Uploaded April 2022 | Updated September 2026, 2 hours ago
A vacuum connection between two KF flanged components is made by compressing an O-ring between the two flanges. Minimizing leak rates through this vacuum coupling requires the flat flange faces to be smooth and clean, as well as the O-rings to be malleable and undamaged. This video demonstrates methods for coupling and disconnecting KF flanged components and shares tips for handling, maintaining, and assembling these popular vacuum flanges. Vacuum systems that include KF flanges can generally support vacuum levels down to 10-8 Torr (1.33 x 10-8 mbar, 1.33 x 10-8 hPa). Note that while the flange type is identified as KF (or QR), flange sizes may be specified using functionally equivalent prefixes of KF, DN, or NW.
There are many benefits to using KF flanged components in vacuum systems, including a genderless design, standardized sizes, quick decoupling and reconnection times, and being relatively inexpensive. Many of these features are made possible by the elastomeric O-ring that serves as a gasket.
The effectiveness of the vacuum seal depends on several factors including the conditions of both flange faces and the O-ring, the compression applied to the O-ring, and the O-ring's history of temperature exposure and usage. Excessive amounts of compression (greater than 60%) and exposure to high temperatures increases the rate at which the O-ring develops compression set. Compression set is a term used to refer to permanent changes in the O-ring's shape, which includes stiffening of the elastomeric material. Inspecting the O-ring and flange surfaces as shown in the video, and then replacing damaged components and stiffened O-rings can optimize performance. The application of vacuum grease to an O-ring is also demonstrated, and guidance for determining whether or not to use vacuum grease is provided.
00:00 - Introduction
00:47 - Comments on Personal Protective Equipment
01:46 - Double Gloving and Removing Gloves
03:36 - Aluminum Foil Work Surface
04:19 - Components and Features of a KF Flange Assembly
05:51 - Specifying Flange Size
07:03 - O-Ring Temperature Sensitivity and Compression Set
08:21 - Storing KF Vacuum Components
09:46 - Inspect and Wipe Sealing Surfaces
13:22 - Couple Elbow and Pipe and Show Chamfered Edges
15:33 - Vacuum Grease
18:51- Couple Blank to Assembly
Key Components used in this Demonstration Include:
- KF25WNC Wing Nut Clamp: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220&pn=KF25WNC&YVI=21
- KF25CR-F O-Ring and Carrier: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220#15227&YVI=21
- KF25CP KF Blank Flange Cap: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220&pn=KF25CP&YVI=21
- Elbow and Straight KF25 Pipes: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220#15225&YVI=21
- BD8 Solvent Dispenser: thorlabs.com/newgrouppage9.cfm?objectgroup_id=330&pn=BD8&YVI=21
- Nitrile Gloves: thorlabs.com/newgrouppage9.cfm?objectgroup_ID=1453#9626&YVI=21
- KW32 Wipes: thorlabs.com/newgrouppage9.cfm?objectgroup_id=330&pn=KW32&YVI=21
For more photonics how-to videos, visit thorlabs.com/newgrouppage9.cfm?objectgroup_id=14062&YVI=21
A vacuum connection between two KF flanged components is made by compressing an O-ring between the two flanges. Minimizing leak rates through this vacuum coupling requires the flat flange faces to be smooth and clean, as well as the O-rings to be malleable and undamaged. This video demonstrates methods for coupling and disconnecting KF flanged components and shares tips for handling, maintaining, and assembling these popular vacuum flanges. Vacuum systems that include KF flanges can generally support vacuum levels down to 10-8 Torr (1.33 x 10-8 mbar, 1.33 x 10-8 hPa). Note that while the flange type is identified as KF (or QR), flange sizes may be specified using functionally equivalent prefixes of KF, DN, or NW.
There are many benefits to using KF flanged components in vacuum systems, including a genderless design, standardized sizes, quick decoupling and reconnection times, and being relatively inexpensive. Many of these features are made possible by the elastomeric O-ring that serves as a gasket.
The effectiveness of the vacuum seal depends on several factors including the conditions of both flange faces and the O-ring, the compression applied to the O-ring, and the O-ring's history of temperature exposure and usage. Excessive amounts of compression (greater than 60%) and exposure to high temperatures increases the rate at which the O-ring develops compression set. Compression set is a term used to refer to permanent changes in the O-ring's shape, which includes stiffening of the elastomeric material. Inspecting the O-ring and flange surfaces as shown in the video, and then replacing damaged components and stiffened O-rings can optimize performance. The application of vacuum grease to an O-ring is also demonstrated, and guidance for determining whether or not to use vacuum grease is provided.
00:00 - Introduction
00:47 - Comments on Personal Protective Equipment
01:46 - Double Gloving and Removing Gloves
03:36 - Aluminum Foil Work Surface
04:19 - Components and Features of a KF Flange Assembly
05:51 - Specifying Flange Size
07:03 - O-Ring Temperature Sensitivity and Compression Set
08:21 - Storing KF Vacuum Components
09:46 - Inspect and Wipe Sealing Surfaces
13:22 - Couple Elbow and Pipe and Show Chamfered Edges
15:33 - Vacuum Grease
18:51- Couple Blank to Assembly
Key Components used in this Demonstration Include:
- KF25WNC Wing Nut Clamp: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220&pn=KF25WNC&YVI=21
- KF25CR-F O-Ring and Carrier: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220#15227&YVI=21
- KF25CP KF Blank Flange Cap: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220&pn=KF25CP&YVI=21
- Elbow and Straight KF25 Pipes: thorlabs.com/newgrouppage9.cfm?objectgroup_id=15220#15225&YVI=21
- BD8 Solvent Dispenser: thorlabs.com/newgrouppage9.cfm?objectgroup_id=330&pn=BD8&YVI=21
- Nitrile Gloves: thorlabs.com/newgrouppage9.cfm?objectgroup_ID=1453#9626&YVI=21
- KW32 Wipes: thorlabs.com/newgrouppage9.cfm?objectgroup_id=330&pn=KW32&YVI=21
For more photonics how-to videos, visit thorlabs.com/newgrouppage9.cfm?objectgroup_id=14062&YVI=21
