Products Home / Optomechanical Components / Vacuum Components / KF25-Flanged Components and AccessoriesKF25-Flanged Components and Accessories
- Quickly Connect to KF25 Vacuum Systems
- Adapters for Small-Diameter Tubing
- Straight, Elbow, and Tee Fittings Available
- Wing Nut Clamps and O-Ring Carriers
Application Idea
A KF25C050 Compression Fitting is used to add an empty glass cell to a KF-compatible vacuum system.
KF25WNC
KF25 Wing Nut Clamp
KF25E45
45° Elbow Fitting with KF25 Flanges
KF25C038
KF25 Flange to Ø0.38"
Compression Fitting Adapter
KF25T
Three-Way Tee Fitting with KF25 Flanges
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Features
- Compatible with ISO 2861 Clamped-Type Quick-Release Couplings
- Vacuum-Facing Parts Cleaned Ultrasonically
- All Parts Double-Vacuum Bagged
- To Request Other KF Flange Nominal Diameters, Please Contact Tech Support
KF flanges are ISO-standardized vacuum fittings that provide a vacuum seal by compressing a rubber O-ring between two mating surfaces. Also referred to as NW, QF, or DN flanges, KF flanges are ideal for quickly assembling vacuum systems thanks to their ease of use, maintenance, and reusability.
We offer KF25 Flange Compression Fitting Adapters to quickly connect glass and metal pipes to KF-compatible vacuum systems. For an application example using our KF25 Flanges and our empty glass cells, please see the Application tab. Options are available for connecting to pipes with imperial outer diameters from 1/4" to 1" and metric outer diameters from 6.0 mm to 25.0 mm. Please refer to Table G1.2 in the KF25 Flange to Compression Fitting Adapters for compatible imperial and metric tube sizes. We also offer KF25-flanged straight, elbow, and tee fittings for use in assembling vacuum systems. Our straight fittings are available in 50 mm, 100 mm, and 250 mm lengths. Our elbow fittings are available with either a 45° or 90° angle.
All of the KF25 Flange Compression Fitting Adapters and KF25 Flange Fittings are constructed from 304 stainless steel for high durability and low outgassing. These adapters and fittings are manufactured using internal welds by an automated laser welder that provides high quality and consistent welding. The internal welds eliminate any hard-to-evacuate air pockets in the part that an external weld might create.
Our wing nut clamps, O-ring carriers, and blank caps are available in KF16, KF25, and KF40 sizing. Key dimensions of these KF flanges can be found by visiting the KF Flange Sizes tab. Our in-house machine shop allows us to modify or customize components with any standard KF flange. To submit a request, please contact Tech Support.
An approach for working with KF flanges is demonstrated, and tips are shared for minimizing leak rates, extending lifetimes, and recognizing when to replace O-rings.
For best performance, a very thin coating of vacuum grease should be applied to any O-ring used in a KF system. This should be done by hand while wearing gloves, leaving just enough grease to cause the O-ring to shine. The O-ring and its mating surfaces should be visually inspected before installation to ensure there is no debris which may prevent proper contact and cause a leak. O-rings should be regularly inspected to spot dry rot, cracking, tearing, or accumulation of debris from normal operation. Replace any O-ring suspected of causing a leak.
| Quick Links | |||||
|---|---|---|---|---|---|
| Flange | Description | Flange | Description | Flange | Description |
| KF16 | G1/4" Thread Adapter | KF25 | Compression Fitting Adapters | KF40 | 200 - 1200 nm Fiber Feedthrough |
| Compression Fitting Adapters | Straight, Elbow, and Tee Fittings | 0.3 - 5.5 µm Fiber Feedthrough |
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| Double Ferrule Compression Fitting Adapter |
O-Ring Carrier & Wing Nut Clamps |
400 - 2400 nm Fiber Feedthrough |
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| O-Ring Carrier & Wing Nut Clamps |
Blank Flanged Caps | O-Ring Carrier & Wing Nut Clamps |
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| Blank Flanged Caps | - | Blank Flanged Caps | |||
KF Flange Sizes
KF flanges are defined by ISO 2861 Clamped-Type Quick-Release Couplings. This specification details the dimensions and tolerances for the five standard KF flange sizes: 10 mm, 16 mm, 25 mm, 40 mm, and 50 mm. These sizes are the nominal bore size of the flanged pipe. The name "KF" derives from the German phrase "Klein Flansche," literally translating to "small flange"; this name was used around the time of the flange's adoption by ISO and DIN, as flanges for pipes larger than 50 mm are more appropriately handled by flanges that deform metal gaskets to create a seal, like CF flanges.
