Pentair - UltraFlow Plus impeller wear ring - R39006900

Pentair UltraFlow Plus impeller wear ring

This is the OEM impeller wear ring (part R39006900) for the Pentair UltraFlow Plus pool pump family. It sits between the rotating impeller and the pump volute, forming a controlled annular clearance that keeps high-pressure discharge water from leaking back to the suction side and robbing the pump of hydraulic efficiency.

What this wear ring does in the UltraFlow Plus

The wear ring provides a restrictive annulus between the high-pressure discharge zone and the low-pressure suction eye of the impeller. When the clearance is correct, the pump delivers its rated flow and head. As the ring erodes, high-pressure water recirculates back through the gap to the suction inlet, flow output drops, and the motor draws more current for less result. Replacing the ring restores the designed hydraulic seal without touching the impeller or volute themselves.

Which UltraFlow Plus models it fits

This wear ring is listed against the Pentair UltraFlow Plus pump family. The part number R39006900 traces directly to the American Products Ultra-Flow lineage that Pentair absorbed, and it appears across the UltraFlow range. Confirm your specific pump model against the parts diagram before ordering — the ring is not universal across all Pentair pump ranges.

Signs it needs replacing

Watch for a sustained drop in filter pressure to roughly half the normal operating reading, reduced return-jet velocity at the pool inlets, or a low grinding cavitation noise from the pump housing. If the pump basket fills slowly or water swirls rather than drawing in briskly, a worn ring allowing internal recirculation is a primary suspect alongside a clogged impeller. Inspect the ring whenever you have the pump wet end apart — wear is not always visible until you check the clearance.

How to install it

Isolate and lock off the pump electrically before opening the wet end. Remove the clamp ring, separate the volute from the seal plate, and withdraw the impeller. The wear ring locates in the volute mouth around the impeller eye — press the old ring out, seat the new one flush, and reassemble in reverse order. The task takes around 20–30 minutes with basic hand tools and does not require a pump seal replacement unless the mechanical seal is also due.

Why genuine Pentair matters

The wear ring clearance is a precision fit: an undersized aftermarket ring risks contact with the spinning impeller, while an oversized one defeats the hydraulic seal it is there to maintain. Genuine Pentair parts are dimensioned to the original engineering tolerances, ensuring the correct running gap is restored and pump efficiency returns to specification.