Confused about vacuum flange selection?
Understanding the vacuum flange types can help you choose the correct end connection. This is crucial for creating a vacuum system, because a tight seal is a prerequisite for achieving vacuum conditions.
As a pipe connection device, vacuum flange plays an important role in achieving efficient and safe connection.
Vacuum flange is specially used for vacuum line connection. It helps connect various vacuum chambers, vacuum pumps, etc., and is an important method to achieve vacuum connection. Compared with industrial positive pressure flanges, it has higher requirements on flange material and surface condition. Vacuum flange is made of high-quality stainless steel, and the standard material is stainless steel 304. The vacuum flange is processed by precision CNC and polished, and the surface roughness is very low. Excellent surface roughness is one of the key factors affecting vacuum sealing. Different types of vacuum flanges work with sealing materials to provide guarantees to meet different vacuum level needs.
Vacuum flanges use international standards that are recognized worldwide, giving them excellent versatility and the ability to connect to a variety of vacuum fittings.
This post will introduce the different types of vacuum flanges, their respective advantages and disadvantages. A deeper understanding of them will help you choose the most ideal flange for different vacuum applications.
KF flanges are small flanges for quick connection. KF clamps are used to quickly assemble or disassemble two KF flanges with identical structures. These components are small and simple in design and can be easily manipulated by hand without the help of any other tools. A matching O-ring is placed between the two KF flanges, which are wrapped and locked by the KF clamp. The V-groove on the inside of the KF clamp applies force to the two KF flanges at the same time and further squeezes the rubber O-ring, thereby achieving effective sealing.
Common vacuum flange types are KF/NW flange, ISO flange, CF flange.
KF/NW flange
Size
KF flange is a small size flange. Its full sizes are KF110, KF16, KF25, KF40, KF50.
Applications
KF flanges are suitable for low to medium vacuum applications.
Advantages
- Most widely used
- Easy to assemble or disassemble
- Low cost
Disadvantages
- Few sizes
- 0-180 degrees Celsius available
- Low to medium vacuum applications
ISO flange
ISO flanges are larger and serve as an effective complement to KF flanges. The sealing principle of ISO flanges is the same as that of KF flanges, where a seal is formed by the compression of a rubber O-ring between the sealing surfaces of two mating flanges. ISO flanges have two different fastening methods. ISO-K flanges use multiple double-claw clamps to lock two mating flanges together from the circular groove on the back of the flanges. ISO-F flanges use traditional bolt connections.
Types
ISO-K
ISO-F
Sizes
From ISO63 to ISO500
Applications
From medium vacuum to high vacuum
Advantages
- Robust and reliable
- Wide size range
Disadvantages
- More complex installation
- Increased cost
CF flange
CF flanges are fully metal-to-metal seals suitable for ultra-high vacuum (UHV) applications. CF flanges have a unique knife edge design that is slightly lower than the flange sealing surface. A copper gasket is placed between two identical CF flanges. When the bolts are tightened, the hard stainless steel knife edges squeeze the relatively soft copper gasket, filling the gap around the knife edges to form a seal. Thanks to the metal seal, CF flanges can withstand higher bake-out temperatures.
Sizes
From CF16to CF250
Applications
Ultra-high vacuum (UHV) applications
Advantages
- Ultra-high vacuum compatible
- Bakeable
Disadvantages
- Complex installation
- High cost
- Gaskets are not reusable
Custom Flange
With decades of industry experience and resource accumulation, KIPFLEX can provide customers with a variety of custom flanges.
Factors to Consider When Choosing a Vacuum Flange
Vacuum Level Required
Understand the vacuum level of the application and choose the matching flange type based on it.
Application and Environment
Consider materials. Use materials suited for the application. Stainless steel and aluminum are typical choices.
Size and Compatibility
Combine vacuum level and size range to find the ideal flange.
Temperature Requirements
The application temperature of KF and ISO flanges is limited by the O-ring material. CF flanges are more suitable for high temperature baking.
Cost and Availability
Cost is an important factor affecting purchase. Size, material, and flange type must be considered. For low vacuum applications, KF is obviously the most economical option.
If you have any more questions, just ask the KIPFLEX engineering team for help.