Thorlabs offers from stock 16 mm, 25 mm, and 40 mm KF components and accessories. The general dimensions of our flanges can be seen by referencing Table 57A and Figure 57B. Our in-house machine shop allows us to modify or customize components with any standard KF flange. To submit a request, please contact Tech Support.
Click to Enlarge
Figure 57B For Thorlabs' KF Flange Measurements please see Table 57A.
| Table 57A Specifications | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Equivalent Sizes | Thorlabs' KF Flange Measurements | ||||||||||
| Absolute Maximum Inner Diametera |
KF Size | DN Size | NW Size | A | B | C | |||||
| 16 mm | KF16 | DN16 | NW16 | 1.18" (30.0 mm) | 0.12" (3.0 mm) | 0.10" - 0.11" (2.5 mm - 2.8 mm) |
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| 25 mm | KF25 | DN25 | NW25 | 1.58" (40.0 mm) | 0.12" (3.0 mm) | 0.10" - 0.11" (2.5 mm - 2.8 mm) |
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| 40 mm | KF40 | DN40 | NW40 | 2.17" (55.0 mm) | 0.12" (3.0 mm) | 0.11" (2.7 mm) | |||||
Creating a Vacuum Seal with a KF Flange
Thorlabs' KF25-Flanged components and accessories can be used to manage gas flow in and out of our empty borosilicate glass cells. Thorlabs' empty glass cells are terminated with one or two fill tubes that can be inserted into a compatible KF25 Series flange-to-compression-fitting adapter.
To input the glass cell into a KF25 vacuum system, follow the instructions below.
- Select a KF25 flange-to-compression-fitting adapter that is compatible with the fill tube diameter of the glass cell.
- Coat a cleaned and inspected KF25CR-F Centering O-Ring in vacuum grease and place it on a base post or pipe.
- Place the flange-to-compression-fitting adapter on top of the KF25CR-F Centering O-Ring and secure them with the KF25WNC wing nut clamp.
- Loosen and remove the knurled locking knob, O-ring, and seal sing of the flange-to-compression-fitting adapter so its mating surface can be inspected and the included O-ring can be coated in vacuum grease. This will create a vacuum seal when the cell is inserted into the system.
- Slide the open end of the glass cell tube through the top (side with the Thorlabs engraving) of the knurled locking knob, seal ring (with the counterbore seat for the O-ring facing the adapter body), and O-ring (in that order) of the flange-to-compression-fitting adapter.
- Slide the glass tube into the flange adapter body and then slide the O-ring, seal ring, and knurled locking knob down the tube onto the flange adapter body. Tighten the knurled locking knob by hand.
It is not recommended to insert the glass tube into a fully assembled KF Flange-to-compression-fitting adapter. The sharp edges of the glass tube may damage the O-ring thus causing the seal to fail.
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Click to Enlarge
Figure G1.1 Disassembled View of the KF25 Flange to Compression Fitting Adapter
- Quickly Connect Glass and Metal Pipes to KF-Compatible Vacuum Systems
- Options for a Variety of Pipe Outer Diameters (OD):
- 1/4" to 1" Imperial Sizes
- 6.0 mm to 25.0 mm Metric Sizes
- 304 Stainless Steel Construction for High Durability and Low Outgassing
- Internal Viton®* Fluoroelastomer O
-Ring Included
KF25 flanges with compression fittings mount smooth-surfaced pipes to vacuum systems, including metal tubes, such as those used for gas lines, or glass tubes like those found on our empty glass cells or fused silica optical ports. Each fitting contains an internal Viton fluoroelastomer
*Viton is a registered trademark of The Chemours Company.
