When to use BELLOW SEAL valve

A metal bellows (typically welded from 316L SS) replaces the traditional packing gland, encapsulating the valve stem to achieve an all-metal seal and zero external leakage.

Semiconductor specialty gases include:

AsH₃ (Arsine), PH₃ (Phosphine), B₂H₆ (Diborane)

SiH₄ (Silane), GeH₄ (Germane)

Cl₂, HCl, HBr, NF₃

Any external leakage of these gases can cause personnel casualties or explosions. The bellows seal is the only solution that provides a dual containment barrier (Primary: Bellows + Secondary: Packing as backup) while ensuring all-metal flow path cleanliness.

The fatigue life of a bellows is significantly lower than that of a diaphragm valve. 10,000–50,000 cycles is the typical design life. For frequently actuated applications (e.g., ALD pulse valves), regular replacement or enhanced bellows designs are required.