These ISO-K DN 630 blank flanges follow vacuum technology standards as described in DIN 28404 and ISO 1609. ISO-K fittings are quick to assemble using claw clamps (please see figure - click to enlarge) and can be connected together in any orientation. The claw clamp hooks into a ridged groove in the back side of the ISO-K flange. A centering ring which contains a rubber elastomeric O-ring is used to form the vacuum seal between the two flange faces. They are commonly used to build process vacuum plumbing and systems for industrial vacuum applications. The ISO standard sizes for large LF flanges are ISO-K DN 63, 80, 100, 160, 200, 250, 320, 400, 500, 630. These vacuum fittings are made of corrosive resistant 304L stainless steel. NOTE: Due to their heavy weight, these flanges are shipped via freight.