KF40-Flanged Components and Accessories


  • Quickly Connect to KF40 Vacuum Systems
  • Fiber Feedthroughs for Ultra-High Vacuum
  • Wing Nut Clamps and O-Ring Carriers

Application Idea

The MV11L05 Vacuum-Compatible Multimode Patch Cable connected to the VK4H1S Fiber Feedthrough KF40 Flange using the ADASMAV Vacuum-Compatible Mating Sleeve.

VK4L6S

KF40 SMA Fiber Feedthrough Flange, Ø600 µm Core

KF40CP

KF40 Blank Flange

KF40CR-F

KF40 Fluorocarbon
O-Ring Carrier

VK4F1S

KF40 Fiber Feedthrough Flange, Ø100 µm InF3 Fiber

Related Items


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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.

Our Ultra-High-Vacuum-Compatible Fiber Feedthrough KF40 Flanges allow for optical coupling into ultra-high-vacuum (UHV) systems down to 10-8 Torr using SMA905-terminated fiber patch cables and mating sleeves. We offer high OH fiber feedthroughs with a wavelength range of 200 - 1200 nm, InF3 fiber feedthroughs with a wavelength range of 0.3 - 5.5 µm, and low OH fiber feedthroughs with a wavelength range of 400 - 2400 nm. The low and high OH fiber feedthroughs feature hermetically sealed multimode step-index fibers with Ø100 µm, Ø200 µm, Ø400 µm, or Ø600 µm cores. Our InF3 fiber feedthroughs have a hermetically sealed multimode step-index fiber with a Ø100 µm core.

These fiber feedthroughs can be mated to a vacuum system using wing nut clamps and O-ring carriers. 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.

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.

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.

KF40 Flange Fiber Feedthroughs, 200 - 1200 nm


Click to Enlarge

Click for Data
This attenuation data was calculated as a function of wavelength for the fibers used in the UHV high-OH fiber feedthrough KF40 flanges.
  • Construction Enables use at Vacuum Pressures Down to 1 x 10-8 Torr
  • Hermetically Sealed Multimode Step-Index Fiber
    • Ø100 µm, Ø200 µm, Ø400 µm, or Ø600 µm Core
    • High OH (200 - 1200 nm)
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Laser Welded Body; Adhesive-Free on Vacuum Side
  • Bake-Out can be Conducted Up to 250 °C 
  • KF40 Flange-Centering O-Ring Carrier and Wing Nut Clamp Sold Below

Our Ultra-High-Vacuum-Compatible High-OH Fiber Feedthrough KF40 Flanges allow for optical coupling into ultra-high-vacuum (UHV) systems using SMA905-terminated fiber patch cables and mating sleeves. Constructed using 304 stainless steel, every feedthrough is designed to be used within UHV systems down to 10-8 Torr. All materials meet the NASA outgassing standard ASTM E 595-77-84-90. Each feedthrough incorporates a hermetically sealed 0.22 NA step-index multimode optical fiber in a stainless steel shell, provides a low insertion loss of ≤2.3 dB, and can handle optical powers up to 1 W. The flanges are double vacuum bagged to help prevent contamination when transported into a cleanroom environment.

Ultra-High Vacuum Fiber Feedthrough KF40 Flange Cross-Section
Click to Enlarge

Ultra-High Vacuum Fiber Feedthrough KF40 Flange Cross-Section

The fiber feedthroughs feature male SMA905 connectors on both sides; mating sleeves may be used to connect fiber patch cables. For the side of the feedthrough that is inside of the vacuum environment, the ADASMAV vacuum-compatible SMA-to-SMA mating sleeve can be used to connect a vacuum-compatible patch cable.  

The laser-welded joints of these flanges provide sturdier construction than traditional adhesives and greatly minimize leak rate. In addition, the locations of these laser welds and the hermetic glass-to-metal seal ensure that only external, easy-to-clean surfaces are directly exposed to the vacuum. Since there is no epoxy on the vacuum side of the feedthrough, there is minimal contamination and gas load on the vacuum system.

These KF flanges are ISO-standardized vacuum fittings that can be mated to a vacuum system using a wing nut clamp and an O-ring carrier (sold below). 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. Please note that the O-ring carrier and wing nut clamp must be purchased separately. 

