Buna-N Nitrile O-Ring for Grooved ASA 7.5 / ANSI 3 Flange

This is an elastomer Buna-N Nitrile O-Ring for a grooved ASA 7.5 / ANSI 3 flange. The O-ring's width is 0.120 in. and its I.D. is 4.625 in. Used to mate an ASA 7.5 / ANSI 3 grooved flange with an ASA 7.5 / ANSI 3 smooth (non-grooved) flange.

Buna-N, also known as nitrile, is less expensive than either Viton or silicone O-ring material. Buna O-rings exhibit excellent resistance to all petroleum-based oils and fuels, as well as water, various alcohols, silicone greases, and hydraulic fluids. Buna also displays good tear resistance and non-polar solvent resistance. Buna O-rings can be used in rough vacuum systems and are rated for high vacuum to 1 x 10-8 Torr. Buna has a lower high temperature limit of about 120°C, but can effectively seal down to -30°C. Buna can be a cost effective seal solution when higher temperature bakeout is not required. The permeability of Viton does not allow it to be used for ultra-high vacuum applications.

ASA flanges are available with a smooth or grooved face, rotatable or non-rotatable, bored or non-bored, and are named for the outer diameter of the flange, from 4.25 to 19 inches. The ANSI name for the same flange size corresponds to the nominal tubing size that can be welded to it, and ranges from 1 to 12 inches in diameter.

ASA / ANSI flanges were originally used for steam pipes but have now been adapted to vacuum. Diffusion pumps, roots blowers, cryopumps and large rotary piston pumps are some examples of vacuum pumps where these flanges are used. When sealed together with O-rings made of Viton, Buna or Silicone, they are capable of achieving vacuum pressures as low as 1x10^-8 Torr. We have a complete line of ASA flanges, O-rings, and bolt sets to fit your most demanding needs.