pentair 3.25" Black Bulkhead Union Valve Nut

The Pentair 3.25" Black Bulkhead Union Valve Nut (Product #: 51013011 / 51013011Z) is a factory-original OEM replacement fastening hardware component designed to secure high-pressure plumbing connections on pool and spa filtration setups. Specifically engineered for use with Pentair, American Products, and PacFab push-pull (slide) backwash valves, this threaded union collar spins smoothly onto the filter tank's bulkhead fitting to compress the internal union adapter and o-ring. This mechanical configuration establishes an absolute, watertight seal that prevents pressure-side weeping and guards against suction-side air induction, which would otherwise cause pump cavitation and a loss of prime. Injection-molded from a premium, thick-walled engineering thermoplastic polymer, the nut features an oversized 3-1/4 inch diameter housing with heavily ribbed exterior gripping segments that allow pool service technicians or homeowners to achieve maximum torque during hand-tightening without stripping the threads. Infused with dense UV stabilizers, the component offers long-term resistance to brittleness, cracking, and structural fading caused by intense sun exposure, extreme pump pad heat, and aggressive sanitation chemistry like concentrated chlorine, bromine, or salt-chlorine generation. Built to safely withstand baseline hydraulic surges up to 50 PSI during high-velocity backwash cycles, this collar ensures the valve remains rigidly anchored to the main filter body. The physical dry weight of this single Pentair 3.25" Black Bulkhead Union Valve Nut is approximately 0.10 pounds (roughly 1.6 ounces, with a packaged shipping weight of approximately 0.15 pounds), providing an exceptionally durable, lightweight, and critical structural hardware replacement for efficient pool water circulation.