# What is a KF Series Vacuum Flange? **URL:** \ **Category:** OFSCN Technical Knowledge Base\ **Tags:** fbg-technology\ **Created:** [June 15, 2026, 2:31pm UTC](https://forum.ofscn.net/t/kf-what-is-a-kf-klein-flange-vacuum-interface/1945 "2026-06-15T14:31:29Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\ **Post date:** [June 15, 2026, 2:31pm UTC](https://forum.ofscn.net/t/kf-what-is-a-kf-klein-flange-vacuum-interface/1945/1 "2026-06-15T14:31:29Z")
How are these quick-release clamp connectors used in laboratory vacuum equipment? ---
**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\ **Post date:** [June 15, 2026, 2:32pm UTC](https://forum.ofscn.net/t/kf-what-is-a-kf-klein-flange-vacuum-interface/1945/2 "2026-06-15T14:32:00Z")
In laboratory vacuum equipment, the **KF (Klein Flange, also known as Quick Flange)** series vacuum fittings with quick clamps are widely used for system connections ranging from low vacuum (rough vacuum) to high vacuum (around 1 \times 10^{-5}\ \text{Pa}) due to their excellent sealing performance and extremely high assembly/disassembly efficiency. Here is a detailed analysis of their specific applications and engineering physics principles: ### I. Design and Sealing Principle of KF Series Vacuum Fittings The design of KF fittings is highly standardized (common specifications include KF10, KF16, KF25, KF40, KF50, etc.) and relies on the coordinated work of the following four core components to achieve vacuum sealing: 1. **Symmetrical Flange** : The contact surfaces of the two flanges are flat, with a 15^{\circ} bevel on the outer edge. 2. **Centering Ring** : Used to align the two flanges and prevent horizontal misalignment. 3. **Elastic O-ring** : Typically made of vacuum-compatible, low-outgassing elastomers such as Viton, fitted over the outside of the centering ring. 4. **Quick Clamp** : The inner side of the clamp has a beveled groove that mates with the flange edge, secured by tightening a wing nut by hand. When the clamp is tightened, the inner bevel of the clamp generates an axial component of force on the 15^{\circ} bevel of the flange, squeezing the two flanges towards each other. This causes the O-ring to elastically deform and press tightly against the sealing end face of the flange, thereby blocking the interface with the atmosphere and achieving an airtight connection. * * * ### II. Typical Application Scenarios in Laboratory Vacuum Equipment In physics, chemistry, materials, and optics laboratories, KF fittings with quick clamps are commonly used in the following areas: 1. **Vacuum System Reconfiguration and Frequent Assembly/Disassembly** In vacuum tube furnaces, Chemical Vapor Deposition (CVD)/Physical Vapor Deposition (PVD) systems, mass spectrometers, turbomolecular pump units, or glovebox transfer chambers, experiments often require frequent sample changes, cleaning of reaction residues, or reconfiguration of pipelines. KF fittings require no wrenches or tools; they can be assembled or disassembled in seconds simply by hand-tightening the quick clamp, significantly reducing the labor time for experimental system adjustments. 2. **Gas Inlet and Vacuum Pump Unit Cascading** Used to connect a foreline mechanical pump (rotary vane pump, dry pump) to the main vacuum chamber or the inlet of a turbomolecular pump. Since mechanical pumps produce slight vibrations during operation, the combination of the elastic O-ring and a metal bellows can also provide a certain degree of vibration isolation. 3. **In-situ Signal Introduction (Fiber Optic Vacuum Feedthrough/Pass-through)** When performing in-situ optical measurements on samples in a vacuum environment (such as fiber Bragg grating sensing, vacuum spectral monitoring, laser delivery, etc.), it is necessary to introduce optical fiber leads through the vacuum wall. In such cases, KF quick-connect vacuum sealed flanges integrated with fiber optic channels allow for non-destructive signal introduction while maintaining the high vacuum inside the chamber. * * * ### III. OFSCN® Official Products: Fiber Optic Vacuum Sealed Flanges and Technical Specifications To meet the demand for introducing optical or sensor signals into laboratory vacuum systems, Beijing Dacheng Yongsheng Technology Co., Ltd. offers specialized [OFSCN® Fiber Optic Vacuum Sealed Flanges](https://www.ofscn.org/connectors/fiber-optic-sealed-flange.html). These products enable non-destructive fiber optic introduction into vacuum environments and boast extremely high airtightness specifications: - **Core Parameter Specifications** : - **Flange Specifications** : Divided into **KF Series** (quick clamp type, suitable for medium-high vacuum and rapid maintenance) and **CF Series** (knife-edge metal seal type, suitable for ultra-high vacuum and bake-out). - **Structural Form** : Supports customized male, female, single-head, or multi-head fiber optic pass-through configurations. - **Vacuum Seal Rating** : Ultimate vacuum better than 1 \times 10^{-5}\ \text{Pa} to 1 \times 10^{-7}\ \text{Pa}. - **Temperature Adaptability** : For use at room temperature, with options for products resistant to high temperatures up to 250\ ^{\circ}\text{C}. - **More Connectors and Branching Products** : Refer to the [Official Category Link](https://www.ofscn.org/connectors.html). #### Standard Product Display ![OFSCN® CF35 Vacuum Sealed Flange](https://forum.ofscn.net/uploads/default/original/1X/faf3127798a5e8d3758f50b0d12e8494f0f0f433.jpeg) ![OFSCN® KF25 Vacuum Sealed Flange Patch Cord](https://forum.ofscn.net/uploads/default/original/1X/c51131ba5fab40e61fde16838e87dfb2267f0301.jpeg)