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KF-Flanged Components and Accessories


  • Quickly Connect to KF16 or KF25 Vacuum Systems
  • Adapters for Small-Diameter Tubing
  • Wing Nut Clamps and O-Ring Carriers
  • Flange Blanks to Block Unused Ports

KF25C038

KF25 Flange to Ø0.375" Compression Fitting Adapter

KF25WNC

KF25 Wing Nut Clamp

Application Idea

A KF25C050 Compression Fitting is used to add an empty glass cell to a KF-compatible vacuum system.

KF25CR-F

KF25 Fluorocarbon
O-Ring Carrier

KF16G25E

KF16 Flange to G1/4" Thread Adapter

KF16CP

KF16 Blank Flange

KF16CR-F

KF16 Fluorocarbon
O-Ring Carrier

Related Items


Please Wait
The animation above illustrates how a vacuum seal is achieved using KF Flanges.

Features

  • Compatible with ISO 2861 Clamped-Type Quick-Release Couplings
  • Vacuum-Facing Parts Cleaned Ultrasonically
  • 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.

Thorlabs offers fittings to adapt KF25-flanged components to pipes with outer diameters of 0.250", 0.375", or 0.500" via a compression fitting. Thread adapters are also available to mate British Standard Pipe Parallel (BSPP) or double ferrule compression fittings to KF16 vacuum components. These adapters and other components can be mated to a vacuum system using wing nut clamps and O-ring carriers. Our wing nut clamps and O-ring carriers, as well as our blank caps are available in both KF16 and KF25 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.

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.

General Diagram of a KF25 Flange
Click to Enlarge

Thorlabs KF25 Flange Measurements
General Diagram of a KF16 Flange
Click to Enlarge

Thorlabs KF16 Flange Measurements

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 and 25 mm KF components and accessories. The dimensions of our flanges are shown in the diagrams to the right. 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.


Posted Comments:
Spectroscopist .  (posted 2019-05-09 09:34:50.377)
Great that Thorlabs gets vacuum components into the catalogue! Most suppliers of vacuum components have a lead time of one week -- perfect that parts can now be available the next day!
YLohia  (posted 2019-05-09 12:11:13.0)
Thank you for your feedback! We try to stock the majority of our catalog for the convenience of our customers.

KF16 Flange to G1/4" Thread Adapter


Click to Enlarge

The double ferrule fitting on Thorlabs' Herriott Cells (left) can be replaced with the KF16G25E vacuum flange adapter (right). Note that the leakage rate of the Herriott Cell is not guaranteed if the gas fitting is replaced or adjusted by the user.
  • Connect KF-Compatible Vacuum Systems to BSPP Components
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • External Flats Accept 14 mm (9/16") Wrench

The KF16 Flange to G1/4" External Threading Adapter allows vacuum systems to be connected to British Standard Pipe Parallel (BSPP) components. The interior diameter of our adapter is Ø9.0 mm (Ø0.35"). The included rubber gasket is pre-installed onto the part; removing the gasket is not recommended, as it may become damaged. The exterior flats for tightening accept a 14 mm (9/16") wrench.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
KF16G25E Support Documentation
KF16G25EKF16 Flange to G1/4" Straight Thread Adapter
$62.32
Today

KF16 Flange to Double Ferrule Compression Fitting Adapters


Click to Enlarge

KF16PC25 adapter shown with double ferrule compression fittings. The ferrules and compressing nut are not included with the KF16PC25 or KF16PC6/M.
Item # Compatible Pipe OD Thread Type
KF16PC25 1/4"  7/16"-20
KF16PC6/M 6 mm
  • Quickly Connect KF-Compatible Vacuum Systems to Double Ferrule Compression Fittings
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Hex Accepts 9/16" (14 mm) Wrench 

These adapters allow KF16 vacuum systems to be connected to double ferrule compression fittings, making them compatible with Swagelok®-brand fittings. The image to the right shows how the KF16PC25 adapter interfaces with compression fittings; note the ferrule, washer, and nut are not included in the purchase of a double ferrule compression adapter. The KF16PC25 adapter accepts Ø1/4" metal tubes, and the KF16PC6/M adapter accepts Ø6 mm metal tubes; the hex on each adapter accepts 9/16" (14 mm) wrenches.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
KF16PC25 Support Documentation
KF16PC25KF16 Flange to Ø1/4" Double Ferrule Compression Adapter
$54.85
5-8 Days
+1 Qty Docs Part Number - Metric Price Available
KF16PC6/M Support Documentation
KF16PC6/MKF16 Flange to Ø6 mm Double Ferrule Compression Adapter
$54.85
Today

