Nitrile and Viton (Fluorocarbon rubber) are the most commonly used O-ring materials in industry. What are the differences between the two and what applications are they best suited for? Nitrile vs Viton is not an either/or consumer choice. Nitrile and Viton O-rings both have very different properties, varying in terms of tensile strength, temperature range, abrasion resistance etc. Making an informed choice of O-ring for your application involves understanding the differences between the two and how to select the most suitable component.
Commercial grade nitrile O-rings are extremely versatile components and are used in many different hydraulic systems. They are all manufactured using acrylonitrile-butadiene (NBR), but contain their active ingredient in varying amounts. This changes the properties of the O-ring, with high nitrile content giving greater resistance to hydrocarbons and lower content imparting a greater temperature range. The strength of one is the weakness of the other. So high nitrile O-rings have the lowest temperature range, while low nitrile O-rings have only minimal tolerance for hydrocarbons.
High Nitrile Content
If your system uses hydrocarbon fuels, mineral or aromatic oils, then high nitrile O-rings will work well for you. They have a reasonable temperature range of -30°C to 110°C, although their performance is impaired at lower temperatures.
Medium Nitrile Content
These widely used O-rings give a great balance of hydrocarbon resistance and temperature flexibility. The temperature performance range is -40°C to 135°C for most varieties. Medium nitrile O-rings perform well in the presence of mineral oils but are not the best with petrochemical fuel. They are also vulnerable to exposure to ozone, which may cause cracks and tears. Choose these O-rings for general hydraulic seals and for use in low-temperature water systems. They are not suited for use in systems where acids, ketones, ozone, brake fluid and some halogenated or nitro hydrocarbons are present.
Low Nitrile Content
The lowest grade nitrile O-rings do not have a high resistance to hydrocarbons, although they will cope with some mineral oils. Their strength is in their flexible temperature range of -50°C to 110°C, which includes high performance at low temperatures. The O-rings are strong components with an above average resistance to abrasion and tears.
Suitable For: Most hydraulic seals, water-based systems, petroleum engines, mineral fluids.
Viton is a high-performance O-ring material made from fluoroelastomers, suitable for systems where extreme temperature or chemical resistance is needed. There are several different classes of Viton O-ring, each with varying attributes, but as a rule you can expect a temperature range of -20°C to 200°C. Viton O-rings perform well in the presence of solvents, most acids, petrochemical fuel and mineral oils.
Where a hard-working seal is required under challenging conditions, Viton O-rings fit the bill. They are frequently used in automotive and aerospace engines, manufacturing equipment and medical applications.
Viton O-rings are tough and resilient to corrosion, ozone and tears. They perform well across the temperature range and are very unlikely to fail. Specialist Viton grades are available with added resistance to rapid gas decompression.
Despite their strength and versatility, Viton O-rings are vulnerable to ketones, skydrol fluids, armines and anhydrous ammonia. Although they cope well with acids under most circumstances, they are not recommended for use with hydrofluoric and chlorosulfonic acid at higher temperature ranges.
Suitable For: Severe and high performance environments. Commonly used by defence manufacturers, aerospace and automotive industries, and the oil and gas sector.
Choosing The Right O-Ring
At BSCL we stock an extensive catalogue of both nitrile and Viton O-rings. Our components are manufactured to the highest quality and are guaranteed to perform well under the most testing of conditions. Finding the right O-ring for your application involves selecting the right size, material and characteristics: there are thousands of different components to choose from. To help you make the right choice, we have written a free O-Ring Guide, which you can download from our website by clicking here. If you have any other questions and would like to speak with one of our technical sales team, please give us a call on 01922 646 716.