: Molten alkali metals, abrasive slurries
Toroidal Rubber O-Rings (NBR, EPDM, Silicone, FKM)
Temperature: -60C to +200C
- Best for: Hydraulic, fuel, water and static groove sealing
- Avoid: Applications needing a flat flange gasket
Stainless Steel & Inconel Metal O-Rings / C-Rings
Temperature: -270C to +800C
- Best for: Extreme temperature, vacuum, high pressure, cryogenic
- Avoid: General-purpose elastomer applications
Custom Flat Gaskets (EPDM, NBR, Silicone, FKM, PTFE)
Temperature: -200C to +260C
- Best for: Flanges, manways, enclosures, custom flat seals
- Avoid: Dynamic motion, ultra-high pressure without backup
O-Ring Kits & Assortments
Temperature: -60C to +325C
- Best for: Maintenance, MRO, field service, prototyping
- Avoid: Single-material critical seals (buy specific)
Spring Energized PTFE Seals
Temperature: -253C to +300C
- Best for: Aggressive chemicals, vacuum, cryogenic and low-friction dynamic sealing
- Avoid: Low-cost general-purpose sealing where standard O-rings are sufficient
How Engineers Usually Narrow Material Choices
Most projects do not start with a part number. They start with media, temperature, pressure, motion, and compliance requirements. These shortcuts get you to the right material family faster.
Oil, fuel, and hydraulics
Start with NBR for cost-sensitive petroleum service, move to HNBR for tougher mechanics, or FKM for higher heat and aggressive fuels.
Water, steam, and outdoor duty
EPDM and CR cover the common wet-service and weather-exposed cases, with AFLAS stepping in when steam, amines, or sour gas become severe.
Food, pharma, and clean processing
VMQ and FEP encapsulated seals are the usual short list when purity, washdown, and FDA-oriented service matter more than price.
Extreme chemicals and temperature
PTFE, FFKM, and spring-energized PTFE seals cover the edge cases where standard elastomers lose elasticity or fail chemically.
Material Comparison
| Material | Temp Range | Best For | Cost Index | Hardness |
|---|---|---|---|---|
| NBR | -40C to +120C | Petroleum oils, hydraulic fluids, fuels | $ | 40-90 Shore A |
| HNBR | -40C to +150C | Sour gas, automotive, high-pressure hydraulics | $$$ | 50-90 Shore A |
| FKM | -20C to +200C | High temperature, chemicals, aggressive fuels | $$$$$ | 60-90 Shore A |
| EPDM | -50C to +150C | Water, steam, HVAC, outdoor/UV exposure | $$ | 40-90 Shore A |
| VMQ | -60C to +230C | Food/pharma, extreme temperatures, static seals | $$$ | 20-80 Shore A |
| PTFE | -200C to +260C | Universal chemical resistance, static seals | $$$$ | 55-65 Shore D |
| FFKM | -15C to +325C | Extreme chemicals, high temp, semiconductor | $$$$$$ | 65-90 Shore A |
| PU | -35C to +80C | High-pressure hydraulics, pneumatics, dynamic seals | $$$ | 60-95 Shore A |
| CR | -40C to +120C | Refrigerants, marine, outdoor/HVAC | $$ | 40-90 Shore A |
| AFLAS | -5C to +230C | Steam, sour gas, caustic chemicals, amines | $$$$$ | 60-90 Shore A |
| FEP Encapsulated | -60C to +260C | Universal chemical resistance, food/pharma | $$$$$ | 70-90 Shore A |
| Rubber O-Rings | -60C to +200C | Hydraulic, fuel, water and static groove sealing | $$ | 40-90 Shore A |
| Metal O-Rings | -270C to +800C | Extreme temperature, vacuum, high pressure, cryogenic | $$$$$$ | 316L / Inconel |
| Rubber Gaskets | -200C to +260C | Flanges, manways, enclosures, custom flat seals | $$ | 30-90 Shore A |
| Kits | -60C to +325C | Maintenance, MRO, field service, prototyping | $$$ | Mixed |
| Spring Seals | -253C to +300C | Aggressive chemicals, vacuum, cryogenic and low-friction dynamic sealing | $$$$$$ | Spring + PTFE jacket |
Material Property Matrix
Indicative ratings on a 1–5 scale where 5 = best in class. Use this matrix to narrow material candidates before verifying with the Chemical Compatibility tool.
| Material | Tensile Strength | Elongation | Oil Resistance | Chemical Resistance | Max Temp | Relative Cost |
|---|---|---|---|---|---|---|
| NBR | 3 | 4 | 4 | 2 | 3 | 1 |
| HNBR | 4 | 4 | 4 | 3 | 4 | 3 |
| FKM | 3 | 3 | 5 | 4 | 4 | 5 |
| EPDM | 3 | 4 | 1 | 3 | 3 | 2 |
| VMQ | 2 | 5 | 1 | 2 | 4 | 3 |
| PTFE | 2 | 2 | 5 | 5 | 4 | 4 |
| FFKM | 3 | 3 | 5 | 5 | 5 | 6 |
| PU | 5 | 4 | 3 | 2 | 2 | 3 |
| CR | 3 | 4 | 2 | 2 | 3 | 2 |
| AFLAS | 3 | 3 | 3 | 4 | 4 | 5 |
| Rubber Gaskets | 3 | 4 | 3 | 3 | 3 | 2 |
1 = Poor / Low, 3 = Moderate / Medium, 5 = Excellent / Extreme. Cost scale: 1 = lowest, 6 = premium.
Indicative only — verify for your specific fluid and operating conditions.
Need Help Selecting a Material?
Use our material selector tool or contact our engineers for a recommendation.
Frequently Asked Questions
What are the common materials for O-rings?
The five most common O-ring materials are NBR (Nitrile), FKM (Viton/Fluorocarbon), EPDM, VMQ (Silicone) and PTFE. NBR is the most widely used for petroleum-based fluids. FKM is specified for high-temperature and chemical-resistant applications. EPDM is preferred for water and steam service. Silicone covers extreme temperatures and food/pharma applications. PTFE provides universal chemical resistance for static sealing.
Which O-ring material lasts the longest?
FKM typically outlasts NBR in high-temperature or chemically aggressive environments, while PTFE is virtually unaffected by chemical degradation. Service life depends entirely on matching the material to the application—for a given correct application, all materials have comparable service lives of years to decades under proper conditions.
Can I use one O-ring material for all applications?
No, no single material covers all applications. NBR is incompatible with steam and ozone. EPDM fails in oil. FKM is unsuitable for steam and ketones. PTFE lacks elasticity for dynamic sealing. Material selection must match the specific fluid, temperature and application type.
What is the difference between Viton and FKM?
Viton is a Chemours brand name for fluorocarbon elastomer; FKM is the generic ISO/ASTM designation for fluorocarbon rubber. All Viton compounds are FKM, but other manufacturers also produce FKM under different trade names.
What O-ring material is FDA approved?
FDA-compliant O-ring grades are available in EPDM, VMQ (Silicone) and PTFE under 21 CFR 177.2600 and 177.1550. Standard NBR compounds are not FDA compliant. When ordering for food or pharmaceutical contact applications, explicitly specify FDA grade and request the compliance certificate.