Rubber O‑Rings – Everything You Should Know

18.01.2026

Author: inż. Robert Piotrowski

WHAT ARE O-RINGS? WHAT ARE THEIR APPLICATIONS?

Rubber O-rings are sealing elements with a circular cross-section which, thanks to their elasticity and practical design, have a wide range of applications.

The dimensions of seals are highly diversified, which makes them perfectly suitable for sealing components of various sizes that are positioned relative to each other both in motion and at rest.

Check our O-rings in a store near Warsaw!

TYPES OF O-RINGS (by material):

The development of technology enables the production of new rubber compounds and thus allows their use according to specific requirements. See the classification of rubber rings according to the materials from which they can be manufactured.

NBR O-RINGS

They show resistance to temperatures ranging from -30°C to +90°C.

They are resistant, among others, to oils and greases, silicone oils and greases, hydraulic oils, vegetable and animal oils. They also show high resistance to hydraulic fluids (HFA, HFC), propane, butane (aliphatic hydrocarbons), as well as diluted acids and bases. Commonly referred to as: O-rings or rubber O-rings.

FKM / FPM / Viton® O-RINGS

They show resistance to temperatures ranging from -20°C to +210°C.

They are resistant to aromatic hydrocarbons contained in benzene, hydraulic oils, mineral and silicone oils, vegetable and animal oils, as well as mineral greases, silicone greases and ozone. They also show high resistance to UV radiation; propane, butane (aliphatic hydrocarbons), as well as oxygen, vacuum, fuels (also those containing methanol) and synthetic hydraulic fluids, which is why they are considered basic Viton seals.

EPDM O-RINGS

They show resistance to temperatures ranging from -40°C to +150°C.

EPDM O-rings are mainly characterized by resistance to alcohols, esters, ketones; formic and acetic acid (short-chain organic acids), hydrochloric acid (inorganic acids), as well as atmospheric factors, hot water and steam. They also show high resistance to ozone, UV radiation, alkalis, glycol-based brake fluids, and aging under atmospheric conditions. Commonly adopted in Poland as O-rings for air conditioning systems.

SILICONE / VMQ / MVQ O-RINGS

They show resistance to temperatures ranging from -50°C to +240°C and in high-temperature variants up to 300°C.

Silicone O-rings are FDA food-grade certified and hydrophobic, i.e. non-water-absorbing. Thanks to the use of VMQ material, they also become electrical insulators and seals resistant to ozone. They also show high resistance to water and aqueous solutions, saline solutions and high temperatures.

HNBR O-RINGS

They show resistance to temperatures ranging from -30°C to +150°C.

HNBR O-rings are designed for sealing in environments containing hydraulic oils or ozone. They are used in applications where abrasion resistance is of the greatest importance – they have increased abrasion resistance.

FEP/PFA O-RINGS

They show resistance to temperatures ranging from -60°C to +260°C.

FEP O-rings have an additional jacket made of PTFE, which increases the chemical resistance of the O-rings. The effect is positive: enhanced chemical resistance combined with mechanical properties. Jacketed O-rings are used for the most demanding applications, such as drilling platforms.

FEP O-rings are available in several variants. The outer layer is always made of PTFE, while the core may be made of a different rubber compound. Seals made of PFA are suitable up to +260°C, while FEP compounds allow operation up to +204°C. Standard rubber compounds for the core of FEP/PFA seals include: FKM, FPM, Viton®, EPDM, EPM, VMQ and Silicone. The combination of these compounds results in some of the most resistant O-rings. More information can be found here: FEP O-rings, often also referred to as PTFE jacketed O-rings. So, which O-rings are the strongest and most durable? Here they are:

FFKM O-RINGS | Kalrez®

They show resistance to temperatures ranging from -15°C to +316°C.

FFKM O-rings, i.e. rings made of perfluoroelastomer compounds, are the best O-rings available worldwide. To date, no better rubber compound than FFKM has been developed. This compound is dedicated to all kinds of HIGH-TECH solutions. The material is available in many variants, which allows for seals resistant to temperatures above 300°C, suitable for food contact, or with very high chemical resistance to oils, amines or crude liquid fuels. This resistance allows their use in liquid fuel processing plants, drilling platforms and even space shuttles. At the same time, such capabilities come at a cost, but they increase safety and reduce the number of technological downtimes.

Are you now able to identify the ideal rubber O-ring material for your application?
If you want to learn how to dimension O-rings, we invite you to our guide, which presents all measurement and dimensioning methods used on the Polish market. Find out what the individual markings for O-rings mean. Visit: How to dimension O-rings

If you need even more information about seals, we invite you to our latest guide: rubber O-rings guide