KF16-Flanged Components and Accessories


  • Quickly Connect to KF16 Vacuum Systems
  • Adapters for Tubing Diameters from 6 mm to 3/4"
  • Wing Nut Clamps and O-Ring Carriers

KF16CR-F

KF16 Fluorocarbon O-Ring Carrier

KF16CP

KF16 Blank Flange

KF16PC25

KF16 Flange to Ø1/4"
Double Ferrule
Compression Adapter

KF16G25E

KF16 Flange to G1/4" Straight Thread Adapter

Application Idea

Replace the double ferrule fitting on Thorlabs' Herriott Cells with the KF16G25E Vacuum Flange Adapter to enable connections to KF16 vacuum systems.

KF16C025

KF16 Flange to Ø1/4"
Compression Adapter

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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. The parts featured below have KF16 flanges. We also offer components with KF25 and KF40 flanges. 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.

The adapters below can be used to mate British Standard Pipe Parallel (BSPP), glass or metal pipe compression fittings, or double ferrule compression fittings to KF16 vacuum components. These adapters are constructed from 304 stainless steel for high durability and low outgassing. Wing nut clamps, O-ring carriers, and blank caps are also available.

Video Insight: Working with KF (QR) Vacuum Flange Components
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.

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 dimensions of our flanges are shown in the diagrams below. 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.

General Diagram of a KF40 Flange
Click to Enlarge

Thorlabs KF40 Flange Measurements
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
Equivalent Sizes
Absolute Maximum
Inner Diametera
KF Size DN Size NW Size
16 mm KF16 DN16 NW16
25 mm KF25 DN25 NW25
40 mm KF40 DN40 NW40
  • The absolute maximum inner diameter is the inner diameter of the largest pipe that can be welded to the flange. The item's inner diameter is often smaller than the absolute maximum inner diameter.

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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 KF16-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. Each flange is shipped with a protective plastic cover.

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
$67.07
Today

KF16 Flange to Compression Fitting Adapters

Item # Compatible
Pipe OD
Included O-Ring Dimensions
OD ID Thickness Dash #a
KF16C025 1/4" 0.38" 0.24" 0.07" 010
KF16C050 1/2" 0.63" 0.49" 0.07" 014
KF16C075 3/4" 0.88" 0.74" 0.07" 018
  • 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 KF16-Compatible Vacuum Systems
  • Options for Pipe Outer Diameters (OD) of 1/4", 1/2", or 3/4"
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Internal Viton®* Fluoroelastomer O-Ring Included

KF16 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 in the table above. Each flange is shipped with a protective plastic cover.

*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 - Imperial Price Available
KF16C025 Support Documentation
KF16C025NEW!KF16 Flange to Compression Fitting Adapter for Pipes with OD = 1/4"
$80.92
Today
KF16C050 Support Documentation
KF16C050NEW!KF16 Flange to Compression Fitting Adapter for Pipes with OD = 1/2"
$80.92
Today
KF16C075 Support Documentation
KF16C075NEW!KF16 Flange to Compression Fitting Adapter for Pipes with OD = 3/4"
$100.00
Today

KF16 Flange to Double Ferrule Compression Fitting Adapter


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 KF16-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 

This adapter allows 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 front ferrule, back ferrule, and nut are not included in the purchase of a double ferrule compression adapter. The KF16PC25 (KF16PC6/M) adapter accepts Ø1/4" (Ø6 mm) metal tubes and the hex on the adapter accepts 9/16" (14 mm) wrenches. Each flange is shipped with a protective plastic cover.

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
$59.03
Today
+1 Qty Docs Part Number - Metric Price Available
KF16PC6/M Support Documentation
KF16PC6/MKF16 Flange to Ø6 mm Double Ferrule Compression Adapter
$59.03
Today

KF16 Flange-Centering O-Ring Carrier and Wing Nut Clamp

Item # Included O-Ring Dimensions
OD ID Thickness Dash #a
KF16CR-F 1.15" 0.73" 0.21" 314
  • Society of Automotive Engineers (SAE) Dash Number as Defined in Standard AS568: Aerospace Size Standard for O-rings
  • KF16CR-F Centering O-Ring Carrier for KF16 Flanges
    • Holds O-Ring in Place Between KF Flanges
    • Creates Vacuum Seal When Compressed Against KF Mating Surfaces
    • Includes Fluorocarbon O-Ring
  • KF16WNC Wing Nut Clamp for KF16 Flanges
    • Secures Two KF16 Flanges Separated by an O-Ring
    • Fast Hand Tightening; No Tools Required
This animation illustrates a step-by-step procedure for coupling KF flanges.

Thorlabs offers a centering O-ring and a wing nut fastening clamp for mating KF16 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 KF25 wing nut clamps and O-rings, as well as KF40 wing nut clamps and O-rings.

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
$7.48
Today
KF16WNC Support Documentation
KF16WNCWing Nut Clamp for KF16 Flanges
$7.48
Today

Blank KF16-Flanged Cap

  • 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 KF25 blank flange caps and KF40 blank flange caps.

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
$18.33
Today