Choosing the Right O-Ring Materials for Your Application

When deciding on the right O-ring for your hydraulic system, you need the right product to tightly seal the complex connections in the pipes and tubes.

O-rings are manufactured to suit a broad range of applications. They consist of a variety of elastomers with diverse chemical and physical properties to accommodate all requirements. This O-ring material selection guide will examine each O-ring material's characteristics and compatibility. Consider these comparisons to help you make the right choice for your industry.

Buna Nitrile

Buna Nitrile is popular because of its reasonable cost and superior resistance to substances derived from petroleum, such as hydraulic fluids, silicone greases, alcohols and water.

These O-rings are used frequently in gasoline tanks and aircraft applications.

Ethylene-Propylene (EPDM)

EPDM  has excellent resistance to ultraviolet light, alkalis, solvents, heat, ozone, water, and steam. However, do not use EPDM materials in environments containing hydrocarbons like oil, grease and gasoline.

The most common uses for this material are in wastewater systems, medical devices, automotive, and similar challenging applications.

Polytetrafluoroethylene (PTFE)

Polytetrafluoroethylene (PTFE) O-rings are intended for use in harsh and abrasive settings where the temperature ranges are extreme. The material is most compatible with a range of solvents, including, isopropyl, acetone, methyl, and others. Additionally, it absorbs little and has low gas permeability.  However, pure PTFE O-rings are inflexible and challenging to apply because of the innate qualities of the substance. 

In order to provide users more flexibility, manufacturers resolve this issue by combining PTFE material with different fillers. This material is not advised for applications requiring compressions and O-Ring strain.

Pharmaceutical, food and medical industries frequently use PTFE rings.

Nitrile Butadiene Rubber (NBR)

NBR has a high resistance to petroleum and hydraulic fluids, oils and water. It is not advised for use with automotive brake fluids, strong acids, ketones, methanol and halogenated hydrocarbons.

This substance is commonly used in marine, military, off-road and aircraft fuel systems.

Silicone

Silicone O-rings feature some excellent qualities, including a strong UV and ozone radiation resistance, extended fatigue life and superior flexibility. These O-rings are not recommended for dynamic applications. The majority of ketones, most petroleum fluids, steam, and water, are not compatible with them because of their low abrasion resistance, low strength and excessive gas permeability.

The extremely wide working temperature range for silicon O-rings makes them an excellent material for applications in the automotive, electronics and aerospace industries.

Talk to a supplier for more information.