235 Buna-N Backup Ring, 90A Durometer, 3.131" ID, 0.118" Thick, Black (Pack of 25)

Key features

• Contoured Backup Ring made of Buna-N (Nitrile, NBR) for use with a variety of fluids and hydrocarbons
• Durometer (hardness) of 90A
• For use across a wide temperature range from -40 degrees F (-40 degrees C) to 212 degrees F (100 degrees C)
• Backup Rings provide added extrusion resistance in high pressure sealing situations
• 1 or 2 Backup Rings can be used per 1 O-ring, depending on the direction of pressure in the sealing application

This contoured backup ring is made of Buna-N (also called Nitrile or NBR), has a durometer of 90A, and is designed for use in a wide variety of sealing applications.Backup rings provide added extrusion resistance, and prevent damage to O-rings and seals when subjected to high pressures, larger extrusion gaps, and/or high temperatures. Depending upon the direction of pressure in the sealing application, you can either use 1 backup ring or 2 backup rings. If unsure, it is always best to use two backup rings per 1 O-ring.Buna-nitrile can have high tensile strength, resistance to abrasion, tear, and compression set resistance. It is acceptable for temperature applications between -30 degrees F (-34 degrees C) to 250 degrees F (121 degrees C). It is compatible for use with petroleum, HFA, HFB, and HFC fluids, vegetable oil, alcohol, acids, and aliphatic hydrocarbons. Buna-nitrile is vulnerable to acetone, ethers, esters, ozone, sunlight, and weathering, and should therefore not be used in ozone-generating electric motors, welding equipment, or in applications with exposure to UV light.The durometer hardness of this Buna backup ring is 90A. Durometers measure the hardness of a material a

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