Vacuum flanges and fittings connect runs of pipe and tubing in vacuum or process gas systems to other tubing sections, pipes, hoses, valves, pumps, chambers or other vacuum components. Fittings cover many components that connect hoses, pipes and tubes for in-line, offset, multi-port, and mounting configurations. ISO flange systems with o-ring or metal gasket seals are commonly applied in high vacuum applications. Systems are typically configured with straight sections connected by fittings or specially formed connections and joints. Fitting construction and material specifications are application-dependent; user consultation with fitting suppliers is typical for optimization of component selection. Other common components often included with vacuum flanges and fittings are viewports, access caps, glass-to-metal adapter straps, access doors and isolators.

Component Choices for Vacuum Flanges and Fittings

Component choices for vacuum flanges and fittings include access cap or port covers, adapters, ball socket or spherical joint adapters, ceramic or metal adapters or isolators, glass to metal adapters, flexible or expansion couplings, union couplings, 4-way cross, 5-way cross, 6-way cube or cross, flange, flange assembly, flange clamp, flange centering ring, bulkhead flange, 45 degree elbow, 90 degree elbow, end cap or plug, full nipple, half nipple, “U” or 180 return, stub, tee, and viewport.  Fittings, flanges or stubs can be provided in the form of a solid blank.  Blanks can be machined to form a customized fitting. Blanks are also used to blank-off the end of a section of tube or cap a port on a chamber. Important flange system or fitting port specifications to consider include configuration, seal system, and connection or port type.  Configuration of vacuum flanges and fittings can be all ports of the same type, or multiple port types or adapters.  Common seal systems include metal seal, elastomeric face seal or o-ring, ISO-BF, ISO-CF, ISO-KF or ISO-QF, ISO-LF, ISO-MF, ANSI ASA, VCR of VCO, Conflat, Tri-Seal, Del-Seal, Pyraflat, RL, NPT male, or NPT female. Common connections or port types for vacuum flanges and fittings include compression fitting, hose barb or rib, quick disconnect, threaded, flare or fitting tube, flange, and weld or braze stub.

Flange Size Specifications

Common flange size specifications to consider when selecting vacuum flanges and fittings include ISO nominal size, flange outer diameter (OD), and flange bore or inner diameter (ID).  The ISO nominal size refers to the nominal bore size.  Choices for ISO nominal size range from NW 10 to NW 1000.  Typically, the flange bore is similar in size to the tube OD. Ratings and features include vacuum pressure range, operating or bake-out temperature, features and materials of construction.  The vacuum or pressure range can be rough or low (< 760, > 1 torr), medium (< 1, >10-3 torr), high vacuum (< 10-3, >10-8 torr), ultra-high vacuum (< 10-8 torr), and elevated pressures (> 760 torr). The maximum operating or bake-out temperature that the fitting, flange or vacuum component can be exposed to is important to consider.  Common features for vacuum flanges and fittings include non-magnetic, polished or electro-polished, integral window, low profile, mitered or high-conductance, reducing, rotatable, square or custom shape, and zero profile.  Common materials of construction for vacuum flanges and fittings include ceramic, copper, glass, carbon and alloy steel, stainless steel, plastic or PVC, aluminum, and brass or bronze.