How to choose flexible vacuum bellow?

The core difference lies in whether it possesses the capability of "axial compression." Simply put, rigid bellows primarily address the issue of "misalignment," while flexible bellows can also resolve problems of "length variation" and "vibration.".

To help you distinguish accurately, the roles of these two types in the vacuum system are as follows:

• Flexible (compressible) bellows: Similar to an accordion bellows. In addition to bending, its core advantage is the ability to be compressed or stretched axially. It is specifically designed to absorb thermal expansion and contraction of pipelines, compensate for installation dimensional errors, and isolate pump group vibrations. The service life typically exceeds 10,000 cycles.
• Rigid (non-compressible) corrugated hose: Can be freely bent for routing, but the length is essentially fixed and cannot be axially compressed. It primarily addresses directional deviations or spatial routing issues in static connections. Once both ends are secured, the length remains unchangeable.

Additionally, there are two other points to note based on the molding process and vacuum level:

• Forming method: Hydraulic forming (with weld seams) is commonly used for general vacuum applications, offering good cost-effectiveness; welded corrugated diaphragms (without weld seams) are employed for ultra-high vacuum (with a limit of 1.3E-11 Pa), providing superior performance but at a higher cost.

Interface type: KF quick-release flange (convenient) suitable for coarse/low vacuum; CF flange (bolted) suitable for ultra-high vacuum and capable of withstanding temperatures up to around 450°C.