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The difference between three common vacuum flange specifications (CF, KF, ISO)

Time:2022-03-22
  Recently, I have often encountered people asking about the structure of vacuum flanges, such as what is a CF flange? What is a KF flange? What is an ISO flange? The ISO flange is divided into ISO-K and ISO-F. So what are the differences and connections between them? Indeed, these flanges are commonly used flange standards in the design and configuration of vacuum systems, and non-professionals are indeed easy to confuse. Therefore, Kejia Electric Furnace will list the three types of flange structures and applicable standards one by one. Come out, I hope it helps everyone.

1. CF flange
The English name of CF flange is Conflat Flang. It is a flange connection used in ultra-high vacuum, a metal static seal that can withstand high temperature baking.
The nominal diameter size includes: DN16, 40, 63, 100, 160, 200, 250.
The applicable vacuum is up to 10-12 mbar (10-14Pa).
Flange sealing materials are usually Viton, PTFE, oxygen-free copper, etc.
The flange is usually 304, 316 stainless steel, etc., as shown in the following figure:
 
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 kind of quick release flange used in vacuum system. 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 joint is a small size quick-install flange joint. Nominal diameter sizes include: DN 10, 16, 25, 40, 50.
Manufacturing standards include: DIN 28403, ISO 2861.
The applicable vacuum is up to 10-8 mbar (10-10Pa).
Flange sealing materials are usually Viton, Buna, Silicone, EPDM, aluminum, etc.
Flanges are usually 304, 316 stainless steel, etc.
ISO-KF vacuum joint is usually composed of flange, clamp, O-Ring, centering ring, as shown in the figure below.
 
ISO-KF applicable vacuum standards:
GB/T 4982-2003 Vacuum Technology Quick Release Connector Dimensions Part 1: Clamping Type
GB/T 4983-2003 Vacuum Technology Quick Release Connector Dimensions Part 2: Tightening 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
It can be used in applications requiring vacuum up to 10-8 mbar.
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, as shown in the figure below.
 
b. ISO-F vacuum joint is usually composed of flange (flang), sealing ring (O-Ring), centering ring (centering ring), and the difference from ISO-K is that the flange is firm with bolts. See below.
 
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

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