This is an elastomer red silicone 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.

Silicone O-rings have one of the widest working temperature ranges of any elastomer O-rings. They are more heat resistant than Viton or Buna O-rings, and exhibit excellent flexibiliy and low compression set characteristics. Silicone O-rings are used in rough vacuum systems and rated for high vacuum to 1 x 10-8 Torr. Fittings with silicone O-rings can be repeatably subjected to bakeout temperatures up to 200°C. The permeability of silicone 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.