The difference between three common vacuum flange specifications (CF, KF, ISO)
1. CF flange
Conflat Flange is a flange connection used in ultra-high vacuum, a metal static seal that can withstand high temperature baking.
Nominal diameter sizes include: DN16, 40, 63, 100, 160, 200, 250
The applicable vacuum degree is as high as 10-12 mbar (do not know how much Pa is equal to mbar? Then quickly use the vacuum unit online conversion tool:
Flange sealing materials are usually vacuum pipeline accessories such as Viton, PTFE, oxygen-free copper, etc.
Flanges are usually 304, 316 stainless steel, etc.:
CF flanges are suitable for vacuum standards:
GB/T 6070-2007 Vacuum technology Flange size
GB/T 6071-2003 Ultra-high vacuum flange
2. ISO-KF
ISO-KF is a quick release flange used in vacuum systems. It consists of the following components: two symmetrically distributed KF flanges, O-Rings, centering brackets, and clamps. No additional tools are required to loosen or compress the coupling by simply turning the disc nut by hand.
ISO-KF vacuum fittings are small size quick flange fittings. Nominal diameter sizes include: DN 10, 16, 25, 40, 50.
Manufacturing standards include: DIN 28403, ISO 2861
Suitable for vacuum levels up to 10-8 mbar.
Flange sealing materials are usually Viton, Buna, Silicone, EPDM, aluminum, etc.
Flanges are usually 304, 316 stainless steel, etc.
ISO-KF vacuum fittings usually consist of flange, clamp, O-Ring and centering ring.
ISO-KF applicable vacuum standards:
GB/T 4982-2003 Vacuum technology – Quick release connectors – Dimensions – Part 1: Clamping type
GB/T 4983-2003 Vacuum technology – Quick release connectors – Dimensions – Part 2: Screw-on type
3. ISO flange
ISO flanges and piping can be used in a variety of applications, from atmospheric pressure to high vacuum, that are often assembled and disassembled. Typically the diameter of the pipe exceeds 50mm (2 inches). Can withstand 150°C bake if Viton O-rings are used.
The two commonly used forms of ISO flanges are ISO-K and ISO-F
ISO-K and ISO-F vacuum fittings are large size vacuum fittings in nominal diameters: DN 63, 100, 160, 200, 250, 320, 400, 500 and 630
Manufacturing standards include: DIN 28404, ISO 1609
Can be used where vacuum levels up to 10-8 mbar are required.
Flange sealing materials are usually Viton, Buna, Silicone, EPDM, aluminum wire, etc.
Flanges are usually 304, 316 stainless steel, etc.
a. ISO-K vacuum joint is usually composed of flange, flange claw, sealing ring (O-Ring) and centering ring.
b. ISO-F vacuum joint is usually composed of flange (flang), sealing ring (O-Ring) and centering ring (centering ring). The difference from ISO-K is that the flange is firm with bolts.
ISO flange applicable vacuum standard:
JB/T 1090-1991 Type and size of J-type vacuum rubber sealing ring
JB/T 109l-1991 JO type and skeleton type vacuum rubber sealing ring type and size
JB/T 1092-1991 Type and size of rubber sealing ring for O-type vacuum