Centering Ring O-rings are often used in vacuum fittings to improve seal performance.
Centering rings, also known as quick flange fittings, are used to create vacuum-tight connections between two ISO flanges with matching outer diameters. They are inserted between the flange faces and secured with a clamp to form a vacuum seal. The ring contains a flexible rubber O-ring that's compressed between the flanges to create a leak-tight seal. These O-rings can be made from materials such as Viton® (FKM), Markez® (FFKM) or Silicone.
KF, NW, and ISO Centering Ring O-Ring Fitting Sizes
Centering Ring Fitting Size | Centering Ring O-Ring Size USA | Centering Ring O-Ring Metric Alternative | |||||
|---|---|---|---|---|---|---|---|
NW | KF | ISO2861-1 | AS568 USA Size NW | Cross Section MM (IN) | Inside Diameter MM (IN) | Cross Section MM (IN) | Inside Diameter MM (IN) |
| NW10 | KF10 | ISO10 | -312 | 5.33 (0.210) | 15.00 (0.600) | 5.00 (0.197) | 15.00 (0.600) |
| NW16 | KF16 | ISO16 | -314 | 5.33 (0.210) | 18.42 (0.725) | 5.00 (0.197) | 18.00 (0.706) |
| NW25 | KF25 | ISO25 | -320 | 5.33 (0.210) | 27.94 (1.100) | 5.00 (0.197) | 28.00 (1.102) |
| NW40 | KF40 | ISO40 | -326 | 5.33 (0.210) | 40.64 (1.600) | 5.00 (0.197) | 42.00 (1.653) |
| NW50 | KF50 | -330 | 5.33 (0.210) | 53.34 (2.100) | 5.00 (0.197) | 55.00 (2.165) | |
| NW63 | KF63 | -336 | 5.33 (0.210) | 72.39 (2.850) | 5.00 (0.197) | 75.57 (2.975) | |
| NW80 | KF80 | -340 | 5.33 (0.210) | 85.09 (3.350) | 5.00 (0.197) | 88.27 (3.475) | |
| NW100 | KF100 | -346 | 5.33 (0.210) | 104.14 (4.100) | 5.00 (0.197) | 107.32 (4.225) | |
| NW160 | KF160 | -361 | 5.33 (0.210) | 151.76 (5.975) | 5.00 (0.197) | 158.12 (6.225) | |
Centering Ring USA or Metric O-Ring sizes can be used effectively depending on the application and gland design
Centering Ring O-Ring Materials
Many other elastomeric compounds are available. Contact us for more information.
Centering Ring Materials
Have Questions About Your Specific Application?
Connect With an Expert
- Expert product, application and design assistance
- Trusted by 14,000+ customers
- Fast response (usually within hours)
Marco Rubber & Plastics is an industry leader in custom sealing solutions that go beyond the limits of catalog commodities. Since 1980, our solutions have delivered reliable, long-lasting success for customers worldwide. We offer the largest inventory of specialty and standard sealing solutions backed by best-in-class technology, service and support.
