The Difference Between Three Common Vacuum Flanges

The Difference Between Three Common Vacuum Flanges

Vacuum flanges are mostly used in vacuum equipment. The three common vacuum flanges are:

• CF flange
  

• KF flange

• ISO flange

What are the differences and connections between them? Here we will list the structures of the three flanges and the applicable standards one by one, hoping to help you.

（一）CF flange

CF flange is a flange connection used in ultra-high vacuum. It is a metal static seal that can withstand high temperature baking.

Applicable vacuum up to 10-12 mbar.

Flange sealing materials: Viton, PTFE

Flange Material: SS304, SS316

（二）ISO-KF flange

ISO-KF is a quick release flange used in vacuum systems. It consists of the following components: two KF flanges, O-Ring, centering ring, and KF swing clamp. The connection can be loosened or tightened by simply turning the wing nut by hand without the use of other tools.

Application: High vacuum

Vacuum range: 1x10-8 mbar

Material: SS304, SS316L

Gasket materials: Viton, Buna, Silicone, EPDM, etc.

（三）CF flange

ISO flanges are available from atmospheric pressure to high vacuum.

The two common forms of ISO flanges are ISO-K and ISO-F.

Application: High vacuum

Vacuum range: 1x10-9 mbar

Material: SS304, SS316L

Gasket materials: Viton, Buna, Silicone, EPDM, etc.

Flange sizes: ISO63-ISO630

Tube sizes: 12,7 mm - 152,4 mm

Temperature Range: < -200°C(150°C sustained)

1) ISO-K vacuum fitting clamp sets usually consist of flanges, ISO claw clamps, O-Ring, and centering ring.

2) ISO-F vacuum fitting clamp sets are usually composed of flanges, O-Ring, and centering ring. 

The difference from ISO-K is that the flanges are firmly bolted.

The bolt type flanges are assembled by using a set of bolts to fix the position of the flanges.

The claw clamp flanges use double claw clamps to hold two flanges together.