| Table G1.2 Specifications | ||||||
|---|---|---|---|---|---|---|
| Item # | Compatible Pipe OD | Included |
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| Imperial | Metric | OD | ID | Thickness | Dash #a | |
| KF25C025 | 1/4" | 6.0 mm and 6.4 mm | 0.38" (9.6 mm) | 0.24" (6.1 mm) | 0.07" (1.8 mm) | 010 |
| KF25C031 | - | 8.0 mm | 0.44" (11.2 mm) | 0.30" (7.6 mm) | 0.07" (1.8 mm) | 011 |
| KF25C038 | 3/8" | 10.0 mm | 0.50" (12.8 mm) | 0.36" (9.2 mm) | 0.07" (1.8 mm) | 012 |
| KF25C050 | 1/2" | 13.0 mm | 0.63" (16.0 mm) | 0.49" (12.4 mm) | 0.07" (1.8 mm) | 014 |
| KF25C075 | 3/4" | 19.0 mm | 0.88" (22.4 mm) | 0.74" (18.8 mm) | 0.07" (1.8 mm) | 018 |
| KF25C100 | 1.00" | 25.0 mm | 1.13" (28.6 mm) | 0.99" (25.2 mm) | 0.07" (1.8 mm) | 022 |
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Click for Details
Figure G2.2 KF25E90 Elbow Fitting Dimensions
Click for Details
Figure G2.1 KF25E45 Elbow Fitting Dimensions
- Straight, Elbow, and Tee Fittings for KF25 Vacuum Systems
- Tube Diameters:
- Straight Fittings 0.87" (22.1 mm) ID, 0.99" (25.1 mm) OD
- Elbow and Tee Fittings 0.87" (22.1 mm) ID, 1.00" (25.4 mm) OD
- 304 Stainless Steel Construction for High Durability and Low Outgassing
We offer straight, elbow, and tee fittings with KF25 flanges for use when assembling vacuum systems. Details on the angles of the elbow fittings can be found by clicking on Figures G2.1 and G2.2. Each flange is protected with a plastic cover during shipping.
Zoom| Item # | Included O-Ring Dimensions | |||
|---|---|---|---|---|
| OD | ID | Thickness | Dash #a | |
| KF25CR-F | 1.52" | 1.10" | 0.21" | 320 |
- KF25CR-F Centering O-Ring Carrier for KF25 Flanges
- Holds O-Ring in Place Between KF Flanges
- Creates Vacuum Seal When Compressed Against KF Mating Surfaces
- Includes Fluorocarbon O-Ring
- KF25WNC Wing Nut Clamp for KF25 Flanges
- Secures Two KF25 Flanges Separated by an O-Ring
- Fast Hand Tightening; No Tools Required
Thorlabs offers a centering O-ring and a wing nut fastening clamp for mating KF25 flanges to a vacuum system. The angled sides of the wing nut clamp compress the O-ring between the flanges, quickly creating a vacuum seal. The wing nut clamp, which has M5 x 0.8 threads, requires only hand tightening, allowing parts to be quickly swapped in and out of a KF-flanged system.
For best performance, a very thin coating of vacuum grease should be applied to the O-ring before installation. This should be done by hand while wearing gloves, leaving just enough grease to cause the O-ring to shine. The O-ring and its mating surfaces should be visually inspected before installation to ensure there is no debris which may impede proper contact and cause a leak. O-rings should be regularly inspected to spot dry rot, cracking, tearing, or accumulation of debris from normal operation. Replace any O-ring that is suspected of causing a leak. Additionally, be aware that under vacuum pressure, the KF connection may undergo additional compression, causing the wing nut clamp to loosen. Some additional tightening may be performed, but be careful not to overtighten the clamp, as the wing nut may become difficult to remove or jammed when the system returns to atmospheric pressure. Do not remove a wing nut clamp while a system is under vacuum.
We also offer KF16 wing nut clamps and O-rings, as well as KF40 wing nut clamps and O-rings.
Zoom- 304 Stainless Steel Construction for High Durability and Low Outgassing
- Blocks Unused Vacuum Ports
Stainless steel KF flange blank caps can be used to protect a vacuum assembly that is not attached to a vacuum system, to block a port during leak testing, or to cap off a port that is not being used on a vacuum chamber body. Each cap is shipped with a protective plastic cover.
We also offer KF16 blank flange caps and KF40 blank flange caps.
KF25 Components and Accessories