Rubber O-Rings
NBR, EPDM, silicone, neoprene and FKM toroidal seals. Standard AS568 and ISO 3601 sizes plus custom rubber o rings from drawing.
Overview
Rubber O-Ring Materials
NBR Rubber O-Rings
Nitrile / Buna-N rubber o rings for oil, fuel, hydraulic fluid and general industrial service. The most cost-effective choice for petroleum-based media.
Best for: Hydraulics, fuel systems, gearboxes, oil pans
EPDM Rubber O-Rings
Ethylene propylene rubber o rings for water, steam, brake fluid, glycol and outdoor UV exposure. Not compatible with petroleum oils.
Best for: Water treatment, HVAC, steam, solar thermal
Silicone Rubber O-Rings
VMQ rubber o rings for food, medical, pharmaceutical and high-temperature static sealing. FDA and USP Class VI grades available.
Best for: Food equipment, medical devices, dry heat
Neoprene Rubber O-Rings
Chloroprene rubber o rings with balanced ozone, weather and refrigerant resistance. Moderate oil resistance for general-purpose outdoor service.
Best for: Refrigeration, marine, HVAC, outdoor cabinets
FKM Rubber O-Rings
Fluoroelastomer / Viton rubber o rings for aggressive fuels, hot oil and chemicals. Continuous service up to +200°C.
Best for: Chemical processing, automotive fuel, hot oil
Material Properties
| Material | Properties | Best For |
|---|---|---|
| NBR 70 Shore A | −40°C to +120°C; excellent oil and fuel resistance | General hydraulics and fuel systems |
| EPDM 70 Shore A | −50°C to +150°C; water, steam, ozone and UV resistant | Water and outdoor service |
| VMQ 60 Shore A | −60°C to +200°C; FDA grades; poor petroleum resistance | Food, medical and high-temperature static seals |
| CR 70 Shore A | −40°C to +120°C; ozone, refrigerant and weather resistant | Refrigeration and marine |
| FKM 75 Shore A | −20°C to +200°C; high temperature and broad chemical resistance | Chemical and hot fuel service |
Standards & Sizes
Rubber o rings are manufactured to international size standards. Specify the standard and dash number, or provide ID and cross-section for custom sizes.
- AS568 inch dash numbers
- ISO 3601 metric sizes
- JIS B 2401
- DIN 3771
- Custom ID / CS from drawing
Sizing
Size rubber o rings by inner diameter (ID) and cross-section (CS). Standard AS568 and ISO 3601 sizes cover most industrial groove designs; custom sizes are cut or molded to order.
AS568 (inch)
- • 0.070 in
- • 0.103 in
- • 0.139 in
- • 0.210 in
- • 0.275 in
ISO 3601 / Metric
- • 1.78 mm
- • 2.62 mm
- • 3.53 mm
- • 5.33 mm
- • 6.99 mm
Custom
- • Any ID / CS from drawing
- • No mold fees on circular profiles
Rubber O-Ring vs Rubber Gasket
Choose the seal geometry that matches your joint design.
| Feature | Rubber O-Ring | Rubber Gasket |
|---|---|---|
| Seal geometry | Toroidal — sits in a groove | Flat — sits between flanges |
| Joint type | Grooved gland required | No groove needed |
| Pressure capability | Higher with proper gland design | 20–50 bar static typical |
| Best for | Hydraulics, fuel, dynamic/low-speed motion | Large flanges, manways, enclosures |
| Reusability | Single use after compression | Single use after compression |
Applications
Hydraulics & Pneumatics
Cylinder glands, valve bodies, pump ports, manifold face seals
Automotive & Transportation
Fuel injectors, oil pans, cooling systems, brake components
Food & Pharmaceutical
Static seals on processing equipment, washdown fittings, autoclaves
Frequently Asked Questions
What is a rubber o ring?
A rubber o ring is a toroidal elastomer seal used in a machined groove to block fluid or gas leakage. It is the most common seal type in hydraulics, automotive, aerospace and industrial equipment.
What is the difference between a rubber o ring and a rubber gasket?
A rubber o ring is toroidal and seals inside a groove; a rubber gasket is flat and seals between bolted flange faces. O rings handle higher pressures in groove designs; gaskets work without grooves on large flat joints. See our [O-ring vs gasket comparison](/blog/o-ring-vs-gasket-vs-seal/).
Which rubber o ring material should I choose?
NBR for oil and fuel, EPDM for water and steam, VMQ silicone for food and high temperature, CR neoprene for refrigeration and outdoor, FKM for chemicals and heat.
Do you supply custom rubber o rings?
Yes. Custom rubber o rings are available in any inner diameter and cross-section. Standard circular profiles have no mold fees. Provide a drawing, sample or dimensions for a quote.
What standards do your rubber o rings follow?
We manufacture to AS568, ISO 3601, JIS B 2401 and DIN 3771. Custom sizes are made to drawing.
What is a nitrile rubber o ring?
A nitrile rubber o ring is an NBR/Buna-N seal with excellent resistance to petroleum oils, fuels and hydraulic fluids. It is the most common material for general industrial and automotive use.
Can rubber o rings be used for dynamic sealing?
Rubber o rings work well for slow rotary, oscillating and reciprocating motion when the gland is designed for dynamic service and the material is matched to the media and speed. High-speed dynamic applications may need specialized seals.
What is the temperature range of a rubber o ring?
It depends on material. NBR −40°C to +120°C, EPDM −50°C to +150°C, VMQ −60°C to +200°C, CR −40°C to +120°C, FKM −20°C to +200°C.