Pentair - UltraFlow Plus prefilter lid - R39301799

Pentair UltraFlow Plus prefilter lid

This is the OEM prefilter strainer pot lid (part #17 on the Pentair UltraFlow Plus exploded diagram) that seals the strainer housing on the suction side of the pump. It closes the pre-filter chamber where the debris basket sits, maintaining prime and keeping the hydraulic circuit under pressure. Without a sound, crack-free lid, the pump loses suction and cavitates.

What this prefilter lid does in the UltraFlow Plus

The lid threads onto the strainer pot via a quarter-turn bayonet system, creating a watertight seal over the debris basket. You lift it to inspect and empty the basket without tools — the transparent body lets you assess debris level at a glance before opening. A dedicated lid gasket (R39300600, sold separately) seats into the underside groove and is the first thing to check if the seal weeps.

Which UltraFlow Plus models it fits

This lid fits the full UltraFlow Plus single-phase and three-phase range: models P-UFL-071, P-UFL-073, P-UFL-101, P-UFL-103, P-UFL-151, P-UFL-153, P-UFL-201, P-UFL-203, P-UFL-301, and P-UFL-303. It also fits the Intelliflo UltraFlow VSD (model UFL-VSD) and the Ultra-Glas S5P3R series. Verify your pump model label before ordering — the lid is not interchangeable with non-UltraFlow Pentair strainer pots.

Sinais de que precisa de ser substituído

UV exposure and pool chemicals degrade the polycarbonate over time, causing hazing, stress cracks, or a warped seating flange. If the pump loses prime repeatedly despite a new gasket, or if you see visible crazing around the bayonet lugs, the lid itself is the fault. A cracked lid draws air into the volute, starving the impeller and triggering thermal cutout on the motor.

Como instalá-lo

Switch off and isolate the pump, then turn the old lid a quarter-turn anti-clockwise to release it from the bayonet retaining ring (R39105000). Lift out the debris basket, seat the lid gasket into the groove on the new lid, align the lugs with the pot collar, and press down while rotating a quarter-turn clockwise until it clicks. Re-prime and check for weeping at the seal before returning the pump to service — takes under five minutes with no tools required.