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ISO KF & LF Fittings


MDC Kwik-Flange™ ISO KF and Large-Flange™ ISO LF Tube Fittings are convenient “building-block” components. They offer great flexibility in the design and construction of high vacuum systems.


  • High Vacuum rated to1x10-8 Torr
  • Temperature rated to 200°C
  • Symmetric, non rotatable geometries
  • Rotatable Bolt Rings available for LF sizes.
  • Viton® or Buna-N® O-Rings
  • Standard matte finish
  • ISO compatible design for full range of KF and LF sizes, NW16 to NW500
Flanges 304ss
Tubing  304ss
Finish Standard matte finish
Vacuum Range

1x10-8 Torr

Fitting Leak Test 2x10-10 cc/ sec of He
Temp.Range Minimum Intermittent Sustained
Viton® -20°C   200°C 150°C
Buna-N® -20°C   100°C 80°C
Silicone -50°C   200°C   150°C  

All fittings are fabricated from type 304 stainless steel drawn and welded vacuum tubing. Flanges do not need to be rotatable since they are completely symmetric. If desired, Rotatable Bolt Ring Assemblies can be retrofitted to existing Claw-Clamp style flanges to add bolt holes to ISO LF fittings.

Reducers are used for a change in size of flanges within a single method of sealing, such as elastomer sealing of ISO KF and LF flanges.

Adapters are used to change from one method of sealing to another, such as elastomer seal ISO to metal seal CF.


Inch-Metric ISO Comparision

MDC O.D Inches ISO I.D. mm Inches
Kwik-Flange™ ISO KF
K075 0.75 NW16 16 0.63
K100 1.00 NW25 25 0.98
K150 1.50 NW40 40 1.57
K200 2.00 NW50 50 1.97

Large-Flange™ ISO LF 
L250 2.50 NW63 63 2.48
L300 3.00 NW80 80 3.15
L400 4.00 NW100 100 3.94
L600 6.00 NW160 160 6.30
L800 8.00 NW200 200 7.87
L1000 10.00 NW250 250 9.84
L1200 12.75 NW320 320 12.60
L1600 16.00 NW400 400 15.75
L2000 20.00 NW500 500 19.69

 Related Topics
 Kwik-Flange™ ISO KF Introduction 
 Large-Flange™ ISO LF Introduction 
 ANSI ASA Flanges Introduction