Compounds for Nitrile O-Rings (Buna n)

Nitrile (buna n) is a copolymer of butadiene and acrylonitrile, a compound that is commonly used in o-rings. It is the acrylonitrile that brings the strong resistant to petroleum products to the combination. As more acrylonitrile is put into the mixture of the two components, the resistance of the nitrile o-rings to petroleum products increases. Unfortunately, at the same time, the low temperature flexibility of the nitrile o-rings decreases with more acrylonitrile. Thus, compounding nitrile (buna n) becomes a balancing act. If one wants good flexibility at low temperatures, some hydrocarbon fuel and petroleum oil resistance at high temperatures will have to be sacrificed.

Because of the resistance to fuel and oil, and the reasonable cost, more o-rings are made from nitrile (buna n) than any other elastomer. In addition to use with petroleum oils and fluids, nitrile o-rings are used for cold water, silicone greases and oils, Di-ester base lubricants and ethylene glycol base fluids. They do not do well with ozone, sunlight and exposure to weather.

Sometimes knowing exactly which compound should go into the nitrile o-rings for your application is difficult. We are happy to talk about your situation and help you solve sealing problems.

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