HNBR O-Ring Material Description

Hydrogenated Nitrile (HNBR) o-rings, also known as Highly Saturated Nitrile (HSN), are made of a synthetic polymer that is obtained by saturating the double bonds in nitrile’s butadiene segments with hydrogen. This special hydrogenation process reduces many double bonds in main chains of NBR polymers. This process results in the superior heat, ozone, chemical resistance, and mechanical characteristics of HNBR over standard Nitrile. HNBR o-rings are available in 70, 80, and 90 durometers.

HNBR o-rings are preferable for use with petroleum-based oils and fuels, aliphatic hydrocarbons, vegetable oils, silicone oils and greases, ethylene glycol, water, and steam (up to 300ºF), and diluted acids, bases, and salt solutions. HNBR o-rings are not preferable for use with chlorinated hydrocarbons, ketones, ethers, esters, and strong acids.

Acrylonitrile Content

Just like NBR, there are three different levels of Acrylonitrile (ACN) content in different HNBR polymers. The ACN content can be varied from 17% to 49%. Lower ACN content gives better low-temperature properties but lesser resistance to fuels and polar lubricants. Higher ACN content gives inferior low-temperature properties but improves fuels and polar lubricant resistance. Standard HNBRs typically have 36% ACN content.

Cure System: Peroxide-Cured

HNBR o-rings are usually peroxide-cured but can also be sulfur-cured to improve flexible properties in dynamic systems. However, sulfur-curing will reduce the heat resistance and cause an inferior compression set.

HNBR O-Ring Compounds

Temp Range (F)
Data Sheet
HNBR70 70


-40 to +302 Heat/Chemical resistance
HNBR80 80


-40 to +302 Heat/Chemical resistance
HNBR90 90


-40 to +302 Heat/Chemical resistance
H90105 90


-67 to +302 Rapid gas decompression resistance, Low temperature resistance
H90104 90


-13 to +302 Rapid gas decompression resistance
HSN70 70


-40 to +303 Heat/Chemical resistance
HSN80 80


-40 to +303 Heat/Chemical resistance
HSN90 90


-40 to +303 Heat/Chemical resistance

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Preferred Environments to Use HNBR O-Rings

Performs Well In:

  • Petroleum based oils and fuels
  • Aliphatic hydrocarbons
  • Vegetable oils
  • Silicone oils and greases
  • Ethylene glycol
  • Dilute acids, bases, and salt solutions to moderate temperatures
  • Water and steam to 150ºC (300ºF)

Doesn't Perform Well In:

  • Chlorinated hydrocarbons
  • Ketones
  • Ethers
  • Esters
  • Strong acids