API-610 VS1 PUMP (SUMP TYPE)
The API-610 VS1 Vertical Turbine Pump a is Vertical turbine design (also known as wet pit, diffuser) with diffuser vanes in the pump bowl. Flow follows the axis of the pump shaft. See Figure below. The API 610 designation for this type of pump is VS1. This pump is used if there is insufficient NPSHA for a horizontal pump. Therefore, the VS1 pumps are supported above the medium to be pumped. The vertically oriented impellers are suspended below the support and are submerged into the medium. VS (Vertically Suspended) Pumps can be single or multistage and in theory can work to a limitless depth. VS1 pumps achieve this through the ability to have multiple stages stacked one on top of the other (see Figure 2). They can achieve a lower Net Positive Suction Head (NPSH) by designing for this specifically in the first stage and then follow it up with unique high head per stage series hydraulics in subsequent stages.
The fluid is pumped from the sump through the support column and out into a discharge bend. The sharp bend on the discharge however produces a loss in performance. The VS1 pump generally requires a double mechanical seal and Plan 53 seal support system to prevent leakage.
The bearings of the shaft in each stage of a VS1 pump are mounted inside the support column by spiders. This works well for relatively clean fluids but where the fluid being pumped contains sand or grit wear of the spiders can occur. In addition, where sand or grit is present, VS1 pumps require a seal support system to enable a clean flush to be fed to the bearings.
API 610 11th edition multistage vertical turbine VS6
( can barrel) and VS1 (open sump) pumps