A corrugated thin-wall tube, hydroformed or edge-welded from stacked diaphragms, that stretches, compresses and bends while holding vacuum. Bellows isolate pump vibration, take up misalignment between flanges, and seal the stems of valves and linear motion feedthroughs. Their thin walls make them prone to fatigue cracks and pinholes, so a valve that starts leaking after many cycles often has a cracked bellows.
Gate valve bellows cracked after half a million cycles, the leak only shows when the valve's open.
Also heard as
- flex hose
- flex line
- bellows hose
Related terms
Feedthrough
Sealed fitting that carries electricity, motion, fluid or light through a vacuum wall without leaking.
Gate valve
Full-bore valve with a sliding plate that isolates a high vacuum pump or a load lock from the chamber.
Chase a leak
To hunt down a leak of unknown location joint by joint, often over hours, until the source is pinned down.