Little Split Flow Design Configuration Options
There are two different design configurations for incorporating the Little Split
Flow feature into horizontal or vertical inline API Standard 610 overhung
- The auxiliary impeller hub is back-to-back with the primary impeller
hub, reference prototype BW/IP sectional drawing.
- The auxiliary impeller has the same orientation on the shaft as
the primary impeller, reference CPC sectional drawing.
To facilitate comparison, liquid flowing through the pumps is color-coded, i.e.
- Inlet liquid - green
- Primary discharge - red
- Secondary discharge (from auxiliary impeller) - blue
The Flowserve and Sulzer designs use external feed lines from the
primary impeller discharge to the auxiliary impeller inlet. They also
use back (hub) wear rings on the primary impeller. This
configuration has running clearances at four locations. The auxiliary
impeller hub ring clearance breaks down approximately 100% of the total
differential head (TDH); the other three running clearances each
break down approximately 50% of the TDH.
- The CPC design provides for internal feed from the primary
impeller discharge to the auxiliary impeller inlet by deleting back
(hub) wear rings from the primary impeller, and unbalancing the
auxiliary impeller to offset the primary impeller axial dynamic
unbalance. This configuration has running clearances at three
locations. Each running clearance breaks down approx. 50% of the
TDH. This configuration also minimizes the shaft cantilever, which in turn, results
in lower dynamic rotor deflections at the running clearances.
- Both designs provide axial hydraulic balance of the rotors and shaft
seals operate at the primary impeller discharge head.
Stay tuned for drawings:
Note: This site is under construction.
- Prototype BW/IP sectional drawing
- CPC sectional drawing