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Del-Seal CF™ Metal Seal Flanges

MDC established its standing in the vacuum components world after becoming one of the first licensed manufacturers of Varian’s patented Conflat® metal-seal flange, known today to most MDC customers as the Del-Seal™ CF metal-seal flange.

Del-Seal™ CF flanges are 100% Conflat® compatible metal-seal flanges suitable for the most demanding UHV applications. Del-Seal™ CF metal seal flanges are available in a wide range of sizes that can accommodate 1/8" to 14" tube diameters. For tube sizes above 14 inches and up to 24 inches in diameter, MDC wire seal flanges are recommended.

Del-Seal™ CF Fittings

MDC Del-Seal™ CF fittings such as nipples, half nipples, reducer nipples, flexible nipples, elbows with 45° and 90° configurations, tees, reducer tees, crosses with four-, five- and six-way configurations, six-way cubes and multiport flange assemblies comprise the industry's largest selection of Del-Seal™ CF fitted vacuum components. If we do not have the product you seek, custom versions of most of these components can be quoted upon request.

Wire Seal Flanges

MDC Wire Seal Flanges provide a convenient method of metal-sealing large diameter vacuum chambers. These metal seal flanges pick up where the Del-Seal™ CF metal seal flanges leave off. They are available for tube sizes from 10 to 24 inch diameter, and only in a nonrotatable geometry. Because of their size, blank wire seal flanges are of significant weight. For applications restricted by weight limitations MDC offers blank wire-seal flanges with a dished-head construction which greatly reduces the flange’s overall weight.

An .080 inch cross-section diameter OFE copper wire gasket is compressed between male and female mating flanges. The beveled geometry of the sealing surfaces confine the flow of the crushed gasket material, causing it to fill minor imperfections in the seal area. See the wire seal flange cross-section diagram at the bottom of the previous page. Applications for the use of wire-seal flanges include bell jars, vacuum furnaces and a variety of other ultrahigh vacuum enclosures. As with Del-Seal™ CF flanges, these too can be used with elastomer gaskets for high vacuum applications.


Hybrid Adapters


Del-Seal™ CF

Del-Seal ™ CF Fittings

Nonrotatable and Rotatable Flanges

Nonrotatable and rotatable flanges are typically used in combination for bolt alignment purposes. Nonrotatable flanges are often referred to as fixed flanges. A nonrotatable flange is constructed of a single machined piece. Once nonrotatable flanges are welded in place their fastening bolt holes are fixed in position. The industry standard for positioning fixed flange bolt holes is to have bolt holes straddle a vertical centerline. Flanges fitted with leak test grooves are welded so that the groove is positioned on that vertical centerline. A rotatable flange is constructed of two concentric or coaxial components, these are referred to as the receiver and the insert. The receiver, or outer ring, contains the fastening bolt holes while the insert is the blank or bored center piece that contains the sealing knife edge and to which a mating tube is typically welded. The term “rotatable” pertains to the flange’s outer ring or receiver prior to the insertion of fasteners. The receiver is rotatable for the purpose of aligning bolt holes with fixed, nonrotatable mating flanges. Once the holes have been aligned and fasteners inserted, the flange is no longer rotatable. Fastening two rotatable flanges is not only difficult but also increases the possibility for damage to one or both of the mating flange knife edge seals. Caution should be exercised when fastening two rotatable flanges.

Del-Seal™ CF metal seal flanges are fitted with either clearance or threaded fastening bolt holes. Clearance holes are commonly referred to as through holes and threaded holes are commonly referred to as tapped holes. Tapped holes provide threads through the entire thickness of a flange. Exceptions to this include reducer flanges and cubes which are fitted with blind tapped holes. Blind tapped holes are drilled only part way through a flange and do not break through. Blind tapped holes are typically used where drilling through a component is not possible or desirable, like the direct tapping of a chamber wall, where breaking through would provide a leak path through the vacuum walls.