Material Selection Of O-rings

- Feb 06, 2018-

The material used for the O-ring is nitrile rubber, carboxylic acid, fluororubber, EPR, HNBR, silicone rubber, CR, fluorocarbon silicone rubber, polyurethane, epichlorohydrin rubber, SBR, butyl rubber, natural rubber, ethylene/ethylpropionate rubber, polyacrylate rubber, etc. This article introduces several commonly used O-rings materials.

Nitrile Rubber (NBR)

Nitrile rubber is polymerized from acrylonitrile and butadiene, the higher the content of acrylonitrile, the better the resistance of hydrocarbon fuel oil, but the low temperature performance will be worse, the general use temperature range of -25 ~ 100℃. Nitrile rubber is currently one of the most commonly used rubber oil seals and O-rings.


● Good resistance to oil, water, solvents and anti-high pressure oil properties.

● With good resistance to compression, wear and extensibility.


● Not suitable for use in polar solvents such as ketones, ozone, nitro hydrocarbons, MEK and chloroform.

It is used to produce rubber parts, especially sealing parts for fuel tank, lubricating oil tank and fluid medium such as petroleum hydraulic oil, gasoline, water, silicon grease, silicone oil, diester lubricating oil and glycol type hydraulic oil. It is the most widely used rubber seal with the lowest cost.

Silicone Rubber (Si)

The main chain of silicone rubber is made up of silicon (-si-o-si). It has excellent heat resistance, cold resistance, ozone resistance and aging resistance. It has good electrical insulation performance. The tensile strength is less than that of the general rubber and has no oil resistance.


● Good flexibility

● Good resistance to neutral solvents

● Excellent heat resistance and cold resistance

● Excellent resistance to the erosion of ozone and oxide

● Excellent electrical insulation performance

● Good thermal insulation and heat dissipation


● It is not recommended for most concentrated solvents, oils, concentrated acids, and diluted sodium hydroxide.


The sealing parts or rubber parts can be used in appliances industry and the electronics industry, etc.

Fluoro Carbon Rubber (FPM)

Fluorine rubber has various types according to the content of fluorine (that is, the structure of the monomer). At present, the commonly used fluorine rubber is superior to silicone rubber in high temperature resistance, excellent chemical resistance, resistance to most oils and solvents (except ketones and esters), weather resistance and ozone resistance; poor cold resistance, general operating temperature range -20 to 250 ℃.


● Good heat resistance (up to 250℃).

● Resistance to most of the oil and solvents, especially all acids, aliphatic hydrocarbons, aromatic hydrocarbons and animal and plant oils.


● It is not recommended to be used for ketones, low molecular weight esters and mixtures of nitrite.

● It is not recommended for automobiles, locomotives, diesel engines and fuel systems.

 It is not recommended for seals used in chemical works.

Perfluoroelastomer (FFPM)


● Excellent heat resistance.

● Excellent chemical resistance.

● Low outgassing.

● Good anti-plasma properties.


● Low temperature resistance.

 High price of raw materials.

● High difficulty in production.

Perfluorinated products are widely used in the semiconductor industry and information-related industries. The range of applications includes PVC, CVD and etching processes in thin-film manufacturing and various high-vacuum sealing processes.