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574-218 90A Duro Buna-N Rubber Dished Back-up Rings


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Min Qty:  6
  • Model: N8-90-218
  • 1128 in Stock
  • Fits O-Ring Size -218
  • 0.118" W X 1.266"ID X 0.05"HT
  • 2.998mm W X 32.157mm ID X 1.27mm HT
  • PDF Data Sheets

AS568-218 (0.118" W X 1.266"ID X 0.05"HT)

A backup ring, or anti extrision device, is used in both static and dynamic O-Ring sealing applications. These Buna- N 90 durometer backup rings feature one dished face, allowing an ideal contoured and uniform contact with the O-Ring, and a flat surface for facing the extrusion gap. The Buna-N backup ring material, unlike teflon, still allows slight material elasticity during installation.

Buna-N 90 Durometer Material Information:

Nitrile is also known as Buna-N or NBR, is a copolymer of Butadiene and Acrylonitirle. It is the most commonly used elastomer for sealing products. It has a temperature range of -40F to +250F and is exceptionally resistant to petroleum base oils and hydrocarbon fuels. Nitrile materials also exhibit excellent tensile strength and abrasion resistance properties. The material performs well with most dilute acids, silicone oils and lubricants and in water applications. It is not recommended for use with ketones, aromatic hydrocarbons and phosphate ester hydraulic fluids. More than 50% of the Orings sold are Nitrile Orings, commonly used in hydraulic/pneumatic motors, cylinders, pumps and valves.

Buna-N / Nitrile Recommended uses:

  • General purpose sealing.
  • Petroleum oils and fluids.
  • Gasoline
  • Hydraulic fluids
  • L.P. gases
  • Cold Water.
  • Silicone greases and oils
  • Di-ester base lubricants (MIL-L-7808).
  • Ethylene glycol base fluids (Hydrolubes)

Nitrile is not recommended for:

  • Halogenated hydrocarbons (carbon tetrachloride, trichloroethylene)
  • Nitro hydrocarbons (nitrobenzene, aniline)
  • Phosphate ester hydraulic fluids (Skydrol, Fyrquel, Pydraul).
  • Ketones (MEK, acetone)
  • Ozone
  • Sunlight, UV
  • Weather
  • Strong Acids Ozone
  • Automotive brake fluid

Compound Info:

  • A sulfur-cured, Nitrile compound for high pressure
  • Color: Black
  • Duro: 90
  • FDA: No
  • ASTM M1BG910

Operating temperature: -40° to +250°F


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