Pump Impeller

Multi-Stage Pump Impeller

The impeller is the portion of a centrifugal pump that does the work.  Water enters the impeller and is accelerated across the vanes.  There are three different types of pump impellers: open, semi-open, or enclosed.

Impellers can be either single suction or double-suction.  A single-suction impeller allows liquid to enter from only one direction.  A double-suction impeller allows liquid to enter from both sides simultaneously.

An impeller is commonly abbreviated as IMPLR.

Open Impeller

The fluid enters the eye of the impeller where the turning vanes add energy to the fluid and direct it to the discharge nozzle.  A close clearance between the vanes and the pump backing plate, prevents most of the fluid from recirculating back to the eye of the impeller.

Closed Impeller

Also known as an enclosed impeller or a shrouded impeller.  The fluid enters the eye of the impeller where the vanes add energy to the fluid and direct it to the discharge nozzle.  There is no impeller to volute or back plate clearance to set.  Wear rings restrict the amount of discharge fluid that recirculates back to the suction side of the impeller.  When this wear ring clearance becomes excessive the wear rings must be replaced.