Item # Fiber Core Fiber Wavelength Range NA Vacuum Level Insertion Loss Max Optical Power Max Temperature Leak Rate
VK4H1S Ø100 µm High OH 200 - 1200 nm 0.22 ± 0.02 1 x 10-8 Torr ≤2.3 dB 1 W 250 °C ≤1 x 10-10 mbar⋅L/s
(Helium Standard)
VK4H2S Ø200 µm
VK4H4S Ø400 µm
VK4H6S Ø600 µm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
VK4H1S Support Documentation
VK4H1SFiber Feedthrough for KF40 Flange, High OH, Ø100 µm Core, 200 - 1200 nm, 0.22 NA, SMA
$422.30
Today
VK4H2S Support Documentation
VK4H2SFiber Feedthrough for KF40 Flange, High OH, Ø200 µm Core, 200 - 1200 nm, 0.22 NA, SMA
$422.30
Today
VK4H4S Support Documentation
VK4H4SFiber Feedthrough for KF40 Flange, High OH, Ø400 µm Core, 200 - 1200 nm, 0.22 NA, SMA
$422.30
7-10 Days
VK4H6S Support Documentation
VK4H6SFiber Feedthrough for KF40 Flange, High OH, Ø600 µm Core, 200 - 1200 nm, 0.22 NA, SMA
$422.30
Lead Time

KF40 Flange Fiber Feedthrough, 0.3 - 5.5 µm


Click to Enlarge

Click for Data
This attenuation data was calculated as a function of wavelength for the fiber used in the MIR fiber feedthrough KF40 flange.
  • Construction Enables use at Vacuum Pressures Down to 1 x 10-8 Torr
  • Hermetically Sealed Multimode Step-Index Fiber
    • Ø100 µm Core
    • InF3 MIR (0.3 - 5.5 µm)
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Bake-Out can be Conducted Up to 90 °C
  • KF40 Flange-Centering O-Ring Carrier and Wing Nut Clamp Sold Below

Our Ultra-High-Vacuum-Compatible MIR Fiber Feedthrough KF40 Flange allows for optical coupling into ultra-high-vacuum (UHV) systems using SMA905-terminated fiber patch cables and mating sleeves. Constructed using 304 stainless steel, every feedthrough is designed to be used within UHV systems down to 10-8 Torr. All materials meet the NASA outgassing standard ASTM E 595-77-84-90. Each feedthrough incorporates a hermetically sealed 0.26 NA step-index multimode optical fiber in a stainless steel shell, provides a low insertion loss of ≤2.3 dB, and can handle optical powers up to 1 W. The flanges are double vacuum bagged to help prevent contamination when transported into a cleanroom environment.

The fiber feedthrough features a male SMA905 connector on the vacuum-facing side and 17.78" (451.6 mm) long, ruggedized, hermetic, permanently attached, InF3 multimode fiber cable ending in a male SMA905 connector on the other. The ruggedized cable on the non-vacuum side provides additional length and allows direct connection to more devices, minimizing insertion loss. Note that this fiber cable cannot be removed.

This KF flange is a ISO-standardized vacuum fitting that can be mated to a vacuum system using a wing nut clamp and an O-ring carrier (sold below). 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. Please note that the O-ring carrier and wing nut clamp must be purchased separately. 

Item # Fiber Core Fiber Wavelength Range NA Vacuum Level Insertion Loss Max Optical Power Max Temperature Leak Rate
VK4F1S Ø100 µm MIR (InF3) 0.3 - 5.5 µm 0.26 ± 0.02
@ 2.0 µm
1 x 10-8 Torr ≤2.3 dB 1 W 90 °C (Bake Out)
75 °C (Operating)
≤1 x 10-10 mbar⋅L/s
(Helium Standard)
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
VK4F1S Support Documentation
VK4F1SFiber Feedthrough for KF40 Flange, InF3 Multimode Fiber, Ø100 µm Core, 0.3 - 5.5 µm, 0.26 NA, SMA
$1,230.00
Today

KF40 Flange Fiber Feedthroughs, 400 - 2400 nm


Click to Enlarge

Click for Data
This attenuation data was calculated as a function of wavelength for the fibers used in the UHV low-OH fiber feedthrough KF40 flanges.
  • Construction Enables use at Vacuum Pressures Down to 1 x 10-8 Torr
  • Hermetically Sealed Multimode Step-Index Fiber
    • Ø100 µm, Ø200 µm, Ø400 µm, or Ø600 µm Core
    • Low OH (400 - 2400 nm)
  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Laser Welded Body; Adhesive-Free on Vacuum Side
  • Bake-Out can be Conducted Up to 250 °C
  • KF40 Flange-Centering O-Ring Carrier and Wing Nut Clamp Sold Below

