Open and Closed Ended Rotor in Rotary Airlock Valve

The rotor can also classified based on the open and closed ended construction of rotor or rotor assembly. Majority of the manufacturers offer both types. In case of open end rotor construction / assembly, the pockets between the vanes is contained on both sides by the rotor assembly of the end plates of the housing of the rotary valve. This is the most common type of style of construction of the rotary valve. The bulk solids material passing through such rotor assembly comes in contact with the end plates and the bore of the valve housing. Due to the open end construction the bulk solids material when getting discharged through the rotary valve gets migrated towards the seals. There is no obstruction or any arrangement to contain this migration. Hence this causes wear of the seal. This is a major drawback of the open ended construction of the rotor assembly. The ability of the valve to contain the material leakage depends solely on the quality and type of seal.

Rotary Valve

Contrary to the open ended design, the closed ended design has two plates to seal the pockets from the side, this prevents the material from migrating to the seal when the material is getting discharged from the inlet to the outlet. In case the rotor assembly is fabricated the plates are welded to each end of the blades or vanes. While when the rotor is manufactured out of casting or molding, the plates are cast as part of the rotor. The end plates are also known as shrouds. The wear and tear in this case is greatly reduced.

In general closed ended rotor assembly has better performance capability compared to the open ended construction wherever wear and tear is a problem. It is also a better option in case of better sealing requirement for pressure difference.