Compare Model Drawings, CAD & Specs Availability Price
Overpressure Centering Ring, NW50 Size ISO-KF Flange, Viton O-Ring
In Stock
In Stock
Overpressure Centering Ring, NW40 Size ISO-KF Flange, Viton O-Ring
In Stock
In Stock
Overpressure Centering Ring, NW25 Size ISO-KF Flange, Viton O-Ring
In Stock
In Stock


  • Component Type
    Overpressure Centering Ring Assembly
  • Series
    Series 31
  • Material
    Stainless Steel
  • Seal Material
  • Flange Type


Positive Pressure Applications

When vacuum system pressures are in the positive pressure range, it is recommended that over pressure rings are used. The ISO-KF flange over pressure rings are installed differently by size. The NW16, NW25, and NW40 ISO-KF over pressure rings are installed over the two ISO-KF flanges. The NW10 and NW50 ISO-KF over pressure rings are installed between the two flange faces. The clamp is installed around all items to secure the assembly.

ISO-KF Vacuum Flange Standard Dimensions

inch (mm)

The International Standards Organization has defined the interface dimensions of ISO-KF vacuum flanges allowing the interchanging of components that conform to the ISO-KF standard. The ISO-KF flange system provides is a modular building block method for creating a vacuum systems. Since component dimensions are standardized, elbows, tees, crosses or valves for a given flange size can be interchanged. The flanges are sexless and the seal is symmetrical allowing components to be rotated. By using ISO-KF standard components, vacuum system assembly is quick and cost effective.

Joining ISO-KF Vacuum Flanges

ISO-KF vacuum flange components are joined by inserting a centering ring seal between the two flange faces, then securing the assembly with a flange encompassing clamp. There are a variety of flange clamp choices available. The wing-nut flange clamp is hand tightened until metal contact is felt. The toggle flange clamp is convenient and easy to use and provides enough sealing force to fully compress the O-Ring, so that the flanges and the centering ring are metal to metal. The self-adjusting clamp locks in a positive method making it ideal when clamp must be removed frequently, like leak testing or gauge calibration. Bulkhead flange clamps attach an ISO-KF flange directly to a chamber or base plate. The two-part, bolted clamp fits over the flange with a centering ring assembly used between the flange and the opening.