Our Ultra-High-Vacuum-Compatible Low-OH Fiber Feedthrough KF40 Flanges allow for optical coupling into ultra-high-vacuum (UHV) systems using SMA905-terminated fiber patch cables and mating sleeves. Constructed using 304 stainless steel, every feedthrough is designed to be used within UHV systems down to 10-8 Torr. All materials meet the NASA outgassing standard ASTM E 595-77-84-90. Each feedthrough incorporates a hermetically sealed 0.22 NA step-index multimode optical fiber in a stainless steel shell, provides a low insertion loss of ≤2.3 dB, and can handle optical powers up to 1 W. The flanges are double vacuum bagged to help prevent contamination when transported into a cleanroom environment.

Ultra-High Vacuum Fiber Feedthrough KF40 Flange Cross-Section
Click to Enlarge

Ultra-High Vacuum Fiber Feedthrough KF40 Flange Cross-Section

The fiber feedthroughs feature male SMA905 connectors on both sides; mating sleeves may be used to connect fiber patch cables. For the side of the feedthrough that is inside of the vacuum environment, the ADASMAV vacuum-compatible SMA-to-SMA mating sleeve can be used to connect a vacuum-compatible patch cable.  

The laser-welded joints of these flanges provide sturdier construction than traditional adhesives and greatly minimize leak rate. In addition, the locations of these laser welds and the hermetic glass-to-metal seal ensure that only external, easy-to-clean surfaces are directly exposed to the vacuum. Since there is no epoxy on the vacuum side of the feedthrough, there is minimal contamination and gas load on the vacuum system.

These KF flanges are ISO-standardized vacuum fittings that can be mated to a vacuum system using a wing nut clamp and an O-ring carrier (sold below). 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. Please note that the O-ring carrier and wing nut clamp must be purchased separately. 

Item # Fiber Core Fiber Wavelength Range NA Vacuum Level Insertion Loss Max Optical Power Max Temperature Leak Rate
VK4L1S Ø100 µm Low OH 400 - 2400 nm 0.22 ± 0.02 1 x 10-8 Torr ≤2.3 dB 1 W 250 °C ≤1 x 10-10 mbar⋅L/s
(Helium Standard)
VK4L2S Ø200 µm
VK4L4S Ø400 µm
VK4L6S Ø600 µm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
VK4L1S Support Documentation
VK4L1SFiber Feedthrough for KF40 Flange, Low OH, Ø100 µm Core, 400 - 2400 nm, 0.22 NA, SMA
$422.30
Today
VK4L2S Support Documentation
VK4L2SFiber Feedthrough for KF40 Flange, Low OH, Ø200 µm Core, 400 - 2400 nm, 0.22 NA, SMA
$422.30
Today
VK4L4S Support Documentation
VK4L4SFiber Feedthrough for KF40 Flange, Low OH, Ø400 µm Core, 400 - 2400 nm, 0.22 NA, SMA
$422.30
Today
VK4L6S Support Documentation
VK4L6S Fiber Feedthrough for KF40 Flange, Low OH, Ø600 µm Core, 400 - 2400 nm, 0.22 NA, SMA
$422.30
Lead Time

KF40 Flange-Centering O-Ring Carrier and Wing Nut Clamp

Item # Included O-Ring Dimensions
OD ID Thickness
KF40CR-F 2.05" 1.65" 0.20"
  • KF40CR-F Centering O-Ring Carrier for KF40 Flanges
    • Holds O-Ring in Place Between KF Flanges
    • Creates Vacuum Seal When Compressed Against KF Mating Surfaces
    • Includes Fluorocarbon O-Ring
  • KF40WNC Wing Nut Clamp for KF40 Flanges
    • Secures Two KF40 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 KF40 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 KF25 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
KF40CR-F Support Documentation
KF40CR-FCentering O-Ring Carrier for KF40 Flanges with Fluorocarbon O-Ring
$12.51
Today
KF40WNC Support Documentation
KF40WNCWing Nut Clamp for KF40 Flanges
$10.10
Today

Blank KF40-Flanged Caps

  • 304 Stainless Steel Construction for High Durability and Low Outgassing
  • Blocks Unused Vacuum Ports

Stainless steel KF40 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 KF25 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
KF40CP Support Documentation
KF40CPKF40 Blank Flange Cap
$24.60
Today