These ISO to ASA adapter reducer vacuum fittings follow International Standards Organization (ISO) and ASA/ANSI standards. They have a flange sizes of NW-100 to ASA/ANSI 6 inch. ISO LF flanged vacuum fittings are commonly used to build process vacuum plumbing and systems for industrial applications. The fittings are quick to assemble using double claw or single clamps and a centering ring (please see top right figure - click to enlarge). This ASA/ANSI flange side has NO O-Ring Groove.

The primary dimension of the ASA/ANSI flange is the Outer Diameter O.D. whether the term ASA or ANSI is used. The Viton® centering ring for the ISO side requires a rubber/elastomeric o-ring for vacuum. The ISO standard sizes for large flanges are NW-63, NW-80, NW-100, NW-160, NW-200, NW-250, NW-320, NW-400, NW-500, NW-630. These vacuum flanges are made of stainless steel. See graphic chart below for mating of ISO LF and ASA/ANSI options.