KF (QF) and ISO Flanges

ANCORP’s KF (QF) and ISO (LF) flanges are available in a variety of designs and materials for easy integration into high vacuum systems and components. Available flange types include bored weld flanges, blank flanges, and unbored stub flanges. All KF and ISO flanges are manufactured to ISO specifications to ensure 100% compatibility with other vacuum flange manufacturers’ components. ANCORP offers KF and ISO flanges in 304 stainless steel, 316 stainless steel, and 6061 aluminum.

 

KF Flanges (ISO-QF Quick Flanges)

KF flanges, also called QF or NW flanges, are used to form high vacuum connections in 1/2″ (QF10) to 2″ (QF50) diameter vacuum system tubing. KF flanges are sexless, infinitely rotatable, and fastened with quick clamps that compress an elastomer O-Ring held in a centering ring between two flange faces to create a high vacuum seal.

 

ISO KF flange sizes reference the inner diameter in millimeters of vacuum tubing. A KF flange size chart can be found below.

 

KF Flange Size Chart

ISO Size Tubing I.D. (mm) Flange Reference Tubing O.D. (in.)
NW10 10 QF10 0.50
NW16 16 QF16 0.75
NW25 25 QF25 1.00
NW40 40 QF40 1.50
NW50 50 QF50 2.00

 

ISO Flanges (ISO-LF Large Flange, ISO-LFB Large Flange, Bolted)

ISO flanges are used to form high vacuum connections in 2.5″ (LF63) to 20″ (LF500) diameter vacuum system tubing. ISO flanges are sexless, infinitely rotatable, and fastened with claw clamps or bolts to compress an elastomer O-Ring held in a centering ring between two flange faces to create a high vacuum seal. Two types of ISO flanges with different fastening styles exist. ISO LF flanges, also called ISO-K flanges, use claw clamps secured to an outer rim on the flanges to fasten. ISO LFB flanges, also called ISO-F flanges, use bolts to fasten through bolt holes in the flange.

 

ISO flange sizes reference the inner diameter in millimeters of vacuum tubing. An ISO flange size chart can be found below.

 

ISO Flange Size Chart

ISO Size Tubing I.D. (mm) Flange Size Tubing O.D. (in.)
NW63 63 LF63 2.50
NW80 80 LF80 3.00
NW100 100 LF100 4.00
NW160 160 LF160 6.00
NW200 200 LF200 8.00
NW250 250 LF250 10.00
NW320 320 LF320-1200 12.00
NW320 320 LF320-1275 12.75
NW400 400 LF400 16.00
NW500 500 LF500 20.00

 

KF and ISO Flange Types

Blank flanges are manufactured with no weld prep and no tubing bore. They are commonly used to close unused ports or they are altered by customers with their own machining capability for special use. ANCORP offers QF blank flanges, LF blank flanges, and LFB blank flanges.

 

Weld flanges are manufactured with a weld prep and tubing bore for immediate installation on your vacuum system with no additional alteration. We offer weld flanges in four different designs to meet your specific requirements:

 

 

QF Unbored stub flanges are manufactured with no weld prep and no tubing bore. They are commonly altered by customers with their own custom machining capability for special use.