KF25 Flange to Compression Fitting Adapters

Item # Compatible Pipe OD Included O-Ring Dimensions
OD ID Thickness Dash #a
KF25C025 0.250" 0.38" 0.24" 0.07" 010
KF25C038 0.375" 0.50" 0.36" 0.07" 012
KF25C050 0.500" 0.63" 0.49" 0.07" 014
  • Society of Automotive Engineers (SAE) Dash Number as Defined in Standard AS568: Aerospace Size Standard for O-rings
  • Quickly Connect Glass and Metal Pipes to KF-Compatible Vacuum Systems
  • Options for Pipe Outer Diameters (OD) of 1/4", 3/8", or 1/2"
  • 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. Each fitting contains an internal Viton fluoroelastomer O-ring. When the knurled cap of the fitting is hand tightened, the O-ring compresses and forms a seal around the inserted pipe. For best results, a thin layer of vacuum grease should be applied to the internal O-ring; along with helping to create a vacuum seal, this grease allows an inserted pipe to slide along the O-ring without catching and causing damage. The knurled cap should not be overtightened, as excessive force could cause O-ring buckling, leading to leaks. The sizes of the internal O-rings are given the table to the right. 

Viton is a registered trademark of The Chemours Company.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
KF25C025 Support Documentation
KF25C025KF25 Flange to Compression Fitting Adapter for Pipes with OD = 0.250"
$75.19
Today
KF25C038 Support Documentation
KF25C038KF25 Flange to Compression Fitting Adapter for Pipes with OD = 0.375"
$75.19
Today
KF25C050 Support Documentation
KF25C050KF25 Flange to Compression Fitting Adapter for Pipes with OD = 0.500"
$75.19
Today

Wing Nut Clamps for KF Flanges

  • Clamp KF-Flanged Components
  • Fast Hand Tightening; No Tools Required
  • For KF16 or KF25 Flange Sizes

Wing nut fastening clamps fit around an assembly of two KF flanges separated by an O-ring. The angled sides of the clamp compress the O-ring between the flanges, quickly creating a vacuum seal. These components only require hand tightening the wing nut (M5 x 0.8), without the need for additional tools, allowing parts to be quickly swapped in and out of a KF-flanged system.

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. 

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
KF16WNC Support Documentation
KF16WNCWing Nut Clamp for KF16 Flanges
$6.95
Today
KF25WNC Support Documentation
KF25WNCWing Nut Clamp for KF25 Flanges
$7.98
Today

KF Centering O-Ring Carriers

Item # Included O-Ring Dimensions
OD ID Thickness Dash #a
KF16CR-F 1.15" 0.73" 0.21" 314
KF25CR-F 1.52" 1.31" 0.21" 320
  • Society of Automotive Engineers (SAE) Dash Number as Defined in Standard AS568: Aerospace Size Standard for O-rings
  • Holds O-Ring in Place Between KF Flanges
  • Creates Vacuum Seal When Compressed Against KF Mating Surfaces
  • Includes Fluorocarbon O-Ring
  • For KF16 or KF25 Flange Sizes

O-ring carriers keep O-rings centered between KF flange components during the clamping process. Carriers are available in KF16 and KF25 sizes; each include a single fluorocarbon O-ring sized appropriately for the corresponding flange size.

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.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
KF16CR-F Support Documentation
KF16CR-FCentering O-Ring Carrier for KF16 Flanges with Fluorocarbon O-Ring
$6.95
Today
KF25CR-F Support Documentation
KF25CR-FCentering O-Ring Carrier for KF25 Flanges with Fluorocarbon O-Ring
$8.76
Today

Blank KF-Flanged Caps

  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Blocks Unused Vacuum Ports
  • KF16 and KF25 Flange Sizes

Stainless steel KF flange blank caps can be used to protect a vacuum assembly that is not attached to a vacuum system, block a port during leak testing, or to cap off a port that is not being used on a vacuum chamber body. 

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
KF16CP Support Documentation
KF16CPKF16 Blank Flange Cap
$16.22
Today
KF25CP Support Documentation
KF25CPKF25 Blank Flange Cap
$16.48
Today
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