O-Ring Materials & Kits: Selection Guide
Selecting the right O-ring material is the most important decision in seal specification. The wrong material fails rapidly, regardless of size or groove design. This overview covers the core elastomer families, specialty sealing options, and kit formats used in industrial, automotive, food, and chemical service.
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
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 | $$ | 40-90 Shore A |
| AFLAS | -5C to +230C | Steam, sour gas, caustic chemicals, amines | $$$$$ | 60-90 Shore A |
| FEP Encapsulated | -60C to +260C | Universal chemical resistance, food/pharma | $$$$$ | 70-90 Shore A |
| Kits | -60C to +325C | Maintenance, MRO, field service, prototyping | $$$ | Mixed |
| Spring Seals | -253C to +300C | Aggressive chemicals, vacuum, cryogenic and low-friction dynamic sealing | $$$$$$ | Spring + PTFE jacket |
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?
Service life depends entirely on matching the material to the application. FKM typically outlasts NBR in high-temperature or chemically aggressive environments. PTFE is virtually unaffected by chemical degradation. 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 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 grades are available in EPDM, VMQ (Silicone) and PTFE under 21 CFR 177.2600 and 177.1550. NBR standard compounds are not FDA compliant. When ordering for food or pharmaceutical contact applications, explicitly specify FDA grade and request the compliance certificate.